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1
Baker, Jason D., Charles W. Fowler, and George A. Antonelis. "Mass change in fasting immature male northern fur seals." Canadian Journal of Zoology 72, no. 2 (February 1, 1994): 326–29. http://dx.doi.org/10.1139/z94-045.
Повний текст джерелаАнотація:
Immature male northern fur seals (Callorhinus ursinus) lost an estimated 20–30% of their body mass while fasting during the breeding season on St. Paul Island, Alaska. This is somewhat less than the mass loss reported for territorial adult male pinnipeds. During fasting, absolute rates of mass change (averaging −0.68 kg∙day−1) were positively correlated with initial mass. Mass-specific rate of change (averaging 2%∙day−1) did not vary with age or initial mass. Although they lose large amounts of mass while fasting, immature male fur seals achieve a net increase in mass during the breeding season by making feeding trips to sea. We postulate that the capability for prolonged fasting in immature males facilitates the development of social and sexual skills that are likely to increase future reproductive success.
2
Bani, Borruso, Matthews Nicholass, Bardelli, Polo, Pioli, Gómez-Brandón, Insam, Dumbrell, and Brusetti. "Site-Specific Microbial Decomposer Communities Do Not Imply Faster Decomposition: Results from a Litter Transplantation Experiment." Microorganisms 7, no. 9 (September 12, 2019): 349. http://dx.doi.org/10.3390/microorganisms7090349.
Повний текст джерелаАнотація:
Microbes drive leaf litter decomposition, and their communities are adapted to the local vegetation providing that litter. However, whether these local microbial communities confer a significant home-field advantage in litter decomposition remains unclear, with contrasting results being published. Here, we focus on a litter transplantation experiment from oak forests (home site) to two away sites without oak in South Tyrol (Italy). We aimed to produce an in-depth analysis of the fungal and bacterial decomposer communities using Illumina sequencing and qPCR, to understand whether local adaptation occurs and whether this was associated with litter mass loss dynamics. Temporal shifts in the decomposer community occurred, reflecting changes in litter chemistry over time. Fungal community composition was site dependent, while bacterial composition did not differ across sites. Total litter mass loss and rates of litter decomposition did not change across sites. Litter quality influenced the microbial community through the availability of different carbon sources. Additively, our results do not support the hypothesis that locally adapted microbial decomposers lead to a greater or faster mass loss. It is likely that high functional redundancy within decomposer communities regulated the decomposition, and thus greater future research attention should be given to trophic guilds rather than taxonomic composition.
3
Farías-Barahona, David, Álvaro Ayala, Claudio Bravo, Sebastián Vivero, Thorsten Seehaus, Saurabh Vijay, Marius Schaefer, Franco Buglio, Gino Casassa, and Matthias H. Braun. "60 Years of Glacier Elevation and Mass Changes in the Maipo River Basin, Central Andes of Chile." Remote Sensing 12, no. 10 (May 21, 2020): 1658. http://dx.doi.org/10.3390/rs12101658.
Повний текст джерелаАнотація:
Glaciers in the central Andes of Chile are fundamental freshwater sources for ecosystems and communities. Overall, glaciers in this region have shown continuous recession and down-wasting, but long-term glacier mass balance studies providing precise estimates of these changes are scarce. Here, we present the first long-term (1955–2013/2015), region-specific glacier elevation and mass change estimates for the Maipo River Basin, from which the densely populated metropolitan region of Chile obtains most of its freshwater supply. We calculated glacier elevation and mass changes using historical topographic maps, Shuttle Radar Topography Mission (SRTM), TerraSAR-X add-on for Digital Elevation Measurements (TanDEM-X), and airborne Light Detection and Ranging (LiDAR) digital elevation models. The results indicated a mean regional glacier mass balance of −0.12 ± 0.06 m w.e.a−1, with a total mass loss of 2.43 ± 0.26 Gt for the Maipo River Basin between 1955–2013. The most negative glacier mass balance was the Olivares sub-basin, with a mean value of −0.29 ± 0.07 m w.e.a−1. We observed spatially heterogeneous glacier elevation and mass changes between 1955 and 2000, and more negative values between 2000 and 2013, with an acceleration in ice thinning rates starting in 2010, which coincides with the severe drought. Our results provide key information to improve glaciological and hydrological projections in a region where water resources are under pressure.
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Vanbeveren, Dany. "Close pairs: keys to comprehension of star cluster evolution." Proceedings of the International Astronomical Union 5, S266 (August 2009): 293–303. http://dx.doi.org/10.1017/s1743921309991165.
Повний текст джерелаАнотація:
AbstractIn this review I first summarize why binaries are key objects in the study of stellar populations, to understand the evolution of star clusters and galaxies, and thus to understand the universe. I then focus on four specific topics: (i)the formation (through binaries) and evolution of very massive stars in dense clusters and the importance of stellar-wind mass loss. I discuss preliminary computations of wind mass-loss rates of very massive stars performed with the Munich hydrodynamical code and the influence of these new rates on the possible formation of an intermediate-mass black hole in the cluster MGG 11 in M82;(ii)the evolution of intermediate-mass binaries in a starburst with special emphasis on the variation of the supernova (SN) Ia rate (i.e., on the delayed time distribution of SNe Ia). A comparison with SN Ia rates in elliptical galaxies may provide important clues to SN Ia models as well as to the evolution of SN Ia progenitors;(iii)the evolution of double-neutron-star mergers in a starburst (i.e., the delayed time distribution of these mergers) and what this tells us about the suggestion that these mergers may be important production sites of r-process elements;(iv)the possible effect of massive binaries on the self-enrichment of globular clusters.
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Stone, G. N. "ENDOTHERMY IN THE SOLITARY BEE ANTHOPHORA PLUMIPES: INDEPENDENT MEASURES OF THERMOREGULATORY ABILITY, COSTS OF WARM-UP AND THE ROLE OF BODY SIZE." Journal of Experimental Biology 174, no. 1 (January 1, 1993): 299–320. http://dx.doi.org/10.1242/jeb.174.1.299.
Повний текст джерелаАнотація:
1. This study examines variation in thoracic temperatures, rates of pre-flight warm-up and heat loss in the solitary bee Anthophora plumipes (Hymenoptera; Anthophoridae). 2. Thoracic temperatures were measured both during free flight in the field and during tethered flight in the laboratory, over a range of ambient temperatures. These two techniques give independent measures of thermoregulatory ability. In terms of the gradient of thoracic temperature on ambient temperature, thermoregulation by A. plumipes is more effective before flight than during flight. 3. Warm-up rates and body temperatures correlate positively with body mass, while mass-specific rates of heat loss correlate negatively with body mass. Larger bees are significantly more likely to achieve flight temperatures at low ambient temperatures. 4. Simultaneous measurement of thoracic and abdominal temperatures shows that A. plumipes is capable of regulating heat flow between thorax and abdomen. Accelerated thoracic cooling is only demonstrated at high ambient temperatures. 5. Anthophora plumipes is able to fly at low ambient temperatures by tolerating thoracic temperatures as low as 25 sC, reducing the metabolic expense of endothermic activity. 6. Rates of heat generation and loss are used to calculate the thermal power generated by A. plumipes and the total energetic cost of warm-up under different thermal conditions. The power generated increases with thoracic temperature excess and ambient temperature. The total cost of warm-up correlates negatively with ambient temperature.
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Uttenthaler, S., I. McDonald, K. Bernhard, S. Cristallo, and D. Gobrecht. "Interplay between pulsation, mass loss, and third dredge-up: More about Miras with and without technetium." Astronomy & Astrophysics 622 (February 2019): A120. http://dx.doi.org/10.1051/0004-6361/201833794.
Повний текст джерелаАнотація:
Context. We follow-up on a previous finding that AGB Mira variables containing the third dredge-up indicator technetium (Tc) in their atmosphere form a different sequence of K − [22] colour as a function of pulsation period than Miras without Tc. A near- to mid-infrared colour such as K − [22] is a good probe for the dust mass-loss rate of the stars. Contrary to what might be expected, Tc-poor Miras show redder K − [22] colours (i.e. higher dust mass-loss rates) than Tc-rich Miras at a given period. Aims. Here, the previous sample is extended and the analysis is expanded towards other colours and dust spectra. The most important aim is to investigate if the same two sequences can be revealed in the gas mass-loss rate. Methods. We analysed new optical spectra and expanded the sample by including more stars from the literature. Near- and mid-IR photometry and ISO dust spectra of our stars were investigated where available. Literature data of gas mass-loss rates of Miras and semi-regular variables were collected and analysed. Results. Our results show that Tc-poor Miras are redder than Tc-rich Miras in a broad range of the mid-IR, suggesting that the previous finding based on the K − [22] colour is not due to a specific dust feature in the 22 μm band. We establish a linear relation between K − [22] and the gas mass-loss rate. We also find that the 13 μm feature disappears above K − [22]≃2.17 mag, corresponding to Ṁg ∼ 2.6 × 10−7 M⊙ yr−1. No similar sequences of Tc-poor and Tc-rich Miras in the gas mass-loss rate vs. period diagram are found, most probably owing to limitations in the available data. Conclusions. Different hypotheses to explain the observation of two sequences in the P vs. K − [22] diagram are discussed and tested, but so far, none of them convincingly explains the observations. Nevertheless, we might have found an hitherto unknown but potentially important process influencing mass loss on the TP-AGB.
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Houlihan, D. F., K. Kelly, and P. R. Boyle. "Correlates of Growth and Feeding in Laboratory-Maintained Eledone Cirrhosa (Cephalopoda: Octopoda)." Journal of the Marine Biological Association of the United Kingdom 78, no. 3 (August 1998): 919–32. http://dx.doi.org/10.1017/s0025315400044878.
Повний текст джерелаАнотація:
Octopuses (Eledone cirrhosa (Octopoda: Cephalopoda)) held in an aquarium were subjected to varying conditions of feeding and starvation to evaluate putative indices of feeding and growth. Specific growth rate (%d−1) was linearly related to feeding rate (% of the body mass d−1) in animals with a mean body mass of 250 g at 15°C. Maximum growth rates varied between > 2% d−1 (body weights < 300 g) to < 1% d−1 (body weights ≤ 900 g) but specific growth rates were not related to body weight. Growth rates became negative (weight loss) after one week without food.The digestive gland index (DGI) was significantly correlated with short and long-term feeding and specific growth rates, and with body weight. Muscle RNA concentration was linearly correlated with growth rate during the previous 1–3 weeks but not with feeding rate. RNA:protein ratios were not different between mid-arm and mantle sample sites but arm tip values were significantly higher. RNA:protein ratio was related to body weight only in feeding animals. It is concluded that DGI is an index of feeding rate and that RNA:protein ratio can be used as an index of recent (~ 4 weeks) growth rate.
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Ramdani, Ghania, Nadine Schall, Hema Kalyanaraman, Nisreen Wahwah, Sahar Moheize, Jenna J. Lee, Robert L. Sah, Alexander Pfeifer, Darren E. Casteel, and Renate B. Pilz. "cGMP-dependent protein kinase-2 regulates bone mass and prevents diabetic bone loss." Journal of Endocrinology 238, no. 3 (September 2018): 203–19. http://dx.doi.org/10.1530/joe-18-0286.
Повний текст джерелаАнотація:
NO/cGMP signaling is important for bone remodeling in response to mechanical and hormonal stimuli, but the downstream mediator(s) regulating skeletal homeostasis are incompletely defined. We generated transgenic mice expressing a partly-activated, mutant cGMP-dependent protein kinase type 2 (PKG2R242Q) under control of the osteoblast-specific Col1a1 promoter to characterize the role of PKG2 in post-natal bone formation. Primary osteoblasts from these mice showed a two- to three-fold increase in basal and total PKG2 activity; they proliferated faster and were resistant to apoptosis compared to cells from WT mice. Male Col1a1-Prkg2 R242Q transgenic mice had increased osteoblast numbers, bone formation rates and Wnt/β-catenin-related gene expression in bone and a higher trabecular bone mass compared to their WT littermates. Streptozotocin-induced type 1 diabetes suppressed bone formation and caused rapid bone loss in WT mice, but male transgenic mice were protected from these effects. Surprisingly, we found no significant difference in bone micro-architecture or Wnt/β-catenin-related gene expression between female WT and transgenic mice; female mice of both genotypes showed higher systemic and osteoblastic NO/cGMP generation compared to their male counterparts, and a higher level of endogenous PKG2 activity may be responsible for masking effects of the PKG2R242Q transgene in females. Our data support sexual dimorphism in Wnt/β-catenin signaling and PKG2 regulation of this crucial pathway in bone homeostasis. This work establishes PKG2 as a key regulator of osteoblast proliferation and post-natal bone formation.
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Albright, Thomas P., Denis Mutiibwa, Alexander R. Gerson, Eric Krabbe Smith, William A. Talbot, Jacqueline J. O’Neill, Andrew E. McKechnie, and Blair O. Wolf. "Mapping evaporative water loss in desert passerines reveals an expanding threat of lethal dehydration." Proceedings of the National Academy of Sciences 114, no. 9 (February 13, 2017): 2283–88. http://dx.doi.org/10.1073/pnas.1613625114.
Повний текст джерелаАнотація:
Extreme high environmental temperatures produce a variety of consequences for wildlife, including mass die-offs. Heat waves are increasing in frequency, intensity, and extent, and are projected to increase further under climate change. However, the spatial and temporal dynamics of die-off risk are poorly understood. Here, we examine the effects of heat waves on evaporative water loss (EWL) and survival in five desert passerine birds across the southwestern United States using a combination of physiological data, mechanistically informed models, and hourly geospatial temperature data. We ask how rates of EWL vary with temperature across species; how frequently, over what areas, and how rapidly lethal dehydration occurs; how EWL and die-off risk vary with body mass; and how die-off risk is affected by climate warming. We find that smaller-bodied passerines are subject to higher rates of mass-specific EWL than larger-bodied counterparts and thus encounter potentially lethal conditions much more frequently, over shorter daily intervals, and over larger geographic areas. Warming by 4 °C greatly expands the extent, frequency, and intensity of dehydration risk, and introduces new threats for larger passerine birds, particularly those with limited geographic ranges. Our models reveal that increasing air temperatures and heat wave occurrence will potentially have important impacts on the water balance, daily activity, and geographic distribution of arid-zone birds. Impacts may be exacerbated by chronic effects and interactions with other environmental changes. This work underscores the importance of acute risks of high temperatures, particularly for small-bodied species, and suggests conservation of thermal refugia and water sources.
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Bederman, Ilya R., Nicola Lai, Jeffrey Shuster, Leigh Henderson, Steven Ewart, and Marco E. Cabrera. "Chronic hindlimb suspension unloading markedly decreases turnover rates of skeletal and cardiac muscle proteins and adipose tissue triglycerides." Journal of Applied Physiology 119, no. 1 (July 1, 2015): 16–26. http://dx.doi.org/10.1152/japplphysiol.00004.2014.
Повний текст джерелаАнотація:
We previously showed that a single bolus of “doubly-labeled” water (2H218O) can be used to simultaneously determine energy expenditure and turnover rates (synthesis and degradation) of tissue-specific lipids and proteins by modeling labeling patterns of protein-bound alanine and triglyceride-bound glycerol (Bederman IR, Dufner DA, Alexander JC, Previs SF. Am J Physiol Endocrinol Metab 290: E1048–E1056, 2006). Using this novel method, we quantified changes in the whole body and tissue-specific energy balance in a rat model of simulated “microgravity” induced by hindlimb suspension unloading (HSU). After chronic HSU (3 wk), rats exhibited marked atrophy of skeletal and cardiac muscles and significant decrease in adipose tissue mass. For example, soleus muscle mass progressively decreased 11, 43, and 52%. We found similar energy expenditure between control (90 ± 3 kcal·kg−1·day−1) and hindlimb suspended (81 ± 6 kcal/kg day) animals. By comparing food intake (∼112 kcal·kg−1·day−1) and expenditure, we found that animals maintained positive calorie balance proportional to their body weight. From multicompartmental fitting of 2H-labeling patterns, we found significantly ( P < 0.005) decreased rates of synthesis (percent decrease from control: cardiac, 25.5%; soleus, 70.3%; extensor digitorum longus, 44.9%; gastrocnemius, 52.5%; and adipose tissue, 39.5%) and rates of degradation (muscles: cardiac, 9.7%; soleus, 52.0%; extensor digitorum longus, 27.8%; gastrocnemius, 37.4%; and adipose tissue, 50.2%). Overall, HSU affected growth of young rats by decreasing the turnover rates of proteins in skeletal and cardiac muscles and adipose tissue triglycerides. Specifically, we found that synthesis rates of skeletal and cardiac muscle proteins were affected to a much greater degree compared with the decrease in degradation rates, resulting in large negative balance and significant tissue loss. In contrast, we found a small decrease in adipose tissue triglyceride synthesis paired with a large decrease in degradation, resulting in smaller negative energy balance and loss of fat mass. We conclude that HSU in rats differentially affects turnover of muscle proteins vs. adipose tissue triglycerides.
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Charbonnier, Julie, Jacquelyn Pearlmutter, James Vonesh, Caitlin Gabor, Zachery Forsburg, and Kristine Grayson. "Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander." Diversity 10, no. 3 (July 19, 2018): 68. http://dx.doi.org/10.3390/d10030068.
Повний текст джерелаАнотація:
For organisms with complex life cycles, conditions experienced during early life stages may constrain later growth and survival. Conversely, compensatory mechanisms may attenuate negative effects from early life stages. We used the spotted salamander, Ambystoma maculatum, to test how aquatic larval density and terrestrial moisture influence juvenile growth, food intake, evaporative water loss and water reuptake rates, and corticosterone levels. We conducted an outdoor mesocosm experiment to manipulate larval density and transferred metamorphosed salamanders into low and high terrestrial moisture treatments in laboratory terrariums. After the larval stage, high-density salamanders were significantly smaller and had higher corticosterone release rates than those from low-density treatments. Salamanders in the low terrestrial moisture treatment consumed fewer roaches, had lower mass-specific growth rates, higher water reuptake, and higher corticosterone release rates than salamanders in high terrestrial moisture treatments. Across moisture treatments, smaller salamanders had higher mass-specific growth rates than larger salamanders. Our results suggest that salamanders can partially compensate for competition in the larval aquatic habitat with increased growth as juveniles, but this response is dependent on terrestrial habitat quality. Thus, the persistence of early life stage effects can be an important, yet context-dependent, component of amphibian life cycles.
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Sefton, Christine A., Kelvin Montagu, Brian J. Atwell, and Jann P. Conroy. "Anatomical variation in juvenile eucalypt leaves accounts for differences in specific leaf area and CO2 assimilation rates." Australian Journal of Botany 50, no. 3 (2002): 301. http://dx.doi.org/10.1071/bt01059.
Повний текст джерелаАнотація:
Specific leaf area (SLA) is an important leaf attribute representing a compromise between the capture of light and CO2 and the limitations imposed by leaf structure, herbivore resistance and the mitigation of water loss. We examined three Eucalyptus L'Her. species to determine whether variation in CO2 assimilation rate was related to SLA and leaf anatomy. Seedlings were grown in a naturally illuminated glasshouse with adequate water and nutrients. Light-saturated rates of photosynthesis were measured on the youngest fully expanded leaves. Mesophyll characteristics were measured from sections thick of the interveinal leaf lamina. Significant interspecies variation in SLA corresponded to clear trends in anatomy and photosynthesis. Low-SLA leaves were thicker, having increased thickness of palisade mesophyll because of a greater number of palisade layers. E. occidentalis, E.camaldulensis and E. grandis had 3.7, 2.0 and 1.0 layers of palisade cells which corresponded to an SLA of 14.8, 17.6 and 21.8 m2 kg-1, respectively. High investment of dry mass in photosynthetic tissue was associated with higher leaf N (area and mass) concentration, chlorophyll concentration and photosynthetic capacity per leaf area. Leaf morphology affected use of the resources N, water and CO2. In contrast to the thin leaves of E. grandis, thick leaves of E. occidentalis had low N-use efficiency and high instantaneous water-use efficiency. Differences in leaf structure of these species appear to reflect the most limiting resource experienced in the environments to which they have adapted.
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Prudnikova, Svetlana V. "Microbiological Degradation of Poly(3-Hydroxybutyrate) Films in Different Edaphoclimatic Zones of Siberia." Journal of Siberian Federal University. Biology 14, no. 4 (December 2021): 533–40. http://dx.doi.org/10.17516/1997-1389-0370.
Повний текст джерелаАнотація:
The urgency of handling plastic waste is escalating every year and the problem can be only solved using an integrated approach. Replacing non-degradable materials synthesised from fossil fuels with carbon-neutral biopolymers can reduce non-biodegradable waste, CO2 emissions and energy use. However, even completely biodegradable biopolymer materials will stay in the environment for a long time since the rate of their biodegradation depends on many factors. The paper evaluates the influence of edaphoclimatic and microbiological factors on the biodegradation rate of biopolymer films from the poly(3-hydroxybutyrate) [P(3HB)] when exposed to soddy-carbonate, cryogenic, and agrogenically transformed Siberian soils. A principal component analysis showed that in different soils, characterised by specific temperature, moisture content, pH values, biogenicity and abundance of microorganisms, the kinetics of mass loss of P(3HB)-films were primarily determined by the temperature- precipitation ratio and it increased as the content of humus in soil increased. The maximum rates of film mass loss of 0.63 ± 0.09 and 0.93 ± 0.01 mg ∙ day-1 were detected in agrogenic soils. No correlation between mass loss of the films and the total number of microorganisms was found. A phylogenetic analysis revealed differences in the composition of primary P(3HB)-degrading microorganisms in different soil types
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Jefferson, Leonard S., and Scot R. Kimball. "Translational Control of Protein Synthesis: Implications for Understanding Changes in Skeletal Muscle Mass." International Journal of Sport Nutrition and Exercise Metabolism 11, s1 (December 2001): S143—S149. http://dx.doi.org/10.1123/ijsnem.11.s1.s143.
Повний текст джерелаАнотація:
Gain or loss of skeletal muscle mass is due largely to the establishment of an imbalance between rates of protein synthesis and degradation. A key determinant of the rate of protein synthesis is translation initiation, a process regulated in part through binding of initiator methionyl-tRNA (met-tRNAi) and messenger RNA (mRNA) to a 40S ribosomal subunit. Either the met-tRNAi or mRNA binding step can become limiting for protein synthesis. Furthermore, the mRNA binding step can modulate translation of specific mRNAs with or without changes in the overall rate of protein synthesis. This report highlights molecular mechanisms involved in mediating control of the mRNA binding step in translation initiation. Particular attention is given to the effect of exercise on this step and to how the branched-chain amino acid leucine stimulates muscle protein synthesis after exercise. Potential mechanisms for exercise induced increase in muscle mass are discussed.
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Lützgendorf, Nora, Markus Kissler-Patig, Karl Gebhardt, Holger Baumgardt, Diederik Kruijssen, Eva Noyola, Nadine Neumayer, et al. "Intermediate-mass black holes in globular clusters: observations and simulations." Proceedings of the International Astronomical Union 10, S312 (August 2014): 181–88. http://dx.doi.org/10.1017/s1743921315007784.
Повний текст джерелаАнотація:
AbstractThe study of intermediate-mass black holes (IMBHs) is a young and promising field of research. If IMBHs exist, they could explain the rapid growth of supermassive black holes by acting as seeds in the early stage of galaxy formation. Formed by runaway collisions of massive stars in young and dense stellar clusters, intermediate-mass black holes could still be present in the centers of globular clusters, today. Our group investigated the presence of intermediate-mass black holes for a sample of 10 Galactic globular clusters. We measured the inner kinematic profiles with integral-field spectroscopy and determined masses or upper limits of central black holes in each cluster. In combination with literature data we further studied the positions of our results on known black-hole scaling relations (such as M• − σ) and found a similar but flatter correlation for IMBHs. Applying cluster evolution codes, the change in the slope could be explained with the stellar mass loss occurring in clusters in a tidal field over its life time. Furthermore, we present results from several numerical simulations on the topic of IMBHs and integral field units (IFUs). We ran N-body simulations of globular clusters containing IMBHs in a tidal field and studied their effects on mass-loss rates and remnant fractions and showed that an IMBH in the center prevents core collapse and ejects massive objects more rapidly. These simulations were further used to simulate IFU data cubes. For the specific case of NGC 6388 we simulated two different IFU techniques and found that velocity dispersion measurements from individual velocities are strongly biased towards lower values due to blends of neighboring stars and background light. In addition, we use the Astrophysical Multipurpose Software Environment (AMUSE) to combine gravitational physics, stellar evolution and hydrodynamics to simulate the accretion of stellar winds onto a black hole.
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Collins, Daniel P., Warren C. Conway, Corey D. Mason, and Jeffrey W. Gunnels. "Decomposition of Three Common Moist-Soil Managed Wetland Plant Species." Journal of Fish and Wildlife Management 6, no. 1 (January 1, 2015): 102–11. http://dx.doi.org/10.3996/072013-jfwm-050.
Повний текст джерелаАнотація:
Abstract Moist-soil wetland management is used to precisely control delivery, duration, and timing of water addition to, and removal from, managed wetlands with targeted responses including germination and growth of desirable moist-soil plant species. Similarly, water delivery and removal drives decomposition of moist-soil plants as well as nutrient cycling within these systems, which is a key driver of productivity in such managed wetlands. Through deployment of litter bags, we examined rate of mass loss and decay coefficients of three locally abundant moist-soil annual species that are potentially valuable wintering-waterfowl food sources (nodding smartweed Persicaria lapathifolia, red-rooted flatnut sedge Cyperus erythrorhizos, and toothcup Ammannia coccinea) within man-made moist-soil managed wetlands on the Richland Creek Wildlife Management Area in East-central Texas. All three species lost nearly 100% of their mass during an 11-mo deployment period, where rate of mass lost and decay coefficient rates were driven by time, because all moist-soil managed wetlands used were inundated for the duration of this study. Plant materials exposed to persistent inundation in shallow wetlands exhibited rates of mass loss typical of the first two stages of decomposition, during which a majority of plant material mass was lost. However, during this study, typical inundation and drawdown regimes were not implemented, which may have delayed or prolonged decomposition processes, because litter bags of focal species were inundated for the duration of this study. Both locally and regionally specific moist-soil management hydroperiod manipulation should include both drawdown and inundation, to incorporate temporal transitions between these conditions. Such practices will allow wetland managers to more expeditiously meet plant management and waterfowl food production goals within moist-soil managed wetlands.
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Zahn, Andreas, Lothar Ebner, Kurt Winkler, Jan Kratochvíl, and Jindřich Zahradník. "The effect of two-phase flow regime on hydrodynamics and mass transfer in a horizontal-tube gas-liquid reactor." Collection of Czechoslovak Chemical Communications 50, no. 3 (1985): 745–57. http://dx.doi.org/10.1135/cccc19850745.
Повний текст джерелаАнотація:
The effect of two-phase flow regime on decisive hydrodynamic and mass transfer characteristics of horizontal-tube gas-liquid reactors (pressure drop, liquid holdup, kLaL) was determined in a cocurrent-flow experimental unit of the length 4.15 m and diameter 0.05 m with air-water system. An adjustable-height weir was installed in the separation chamber at the reactor outlet to simulate the effect of internal baffles on reactor hydrodynamics. Flow regime maps were developed in the whole range of experimental gas and liquid flow rates both for the weirless arrangement and for the weir height 0.05 m, the former being in good agreement with flow-pattern boundaries presented by Mandhane. In the whole range of experi-mental conditions pressure drop data could be well correlated as a function of gas and liquid flow rates by an empirical exponential-type relation with specific sets of coefficients obtained for individual flow regimes from experimental data. Good agreement was observed between values of pressure drop obtained for weirless arrangement and data calculated from the Lockhart-Martinelli correlation while the contribution of weir to the overall pressure drop was well described by a relation proposed for the pressure loss in closed-end tubes. In the region of negligible weir influence values of liquid holdup were again succesfully correlated by the Lockhart-Martinelli relation while the dependence of liquid holdup data on gas and liquid flow rates obtained under conditions of significant weir effect (i.e. at low flow rates of both phases) could be well described by an empirical exponential-type relation. Results of preliminary kLaL measurements confirmed the decisive effect of the rate of energy dissipation on the intensity of interfacial mass transfer in gas-liquid dispersions.
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Somigliana, Alice, Claudia Toci, Giuseppe Lodato, Giovanni Rosotti, and Carlo F. Manara. "Effects of photoevaporation on protoplanetary disc ‘isochrones’." Monthly Notices of the Royal Astronomical Society 492, no. 1 (December 11, 2019): 1120–26. http://dx.doi.org/10.1093/mnras/stz3481.
Повний текст джерелаАнотація:
ABSTRACT Protoplanetary discs are the site of star and planet formation, and their evolution and consequent dispersal deeply affect the formation of planetary systems. In the standard scenario they evolve on time-scales ∼Myr due to the viscous transport of angular momentum. The analytical self-similar solution for their evolution predicts specific disc isochrones in the accretion rate–disc mass plane. However, photoevaporation by radiation emitted by the central star is likely to dominate the gas disc dispersal of the innermost region, introducing another (shorter) time-scale for this process. In this paper, we include the effect of internal (X and EUV) photoevaporation on the disc evolution, finding numerical solutions for a population of protoplanetary discs. Our models naturally reproduce the expected quick dispersal of the inner region of discs when their accretion rates match the rate of photoevaporative mass loss, in line with previous studies. We find that photoevaporation preferentially removes the lightest discs in the sample. The net result is that, counter-intuitively, photoevaporation increases the average disc mass in the sample, by dispersing the lightest discs. At the same time, photoevaporation also reduces the mass accretion rate by cutting the supply of material from the outer to the inner disc. In a purely viscous framework, this would be interpreted as the result of a longer viscous evolution, leading to an overestimate of the disc age. Our results thus show that photoevaporation is a necessary ingredient to include when interpreting observations of large disc samples with measured mass accretion rates and disc masses. Photoevaporation leaves a characteristic imprint on the shape of the isochrone. Accurate data of the accretion rate–disc mass plane in the low disc mass region therefore give clues on the typical photoevaporation rate.
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Seehaus, Thorsten, Philipp Malz, Christian Sommer, Stefan Lippl, Alejo Cochachin, and Matthias Braun. "Changes of the tropical glaciers throughout Peru between 2000 and 2016 – mass balance and area fluctuations." Cryosphere 13, no. 10 (September 30, 2019): 2537–56. http://dx.doi.org/10.5194/tc-13-2537-2019.
Повний текст джерелаАнотація:
Abstract. Glaciers in tropical regions are very sensitive to climatic variations and thus strongly affected by climate change. The majority of the tropical glaciers worldwide are located in the Peruvian Andes, which have shown significant ice loss in the last century. Here, we present the first multi-temporal, region-wide survey of geodetic mass balances and glacier area fluctuations throughout Peru covering the period 2000–2016. Glacier extents are derived from Landsat imagery by performing automatic glacier delineation based on a combination of the NDSI and band ratio method and final manual inspection and correction. The mapping of debris-covered glacier extents is supported by synthetic aperture radar (SAR) coherence information. A total glacier area loss of -548.5±65.7 km2 (−29 %, −34.3 km2 a−1) is obtained for the study period. Using interferometric satellite SAR acquisitions, bi-temporal geodetic mass balances are derived. An average specific mass balance of -296±41 kg m−2 a−1 is found throughout Peru for the period 2000–2016. However, there are strong regional and temporal differences in the mass budgets ranging from 45±97 to -752±452 kg m−2 a−1. The ice loss increased towards the end of the observation period. Between 2013 and 2016, a retreat of the glacierized area of -203.8±65.7 km2 (−16 %, −101.9 km2 a−1) is mapped and the average mass budget amounts to -660±178 kg m−2 a−1. The glacier changes revealed can be attributed to changes in the climatic settings in the study region, derived from ERA-Interim reanalysis data and the Oceanic Nino Index. The intense El Niño activities in 2015/16 are most likely the trigger for the increased change rates in the time interval 2013–2016. Our observations provide fundamental information on the current dramatic glacier changes for local authorities and for the calibration and validation of glacier change projections.
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Fromme, Tobias, Christoph Hoffmann, Kerstin Nau, Jan Rozman, Kathrin Reichwald, Michael Utting, Matthias Platzer, and Martin Klingenspor. "An intronic single base exchange leads to a brown adipose tissue-specific loss of Ucp3 expression and an altered body mass trajectory." Physiological Genomics 38, no. 1 (June 2009): 54–62. http://dx.doi.org/10.1152/physiolgenomics.00249.2007.
Повний текст джерелаАнотація:
Uncoupling protein 3 (Ucp3) is a transport protein of the inner mitochondrial membrane and presumably is implicated in the maintenance or tolerance of high lipid oxidation rates. Ucp3 is predominantly expressed in skeletal muscle and brown adipose tissue and is regulated by a transcription factor complex involving peroxisome proliferator-activated receptor-α, MyoD, and COUP transcription factor II. By analysis of a mutant Djungarian hamster model lacking Ucp3 transcription specifically in brown adipose tissue, we identified a putative transcription factor-binding site that confers tissue specificity. A naturally occurring intronic point mutation disrupting this site leads to brown adipose tissue-specific loss of Ucp3 expression and an altered body weight trajectory. Our findings provide insight into tissue-specific Ucp3 regulation and, for the first time, unambiguously demonstrate that changes in Ucp3 expression can interfere with body weight regulation.
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Anderson, James M., Emily Spurgeon, Brian S. Stirling, Jack May, Patrick T. Rex, Bobby Hyla, Steve McCullough, Marten Thompson, and Christopher G. Lowe. "High resolution acoustic telemetry reveals swim speeds and inferred field metabolic rates in juvenile white sharks (Carcharodon carcharias)." PLOS ONE 17, no. 6 (June 9, 2022): e0268914. http://dx.doi.org/10.1371/journal.pone.0268914.
Повний текст джерелаАнотація:
White sharks (Carcharodon carcharias) are the largest shark species to display regional endothermy. This capability likely facilitates exploitation of resources beyond thermal tolerance thresholds of potential sympatric competitors as well as sustained elevated swim speeds, but results in increased metabolic costs of adults, which has been documented in different studies. Little, however, is known of the metabolic requirements in free-swimming juveniles of the species, due to their large size at birth and challenges in measuring their oxygen consumption rates in captivity. We used trilateration of positional data from high resolution acoustic-telemetry to derive swim speeds from speed-over-ground calculations for eighteen free-swimming individual juvenile white sharks, and subsequently estimate associated mass-specific oxygen consumption rates as a proxy for field routine metabolic rates. Resulting estimates of mass-specific field routine metabolic rates (368 mg O2 kg−1 h−1 ± 27 mg O2 kg−1 h−1 [mean ± S.D.]) are markedly lower than those reported in sub-adult and adult white sharks by previous studies. We argue that median cruising speeds while aggregating at nearshore nursery habitats (0.6 m s-1 [mean ± S.E = 0.59 ± 0.001], 0.3 TL s-1) are likely a feature of behavioral strategies designed to optimize bioenergetic efficiency, by modulating activity rates in response to environmental temperature profiles to buffer heat loss and maintain homeostasis. Such behavioral strategies more closely resemble those exhibited in ectotherm sharks, than mature conspecifics.
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Zemp, Michael, Holger Frey, Isabelle Gärtner-Roer, Samuel U. Nussbaumer, Martin Hoelzle, Frank Paul, Wilfried Haeberli, et al. "Historically unprecedented global glacier decline in the early 21st century." Journal of Glaciology 61, no. 228 (2015): 745–62. http://dx.doi.org/10.3189/2015jog15j017.
Повний текст джерелаАнотація:
AbstractObservations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (∼42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (∼5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.
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Gibbs, A. G., A. K. Louie, and J. A. Ayala. "Effects of temperature on cuticular lipids and water balance in a desert Drosophila: is thermal acclimation beneficial?" Journal of Experimental Biology 201, no. 1 (January 1, 1998): 71–80. http://dx.doi.org/10.1242/jeb.201.1.71.
Повний текст джерелаАнотація:
The desert fruit fly Drosophila mojavensis experiences environmental conditions of high temperature and low humidity. To understand the physiological mechanisms allowing these small insects to survive in such stressful conditions, we studied the effects of thermal acclimation on cuticular lipids and rates of water loss of adult D. mojavensis. Mean hydrocarbon chain length increased at higher temperatures, but cuticular lipid melting temperature (Tm) did not. Lipid quantity doubled in the first 14 days of adult life, but was unaffected by acclimation temperature. Despite these changes in cuticular properties, organismal rates of water loss were unaffected by either acclimation temperature or age. Owing to the smaller body size of warm-acclimated flies, D. mojavensis reared for 14 days at 33 degrees C lost water more rapidly on a mass-specific basis than flies acclimated to 25 degrees C or 17 degrees C. Thus, apparently adaptive changes in cuticular lipids do not necessarily result in reduced rates of water loss. Avoidance of high temperatures and desiccating conditions is more likely to contribute to survival in nature than changes in water balance mediated by surface lipids.
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Piene, Harald. "Growth recovery in young, plantation white spruce following artificial defoliation and pruning." Canadian Journal of Forest Research 33, no. 7 (July 1, 2003): 1267–75. http://dx.doi.org/10.1139/x03-051.
Повний текст джерелаАнотація:
Defoliation by the spruce budworm (Choristoneura fumiferana (Clem.)) was simulated by artificially defoliating trees in a plantation of 12-year-old white spruce (Picea glauca (Moench) Voss) over a 2-year period and then allowing the trees to recover for 3 years. Four treatments were applied: control (C); removal of 50% of the current-year foliage (50); removal of all current-year shoots (100P); and removal of all current-year shoots and some older foliage age-classes (100P+). All treatments increased shoot production. Trees in the 100P treatment completely recovered their foliage mass after 1 year, but trees in the 50 treatment were still affected after 3 years of recovery. Trees in the 100P+ treatment showed poor recovery rates in foliage mass. Only the trees in the 50 treatment completely recovered height growth. After 2 years of defoliation, specific volume increment was reduced by 21.3, 58.1, and 75.3% for the 50, 100P, and 100P+ treatments, respectively. After 3 years of recovery, specific volume increment in the 50 treatment recovered completely, while the 100P and 100P+ treatments were reduced by 34.2 and 79.9%, respectively. Because of the release of suppressed buds following both needle loss only and shoot loss, white spruce may be a reforestation candidate for areas having a high probability of budworm outbreaks.
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Altinci, Pinar, Roda Seseogullari-Dirihan, Gulsen Can, David Pashley, and Arzu Tezvergil-Mutluay. "Zinc Inhibits Collagenolysis by Cathepsin K and Matrix Metalloproteinases in Demineralized Dentin Matrix." Caries Research 51, no. 6 (2017): 576–81. http://dx.doi.org/10.1159/000479896.
Повний текст джерелаАнотація:
The enzymatic degradation of dentin organic matrix occurs via both the action of matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs). Zinc can prevent collagen hydrolysis by MMPs. However, its effect on the activity of dentin-bound CCs is not known. The aim of this study was to investigate the effect of zinc on matrix-bound cathepsin K and MMP activity in dentin. Completely demineralized dentin beams were divided into test groups (n = 9) and incubated at 37°C in an incubation media (1 mL) containing ZnCl2 of 0.02 (physiological level, control), 0.2, 0.5, 1, 5, 10, 20, 30, or 40 mM. The dry mass changes of the beams were determined, and incubation media were analyzed for cathepsin K- and MMP-specific collagen degradation end products - CTX (C-terminal cross-linked telopeptide of type I collagen) and ICTP (cross-linked carboxy-terminal telopeptide of type I collagen) - at 1, 3, and 7 days of incubation. The mass loss of the beams decreased when the zinc level in the incubation media was ≥5 mM (p < 0.05). The release of liberated collagen degradation telopeptides decreased in accordance with the decrease in the mass loss rates of the beams. Cathepsin K-induced dentin collagen degradation can be strongly inhibited by zinc. Zinc levels of ≥5 mM can be considered as a reliable threshold for the stabilization of dentin matrices.
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Antony, Marie Lue, Klara Noble-Orcutt, Oluwateniayo Ogunsan, Fiona He, and Zohar Sachs. "Cell Type-Specific Effects of Crizotinib in Human Acute Myeloid Leukemia with TP53 Alterations." Blood 134, Supplement_1 (November 13, 2019): 2563. http://dx.doi.org/10.1182/blood-2019-130487.
Повний текст джерелаАнотація:
Introduction: In acute myeloid leukemia (AML) standard therapies induce complete remission in 50-70% of patients, but overall two-year survival is less than 20-30% because of high relapse rates. AML with TP53 alteration is largely insensitive to chemotherapy, modern targeted agents, and hematopoietic stem cell transplantation. Mutations in TP53 are seen in approximately 20% of AML and confer a particularly poor prognosis decreasing the 1-2 year survival rates to 0-10%. Leukemia stem cells (LSCs) are defined as the cells that recapitulate the leukemia and cause relapse. Recent large-scale drug-screening efforts to map treatment vulnerabilities in AML have revealed that crizotinib can reduce the in vitro viability of unselected primary human AML bone marrow samples with TP53 alterations (Tyner et al. Nature 2018). Crizotinib is a tyrosine kinase inhibitor that targets ALK, MET, and RON and is FDA approved for treatment of lung cancer. Since LSCs are largely responsible for AML mortality, we investigated whether crizotinib targets LSCs in primary, diagnostic human AML samples with TP53 alterations. We used mass cytometry (CyTOF2) to determine the cell-type specific effects of this drug on intracellular signaling states. We profiled treated samples with a panel that includes immunophenotypic markers (including LSC markers) and intracellular signaling molecules implicated in AML pathogenesis and aggressiveness. Results: Primary human AML samples with TP53 alterations were treated with crizotinib (10 mM, n=3). There was a reduction of viability by 48 hours of in vitro treatment with crizotinib, relative to vehicle (mean 64% reduction in viability). Crizotinib abolished all colony formation in semi-solid media. Mass cytometry analysis revealed that crizotinib treatment led to a loss of cells bearing LSC-specific markers such as CD123 and TIM3. Crizotinib treatment also induced a consistent loss of phosphorylated-signaling intermediates of the STAT and p38/MAPAPKII pathways in all samples tested. Notably, crizotinib treatment also induced significant reductions in total and phosphorylated NFKB in all samples tested. Conclusions: These data reveal cell-type specific effects of crizotinib in human AML with TP53 alterations. Crizotinib induced a specific loss of LSCs and inhibition of the STAT, p38/MAPAPKII and NFKB pathways. These data suggest that crizotinib inhibition may target LSCs in AML with TP53 alterations. Figure Disclosures No relevant conflicts of interest to declare.
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Trujillo-Gomez, Sebastian, J. M. Diederik Kruijssen, and Marta Reina-Campos. "The emergence of dark matter-deficient ultra-diffuse galaxies driven by scatter in the stellar mass–halo mass relation and feedback from globular clusters." Monthly Notices of the Royal Astronomical Society 510, no. 3 (December 1, 2021): 3356–78. http://dx.doi.org/10.1093/mnras/stab3401.
Повний текст джерелаАнотація:
ABSTRACT In addition to their low stellar densities, ultra-diffuse galaxies (UDGs) have a broad variety of dynamical mass-to-light ratios, ranging from dark matter (DM) dominated systems to objects nearly devoid of DM. To investigate the origin of this diversity, we develop a simple, semi-empirical model that predicts the structural evolution of galaxies, driven by feedback from massive star clusters, as a function of their departure from the mean SMHM relation. The model predicts that a galaxy located ≳ 0.5 dex above the mean relation at Mhalo = 1010 M⊙ will host a factor of ∼10–100 larger globular cluster (GC) populations, and that feedback from these GCs drives a significant expansion of the stellar component and loss of DM compared to galaxies on the SMHM relation. This effect is stronger in haloes that collapse earlier and have enhanced star formation rates at $z\gtrsim 2$, which leads to increased gas pressures, stellar clustering, and mean cluster masses, and significantly enhances the energy loading of galactic winds and its impact on the DM and stellar orbits. The impact on galaxy size and DM content can be large enough to explain observed galaxies that contain nearly the universal baryon fraction, as well as NGC 1052-DF2 and DF4 and other isolated UDGs that contain almost no DM. The trend of increasing galaxy size with GC specific frequency observed in galaxy clusters also emerges naturally in the model. Our predictions can be tested with large and deep surveys of the stellar and GC populations in dwarfs and UDGs. Because stellar clustering drives the efficiency of galactic winds, it may be a dominant factor in the structural evolution of galaxies and should be included as an essential ingredient in galaxy formation models.
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Jeyaprabha, C., S. Muralidharan, D. Jayaperumal, G. Venkatachari, and N. S. Rengaswamy. "Studies on corrosion inhibitors for oil‐well tubular material in acid environments." Anti-Corrosion Methods and Materials 45, no. 3 (June 1, 1998): 148–52. http://dx.doi.org/10.1108/00035599810216812.
Повний текст джерелаАнотація:
To reduce the corrosion of oil‐ and gas‐well equipment during acid treatment, the acid must be inhibited. The behaviour of N‐80 oilfield material in 15 per cent hydrochloric acid solution inhibited by different inhibitor formulations containing amine, ester and a quaternary ammonium compound was studied at 303K for five hours by the mass loss method. The corrosion rates were obtained by polarisation. Impedance studies were carried out to evaluate the performance of the inhibitor formulations. It was found that the formulation containing 3,000ppm amine, 1,000ppm ester and 1,000ppm quaternary ammonium compound was effective for the specific oil‐well tubular material.
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Cundy, William, Annika Theodoulou, Chi Ling, Jeganath Krishnan, and Christopher Wilson. "Blood Loss in Total Knee Arthroplasty." Journal of Knee Surgery 30, no. 05 (September 21, 2016): 452–59. http://dx.doi.org/10.1055/s-0036-1592147.
Повний текст джерелаАнотація:
AbstractPatients undergoing total knee arthroplasty (TKA) have expected blood loss during and after surgery. The morbidity associated with blood loss and the burden of blood transfusions in adult arthroplasty necessitates preoperative optimization as routine practice. Current literature remains inconclusive on which TKA surgical instrumentation techniques are effective in minimizing perioperative blood loss, and consequently lower transfusion rates. The primary objective of this retrospective review, of a prospective randomized cohort study, was to compare surgical and patient factors, and their influence on blood loss and transfusions rates, between one type of patient-specific instrumentation (PSI), navigated computer-assisted surgery (CAS), and conventional TKA surgical techniques.A cohort of 128 matched patients (38 PSI, 44 CAS, 46 conventional surgeries) were compared. Preoperative factors analyzed included; age, gender, body mass index, preoperative hemoglobin (Hb) (g/L), international normalized ratio, use of anticoagulants and comorbid bleeding diathesis. Maximal Hb drop and transfusion requirements were compared on day 1 to 3. Perioperative factors collected included: surgical time, tourniquet time, drain output, in situ drain time, order of tibia or femoral cut, and intraoperative loss from suction.The three groups did not differ on the preoperative patient demographics examined. The difference between preoperative Hb and the lowest postoperative Hb readings did not differ between study groups (p = 0.39).There are no statistically significant differences in blood loss when comparing PSI versus CAS versus conventional TKA. Although emerging evidence on PSI is encouraging, the PSI technique for TKA does not result in reduced blood loss. The study was registered with ClinicalTrials.gov: NCT01145157.
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Pradisty, Novia Arinda, A. Aldrie Amir, and Martin Zimmer. "Plant species- and stage-specific differences in microbial decay of mangrove leaf litter: the older the better?" Oecologia 195, no. 4 (February 9, 2021): 843–58. http://dx.doi.org/10.1007/s00442-021-04865-3.
Повний текст джерелаАнотація:
AbstractLeaf litter and its breakdown products represent an important input of organic matter and nutrients to mangrove sediments and adjacent coastal ecosystems. It is commonly assumed that old-grown stands with mature trees contribute more to the permanent sediment organic matter pool than younger stands. However, neither are interspecific differences in leaf decay rates taken into account in this assumption nor is our understanding of the underlying mechanisms or drivers of differences in leaf chemistry sufficient. This study examines the influence of different plant species and ontogenetic stage on the microbial decay of mangrove leaf litter. A litterbag experiment was conducted in the Matang Mangrove Forest Reserve, Malaysia, to monitor leaf litter mass loss, and changes in leaf litter chemistry and microbial enzyme activity. Four mangrove species of different morphologies were selected, namely the trees Rhizophora apiculata and Bruguiera parviflora, the fern Acrostichum aureum and the shrub Acanthus ilicifolius. Decay rates of mangrove leaf litter decreased from A. ilicifolius to R. apiculata to B. parviflora to A. aureum. Leaf litter mass, total phenolic content, protein precipitation capacity and phenol oxidase activity were found to decline rapidly during the early stage of decay. Leaf litter from immature plants differed from that of mature plants in total phenolic content, phenolic signature, protein precipitating capacity and protease activity. For R. apiculata, but not of the other species, leaf litter from immature plants decayed faster than the litter of mature plants. The findings of this study advance our understanding of the organic matter dynamics in mangrove stands of different compositions and ages and will, thus, prove useful in mangrove forest management.
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Austin, Amy T., M. Soledad Méndez, and Carlos L. Ballaré. "Photodegradation alleviates the lignin bottleneck for carbon turnover in terrestrial ecosystems." Proceedings of the National Academy of Sciences 113, no. 16 (April 4, 2016): 4392–97. http://dx.doi.org/10.1073/pnas.1516157113.
Повний текст джерелаАнотація:
A mechanistic understanding of the controls on carbon storage and losses is essential for our capacity to predict and mitigate human impacts on the global carbon cycle. Plant litter decomposition is an important first step for carbon and nutrient turnover, and litter inputs and losses are essential in determining soil organic matter pools and the carbon balance in terrestrial ecosystems. Photodegradation, the photochemical mineralization of organic matter, has been recently identified as a mechanism for previously unexplained high rates of litter mass loss in arid lands; however, the global significance of this process as a control on carbon cycling in terrestrial ecosystems is not known. Here we show that, across a wide range of plant species, photodegradation enhanced subsequent biotic degradation of leaf litter. Moreover, we demonstrate that the mechanism for this enhancement involves increased accessibility to plant litter carbohydrates for microbial enzymes. Photodegradation of plant litter, driven by UV radiation, and especially visible (blue–green) light, reduced the structural and chemical bottleneck imposed by lignin in secondary cell walls. In leaf litter from woody species, specific interactions with UV radiation obscured facilitative effects of solar radiation on biotic decomposition. The generalized effect of sunlight exposure on subsequent microbial activity, mediated by increased accessibility to cell wall polysaccharides, suggests that photodegradation is quantitatively important in determining rates of mass loss, nutrient release, and the carbon balance in a broad range of terrestrial ecosystems.
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Houle-Leroy, Philippe, Helga Guderley, John G. Swallow, and Theodore Garland. "Artificial selection for high activity favors mighty mini-muscles in house mice." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 284, no. 2 (February 1, 2003): R433—R443. http://dx.doi.org/10.1152/ajpregu.00179.2002.
Повний текст джерелаАнотація:
After 14 generations of selection for voluntary wheel running, mice from the four replicate selected lines ran, on average, twice as many revolutions per day as those from the four unselected control lines. To examine whether the selected lines followed distinct strategies in the correlated responses of the size and metabolic capacities of the hindlimb muscles, we examined mice from selected lines, housed for 8 wk in cages with access to running wheels that were either free to rotate (“wheel access” group) or locked (“sedentary”). Thirteen of twenty individuals in one selected line (line 6) and two of twenty in another (line 3) showed a marked reduction (∼50%) in total hindlimb muscle mass, consistent with the previously described expression of a small-muscle phenotype. Individuals with these “mini-muscles” were not significantly smaller in total body mass compared with line-mates with normal-sized muscles. Access to free wheels did not affect the relative mass of the mini-muscles, but did result in typical mammalian training effects for mitochondrial enzyme activities. Individuals with mini-muscles showed a higher mass-specific muscle aerobic capacity as revealed by the maximal in vitro rates of citrate synthase and cytochrome c oxidase. Moreover, these mice showed the highest activities of hexokinase and carnitine palmitoyl transferase. Females with mini-muscles showed the highest levels of phosphofructokinase, and males with mini-muscles the highest levels of pyruvate dehydrogenase. As shown by total muscle enzyme contents, the increase in mass-specific aerobic capacity almost completely compensated for the reduction caused by the “loss” of muscle mass. Moreover, the mini-muscle mice exhibited the lowest contents of lactate dehydrogenase and glycogen phosphorylase. Interestingly, metabolic capacities of mini-muscled mice resemble those of muscles after endurance training. Overall, our results demonstrate that during selection for voluntary wheel running, distinct adaptive paths that differentially exploit the genetic variation in morphological and physiological traits have been followed.
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Mitchell, Jennifer D., B. Graeme Lockaby, and Eve F. Brantley. "Influence of Chinese Privet (Ligustrum sinense) on Decomposition and Nutrient Availability in Riparian Forests." Invasive Plant Science and Management 4, no. 4 (December 2011): 437–47. http://dx.doi.org/10.1614/ipsm-d-11-00020.1.
Повний текст джерелаАнотація:
AbstractAs invasive species become increasingly abundant in forests, their presence may influence a number of key nutrient cycling processes. For example, Chinese privet has become well established in southeastern forests and continues to spread. Two studies, a multisite field investigation and a controlled approach on a single site, were conducted to examine the role of Chinese privet (Ligustrum sinense) on decomposition within riparian forests of the Georgia Piedmont. The field study also investigated the effects of privet presence on soil nitrogen (N) mineralization and microbial carbon and N immobilization. Both studies utilized a litterbag approach to examine how increasing proportions of privet in foliar litter influenced mass loss rates and nutrient dynamics. The field investigation included litterbags with representative proportions of the five dominant species from 16 sites. Litterbags in the controlled study were composed of specific levels of privet litter within bags (0, 10, 20, 30, 40, and 50% Chinese privet) as treatments. The litter quality of four native species was compared to Chinese privet in the controlled study. Both studies showed significant positive relationships between percentage of Chinese privet in litterbags and decomposition rates (2.6-fold rate increase with 30% privet in litterfall). Chinese privet leaf litter had lower lignin and cellulose concentrations, higher N concentrations, lower lignin : N ratios, and narrower C : N ratios than the native species. The positive relationship between mass loss rates and the proportion of Chinese privet in litter indicates that Chinese privet enhances decomposition rates as it becomes more abundant. During summer, N mineralization showed approximately a fivefold increase; during winter, microbial biomass N increased by approximately 30% on sites with the highest levels of privet in the understory. Consequently, C and N dynamics in Piedmont riparian forests were significantly influenced in direct proportion to the amount of privet present in the understory.
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Stuart, Wilma Powell, Marion E. Broome, Barbara A. Smith, and Michael Weaver. "An Integrative Review of Interventions for Adolescent Weight Loss." Journal of School Nursing 21, no. 2 (April 2005): 77–85. http://dx.doi.org/10.1177/10598405050210020401.
Повний текст джерелаАнотація:
The number of overweight adolescents aged 12–19 has tripled during the past 2 decades. Although health risks associated with obesity in adolescence and adulthood are well documented in the literature, little is known about the efficacy of interventions to reduce health risks of this group. The purpose of this study was to conduct a systematic review to describe the scope, domain, and effectiveness of weight loss interventions with overweight adolescents. English-language journal articles published in nursing, psychology, nutrition, medicine, and exercise physiology literature between 1980 and 2003 were retrieved. Seventeen studies using comparison or control groups and interventions directed at reductions in adolescent body mass index or body weight were identified. Descriptive findings of those studies are reported here. Five specific limitations of these studies emerged from the analysis of the interventions: the study findings have not been validated by replication, the samples failed to include adequate representation of Latino and African American male participants, family participation in studies has been inconsistent and infrequent, there is a need for attention to study dropout rates (with attrition reported as high as 45%), and there is a need for conceptual frameworks to guide the studies.
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Zampino, Marta, Majd AlGhatrif, Pei-Lun Kuo, Eleanor Marie Simonsick, and Luigi Ferrucci. "Longitudinal Changes in Resting Metabolic Rates with Aging Are Accelerated by Diseases." Nutrients 12, no. 10 (October 7, 2020): 3061. http://dx.doi.org/10.3390/nu12103061.
Повний текст джерелаАнотація:
Resting metabolic rate (RMR) declines with aging and is related to changes in health status, but how specific health impairments impact basal metabolism over time has been largely unexplored. We analyzed the association of RMR with 15 common age-related chronic diseases for up to 13 years of follow-up in a population of 997 participants to the Baltimore Longitudinal Study of Aging. At each visit, participants underwent measurements of RMR by indirect calorimetry and body composition by DEXA. Linear regression models and linear mixed effect models were used to test cross-sectional and longitudinal associations of RMR and changes in disease status. Cancer and diabetes were associated with higher RMR at baseline. Independent of covariates, prevalent COPD and cancer, as well as incident diabetes, heart failure, and CKD were associated with a steeper decline in RMR over time. Chronic diseases seem to have a two-phase association with RMR. Initially, RMR may increase because of the high cost of resiliency homeostatic mechanisms. However, as the reserve capacity becomes exhausted, a catabolic cascade becomes unavoidable, resulting in loss of total and metabolically active mass and consequent RMR decline.
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Ambrosi, E., L. Zampieri, F. Pintore, and A. Wolter. "Modelling multiwavelength emission of Ultra-luminous X-ray Sources accreting above the Eddington limit." Monthly Notices of the Royal Astronomical Society 509, no. 4 (November 10, 2021): 4694–712. http://dx.doi.org/10.1093/mnras/stab3240.
Повний текст джерелаАнотація:
ABSTRACT We model the multiwavelength properties of binaries accreting at super-critical rates with the aim to better understand the observational properties of Ultra-luminous X-ray Sources (ULXs). We calculate an extended grid of binary systems which evolve through Roche Lobe Overflow and undergo case A mass transfer from massive donors (up to 25 ${\rm M}_{\odot } \,$) on to massive black holes (BHs) (up to 100 ${\rm M}_{\odot } \,$). Angular momentum loss with the ejection of mass through an outflow is incorporated. We apply our super-Eddington accretion model to these systems, computing their evolutionary tracks on the colour–magnitude diagram (CMD) for the Johnson and Hubble Space Telescope photometric systems. We found that the tracks occupy specific positions on the CMD depending on the evolutionary stage of the donor and of the binary. Moreover, their shapes are similar, regardless the BH mass. More massive BHs lead to more luminous tracks. We additionally compute their optical-through-X-ray spectral energy distribution considering the effects of a Comptonizing corona that surrounds the innermost regions of the disc. We apply our model to four ULXs: NGC 4559 X-7, NGC 5204 X-1, Holmberg II X-1, and NGC 5907 ULX-2. We found that accretion on to BHs with mass in the range of 35–55 ${\rm M}_{\odot }$ is consistent with to the observational properties of these sources. We finally explore and discuss the possibility to extend our model also to ULXs powered by accreting pulsars (PULXs).
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Fan, Rui, Yuntao Hao, Qian Du, Jiawei Kang, Meihong Xu, and Yong Li. "Beneficial Effects of Walnut Oligopeptides on Muscle Loss in Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice: Focusing on Mitochondrial Function." Nutrients 14, no. 10 (May 13, 2022): 2051. http://dx.doi.org/10.3390/nu14102051.
Повний текст джерелаАнотація:
Aging-related muscle loss is a hallmark of aging and is the cause of some negative outcomes. An optimized diet and supplements have a positive effect in slowing down the process of muscle loss. This study was designed to evaluate the beneficial effects of walnut oligopeptides (WOPs) on aging-related muscle loss and explore the possible underlying mechanism in Senescence-Accelerated Mouse Prone 8 (SAMP8) Mice. SAMP8 mice were randomly divided into four groups (n = 15/group), including one group which was the SAMP8 age control group and three groups those were WOP intervention groups. Meanwhile, Senescence Accelerated Resistant Mouse 1 (SAMR1) mice (n = 12), which had normal senescence rates, were used as model controls. During the six-month intervention period, the age control and normal control groups were given sterilized water, while the three WOP intervention groups were given WOP solution with low (110 mg/kg·bw), medium (220 mg/kg·bw) and high concentrations (440 mg/kg·bw), respectively. The results showed that WOPs could significantly increase muscle mass and improve physical performance (wire hang and catwalk behavioral tests) in aging mice. Moreover, WOPs could significantly reduce the levels of IL-1β, IL-6 and TNF-α in serum and gastrocnemius tissues and increase the mitochondrial DNA content, as well as the expression levels of AMPK, PGC-1α, NRF-1 and TFAM in the gastrocnemius muscle of aging mice, which was speculated to be the specific mechanism related to mitochondrial function improvement and inflammation reduction. These results indicate that WOPs can improve aging-related muscle loss, in term of both muscle mass and physical performance, and WOP supplements seems to be potentially effective in elderly individuals.
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Papadopoulos, Lazaros, Zoi Terzopoulou, Dimitrios Bikiaris, Dimitra Patsiaoura, Kostantinos Chrissafis, Dimitrios Papageorgiou, and George Papageorgiou. "Synthesis and Characterization of In-Situ-Prepared Nanocomposites Based on Poly(Propylene 2,5-Furan Dicarboxylate) and Aluminosilicate Clays." Polymers 10, no. 9 (August 23, 2018): 937. http://dx.doi.org/10.3390/polym10090937.
Повний текст джерелаАнотація:
Poly(propylene 2,5-furan dicarboxylate) (PPF), or poly(trimethylene 2,5-furan dicarboxylate) (PTF), is a biobased alipharomatic polyester that is expected to replace its fossil-based terephthalate (PPT) and naphthate (PPN) homologues. PPF possesses exceptional gas barrier properties, but its slow crystallization rate might affect its success in specific applications in the future. Therefore, a series of PPF based nanocomposites with the nanoclays Cloisite®-Na (MMT), Cloisite®-20A (MMT 20A), and halloysite nanotubes (HNT) were synthesized via the in situ transterification and polycondensation method. The effect of the nanoclays on the structure, thermal, and crystallization properties of PPF was studied with several methods including infrared spectroscopy (IR), Nuclear Resonance Spectroscopy (1H-NMR), Wide Angle X-ray Diffraction (WAXD), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). The insertion of the nanofillers in the polymer matrix altered the crystallization rates, and TGA results showed good thermal stability, since no significant mass loss occurred up to 300 °C. Finally, the degradation mechanism was studied in depth with Pyrolysis-Gas Chromatography/Mass Spectroscopy, and it was found that β-scission is the dominant degradation mechanism.
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Wang, Ningxin, Spiro D. Jorga, Jeffery R. Pierce, Neil M. Donahue, and Spyros N. Pandis. "Particle wall-loss correction methods in smog chamber experiments." Atmospheric Measurement Techniques 11, no. 12 (December 12, 2018): 6577–88. http://dx.doi.org/10.5194/amt-11-6577-2018.
Повний текст джерелаАнотація:
Abstract. The interaction of particles with the chamber walls has been a significant source of uncertainty when analyzing results of secondary organic aerosol (SOA) formation experiments performed in Teflon chambers. A number of particle wall-loss correction methods have been proposed including the use of a size-independent loss rate constant, the ratio of suspended organic mass to that of a conserved tracer (e.g., sulfate seeds), and a size-dependent loss rate constant, etc. For complex experiments such as the chemical aging of SOA, the results of the SOA quantification analysis can be quite sensitive to the adopted correction method due to the evolution of the particle size distribution and the duration of these experiments. We evaluated the performance of several particle wall-loss correction methods for aging experiments of α-pinene ozonolysis products. Determining the loss rates from seed loss periods is necessary for this system because it is not clear when chemical reactions have been completed. Results from the OA ∕ sulfate ratio and the size-independent correction methods can be influenced significantly by the size dependence of the particle wall-loss process. Coagulation can also affect the particle size distribution, especially for particles with diameter less than 100 nm, thus introducing errors in the results of the wall-loss correction. The corresponding loss rate constants may vary from experiment to experiment, and even during a specific experiment. Friction between the Teflon chamber walls and non-conductive surfaces can significantly increase particle wall-loss rates and the chamber may require weeks to recover to its original condition. Experimental procedures are proposed for the characterization of particle losses during different stages of these experiments and the evaluation of corresponding particle wall-loss correction.
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Kolokythas, Konstantinos, Sravani Vaddi, Ewan O’Sullivan, Ilani Loubser, Arif Babul, Somak Raychaudhury, Patricio Lagos, and Thomas H. Jarrett. "The Complete Local-Volume Groups Sample – IV. Star formation and gas content in group-dominant galaxies." Monthly Notices of the Royal Astronomical Society 510, no. 3 (December 22, 2021): 4191–207. http://dx.doi.org/10.1093/mnras/stab3699.
Повний текст джерелаАнотація:
ABSTRACT Using multiband data, we examine the star formation activity of the nearby group-dominant early-type galaxies of the Complete Local-volume Groups Sample (CLoGS) and the relation between star formation, gas content, and local environment. Only a small fraction of the galaxies (13 per cent; 6/47) are found to be far-ultraviolet (FUV) bright, with FUV to near-infrared colours indicative of recent active star formation (NGC 252, NGC 924, NGC 940, NGC 1106, NGC 7252, and ESO 507-25). These systems are lenticulars presenting the highest FUV-specific star formation rates in the sample (sSFRFUV > 5 × 1013 yr−1), significant cold gas reservoirs [M(H2) = 0.5-61 × 108 M⊙], reside in X-ray faint groups, and none hosts a powerful radio active galactic nucleus (AGN) (P$_{1.4\mathrm{ GHz}}\, \lt 10^{23}$ W Hz−1). The majority of the group-dominant galaxies (87 per cent; 41/47) are FUV faint, with no significant star formation, classified in most cases as spheroids based on their position on the infrared star-forming main sequence (87 per cent; 46/53). Examining the relationships between radio power, SFRFUV, and stellar mass, we find a lack of correlation that suggests a combination of origins for the cool gas in these galaxies, including stellar mass loss, cooling from the intra-group medium (IGrM) or galaxy halo, and acquisition through mergers or tidal interactions. X-ray bright systems, in addition to hosting radio powerful AGN, have a range of SFRs but, with the exception of NGC 315, do not rise to the highest rates seen in the FUV bright systems. We suggest that central group galaxy evolution is linked to gas mass availability, with star formation favoured in the absence of a group-scale X-ray halo, but AGN jet launching is more likely in systems with a cooling IGrM.
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Zhao, Ruirui, Yong Liu, Deborah S. Page-Dumroese, R. Kasten Dumroese, and Kai Wang. "Enhancing Soil Quality of Short Rotation Forest Operations Using Biochar and Manure." Forests 13, no. 12 (December 8, 2022): 2090. http://dx.doi.org/10.3390/f13122090.
Повний текст джерелаАнотація:
Biochar and manure may be used to enhance soil quality and productivity for sustainable agriculture and forestry operations. However, the response of surface and belowground wood decomposition (i.e., soil processes) and nutrient flux to soil amendments is unknown, and more site-specific information about soil property responses is also essential. In a split-plot design, the soil was amended with three rates of manure (whole plot; 0, 3, and 9 Mg ha−1) and three rates of biochar (split-plot; 0, 2.5, and 10 Mg ha−1). Soil physical properties, nutrients, and enzyme activities were evaluated in two years. In addition, wood stakes of three species (poplar, triploid Populus tomentosa Carr.; aspen, Populus tremuloides Michx.; and pine, Pinus taeda L.) were installed both horizontally on the soil surface and vertically in the mineral soil to serve as an index of soil abiotic and biotic changes. Wood stake mass loss, nitrogen (N), phosphorus (P), and potassium (K) flux were tested. The high rate of both manure and biochar increased soil water content by an average of 18%, but the increase in total soil P, K, organic carbon (C) content, and enzyme activities were restricted to single sample dates or soil depths. Wood stakes decomposed faster according to stake location (mineral > surface) and species (two Populus > pine). On average, soil amendments significantly increased the mass loss of surface and mineral stakes by 18% and 5%, respectively, and it also altered wood stake nutrient cycling. Overall, the decomposition of standard wood stakes can be a great indicator of soil quality changes, and 10 Mg ha−1 of biochar alone or combined with 9 Mg ha−1 of manure can be used for long-term carbon sequestration in plantations with similar soil conditions to the present study.
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Tseng, Jill H., Kara Long Roche, Amelia M. Jernigan, Ritu Salani, Robert E. Bristow, and Amanda Nickles Fader. "Lifestyle and Weight Management Counseling in Uterine Cancer Survivors: A Study of the Uterine Cancer Action Network." International Journal of Gynecologic Cancer 25, no. 7 (September 2015): 1285–91. http://dx.doi.org/10.1097/igc.0000000000000475.
Повний текст джерелаАнотація:
ObjectiveThe purpose of this study was to examine the experiences, attitudes, and preferences of uterine cancer survivors with regard to weight and lifestyle counseling.Materials and MethodsMembers of the US Uterine Cancer Action Network of the Foundation for Women’s Cancer were invited to complete a 45-item, Web-based survey. Standard descriptive statistical methods and χ2 tests were used to analyze responses.ResultsOne hundred eighty (28.3%) uterine cancer survivors completed the survey. Median age was 58 years, 85% were white, and median survivorship period was 4.4 years. Most had stage I–II disease (69%) and were overweight or obese (65%). Eighty-nine percent of respondents received care by a gynecologic oncologist. Increased respondent body mass index was associated with decreased exercise frequency (P = 0.016). Only 50% of respondents underwent any weight/lifestyle counseling, with those living in the West and Southwest reporting the highest rates (70.8% and 69.2%, P = 0.011). Most who received counseling felt that discussions were motivating, performed in a sensitive manner, and did not undermine the patient–physician relationship. Specific recommendations were rarely offered; there were no reported referrals to weight loss programs or bariatric specialists, and few (6%) reported referrals to nutritionists. Respondents (85%) preferred their gynecologic oncologist address weight using direct, face-to-face counseling with specific recommendations regarding interventions and referral to specialists. Finally, self-reported overweight respondents experienced greater success with weight loss compared to those reporting obesity or morbid obesity (30.8% vs 15.8% vs 12.5%, P = 0.011).ConclusionsUterine cancer survivors reported high obesity, low activity rates, and a desire for substantive weight loss counseling from their gynecologic oncologists. Respondents suggested that current counseling practices are inadequate and incongruent with their needs. Further research to define optimal timing, interventional strategies, and specific recommendations for successful lifestyle changes in this population is warranted.
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Heise-Pavlov, Sigrid R., and Rhiana D. Meade. "Improving reliability of scat counts for abundance and distribution estimations of Lumholtz’s Tree-kangaroo (Dendrolagus lumholtzi) in its rainforest habitats." Pacific Conservation Biology 18, no. 3 (2012): 153. http://dx.doi.org/10.1071/pc130153.
Повний текст джерелаАнотація:
arboreal folivores, such as Lumholtz’s Tree-kangaroo (Dendrolagus lumholtzi) in Far North Queensland, Australia, scat counts seem to be the most promising ecological technique. However, the occurrence of Lumholtz’s Tree-kangaroos in seasonal rainforests with dense understory, a high diversity of coprophagous invertebrates and with sympatric folivores increases the probability of invalidating results based on scat surveys. This study investigates scat production and scat decomposition patterns to select diagnostic traits of Lumholtz’s Tree-kangaroo scats that can, under varying environmental conditions, assist in distinguishing between fresh and old scats to reduce false positive and false negative errors in species presence due to non- or/and misidentification of scats. Scat production rates of six captive Lumholtz’s Tree-kangaroos were highly variable resulting in different scat numbers and masses. Changes in scat size (mass and circumference), pH and the appearance of mould were monitored under different laboratory conditions and in forest trials. Under wet conditions scats gained mass until they reached an apparent plateau of 130% of their original mass. Scats under dry conditions lost up to 90% of their original mass. Changes in mass were accompanied by changes in circumference of scats. By Day 3 scats had developed signs of mould under laboratory conditions and showed an acidic pH. Field trials revealed a high loss of scats due primarily to their consumption by dung beetles (Scarabaeoidea). For studying Lumholtz’s Tree-kangaroos in their rainforest environment, scat surveys should be confined to dry periods to reduce the probability of false negative errors due to activity of coprophagous invertebrates. Additionally, only fresh scats of average size and with an acidic pH should be used to minimize the risk of misidentifying small sized scats from Red-legged Pademelons (Thylogale stigmatica) as tree-kangaroo scats. More studies on species-specific diagnostic traits of Lumholtz’s Tree-kangaroo scats are necessary to validate false negative and false positive errors in scat counts for this species.
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Carr, J. Rachel, Chris R. Stokes, and Andreas Vieli. "Recent progress in understanding marine-terminating Arctic outlet glacier response to climatic and oceanic forcing." Progress in Physical Geography: Earth and Environment 37, no. 4 (April 5, 2013): 436–67. http://dx.doi.org/10.1177/0309133313483163.
Повний текст джерелаАнотація:
Until relatively recently, it was assumed that Arctic ice masses would respond to climatic/oceanic forcing over millennia, but observations made during the past two decades have radically altered this viewpoint and have demonstrated that marine-terminating outlet glaciers can undergo dramatic dynamic change at annual timescales. This paper reviews the substantial progress made in our understanding of the links between marine-terminating Arctic outlet glacier behaviour and the ocean-climate system during the past 20 years, when many ice masses have rapidly lost mass. Specifically, we assess three primary climatic/oceanic controls on outlet glacier dynamics, namely air temperature, ocean temperature and sea ice concentrations, and discuss key linkages between them. Despite recent progress, significant uncertainty remains over the response of marine-terminating outlet glaciers to these forcings, most notably: (1) the spatial variation in the relative importance of each factor; (2), the contribution of glacier-specific factors to glacier dynamics; and (3) the limitations in our ability to accurately model marine-terminating outlet glacier behaviour. Our present understanding precludes us from identifying patterns of outlet glacier response to forcing that are applicable across the Arctic and we underscore the potential danger of extrapolating rates of mass loss from a small sample of study glaciers.
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Roemmich, James N., and Wayne E. Sinning. "Weight loss and wrestling training: effects on nutrition, growth, maturation, body composition, and strength." Journal of Applied Physiology 82, no. 6 (June 1, 1997): 1751–59. http://dx.doi.org/10.1152/jappl.1997.82.6.1751.
Повний текст джерелаАнотація:
Roemmich, James N., and Wayne E. Sinning. Weight loss and wrestling training: effects on nutrition, growth, maturation, body composition, and strength. J. Appl. Physiol. 82(6): 1751–1759, 1997.—Adolescent wrestlers ( n = 9, 15.4 yr) and recreationally active control adolescent males ( n = 7, 15.7 yr) were measured before, at the end (late season), and 3.5–4 mo after a wrestling season to assess the influence of dietary restriction on growth, maturation, body composition, protein nutrition, and muscular strength. Controls consumed adequate amounts of energy, carbohydrate (CHO), protein, and fat, and demonstrated normal gains in weight, fat mass (FM) and fat-free mass (FFM). Wrestlers consumed a high-CHO (61 ± 2% kcal), low-fat (24 ± 2% kcal) diet during the season but did not consume adequate energy (24.7 ± 3.5 kcal ⋅ kg−1⋅ day−1) or protein (0.9 g ⋅ kg−1⋅ day−1). Deficient dietary intake reduced prealbumin levels (26.0 ± 1.9 vs. 20.2 ± 0.9 mg/dl) and slowed the accrual of lean arm and thigh cross-sectional muscle areas (AXSECT, TXSECT, respectively). For wrestlers, dietary deficiency also decreased weight (60.3 ± 3.5 to 58.0 ± 3.3 kg), relative fat (9.9 ± 0.5 to 8.0 ± 0.7%), and FM (6.0 ± 0.5 to 4.7 ± 0.6 kg). Postseason, wrestlers and controls consumed similar diets, and wrestlers had significant increases in prealbumin, AXSECT, and TXSECT. Wrestlers also increased their weight (6.1 ± 0.6 kg), FFM (3.0 ± 0.6 kg), and FM (3.2 ± 0.5 kg) postseason. Rates of bone maturation and segmental growth were not different between the groups. The wrestlers had reductions in elbow and knee strength from preseason to late season but increases postseason. Lean tissue changes were associated with the changes in strength and power ( r = 0.72–0.91, P < 0.001). After covariance for FFM or limb-specific cross section, few significant changes remained. In conclusion, dietary restriction reduced protein nutrition and muscular performance but produced little effect on linear growth and maturation. Prealbumin levels and the rate of lean tissue accrual were positively related ( r = 0.43, P ≤ 0.05).
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Schrager, Matthew A., Stephen M. Roth, Robert E. Ferrell, E. Jeffrey Metter, Estelle Russek-Cohen, Nicole A. Lynch, Rosemary S. Lindle, and Ben F. Hurley. "Insulin-like growth factor-2 genotype, fat-free mass, and muscle performance across the adult life span." Journal of Applied Physiology 97, no. 6 (December 2004): 2176–83. http://dx.doi.org/10.1152/japplphysiol.00985.2003.
Повний текст джерелаАнотація:
The influence of insulin-like growth factor-2 ( IGF2) genotype on total body fat-free mass (FFM), muscle strength, and sustained power (SP) was evaluated repeatedly at ∼2-yr intervals in two cohorts from the Baltimore Longitudinal Study of Aging. Cohort 1 was comprised of 94 men tested for isometric grip strength and SP. Cohort 2 was comprised of 246 men and 239 women tested for total body FFM and isokinetic peak torque. Subjects were retrospectively genotyped for the IGF2 gene's ApaI polymorphism. Differences between genotype groups for total FFM, strength, and SP at first visit, at peak age (35 yr), at age 65, and across the adult age span were analyzed using either two-sample t-tests or mixed-effects models, depending on the specific comparisons made. Isokinetic arm strength at the time of first visit was lower in A/A men than in G/G men ( P < 0.05). Compared with G/G women, A/A women had lower total body FFM, lower isokinetic arm and leg strength at the time of first visit, and lower values at age 35 (all P < 0.05) for these muscle phenotypes. Furthermore, this difference between the genotype groups was maintained at age 65 and across the adult age span ( P < 0.05). No genotype-associated differences in rates of loss of grip strength or SP were found in cohort 1. These results from cohort 2 support the hypothesis that variation within a gene known to influence developing muscle affects muscle mass and muscle function in later life.
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Schöntag, Juliana M., and Maurício L. Sens. "Effective production of rapid filters with polystyrene granules as a media filter." Water Supply 15, no. 5 (June 1, 2015): 1088–98. http://dx.doi.org/10.2166/ws.2015.072.
Повний текст джерелаАнотація:
In conventional water treatment stations, the filter cleaning is performed with the use of filtered water. To save water and obtain higher production, the use of polystyrene (PS) beads has been proposed as a granular filter element because it is a granular element with a low specific mass. By being lightweight, this material requires a lower water velocity during backwash. The PS beads were applied in a descending rapid filter and compared to a conventional sand and anthracite filter, and its hydraulic performance was evaluated during the backwash with air and water interspersed. Although it presents a high fluidity, with lower rates (compared to conventional filters) of backwash, this fact does not necessarily represent an economy of backwash water, because it requires more time for cleaning. It was also observed that there is an optimal value for the removal of particles collected during the filtration without loss of material.
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Bruce, Margaret C., and Eugene N. Bruce. "Analysis of factors that influence rates of carbon monoxide uptake, distribution, and washout from blood and extravascular tissues using a multicompartment model." Journal of Applied Physiology 100, no. 4 (April 2006): 1171–80. http://dx.doi.org/10.1152/japplphysiol.00512.2005.
Повний текст джерелаАнотація:
To better understand factors that influence carbon monoxide (CO) washout rates, we utilized a multicompartment mathematical model to predict rates of CO uptake, distribution in vascular and extravascular (muscle vs. other soft tissue) compartments, and washout over a range of exposure and washout conditions with varied subject-specific parameters. We fitted this model to experimental data from 15 human subjects, for whom subject-specific parameters were known, multiple washout carboxyhemoglobin (COHb) levels were available, and CO exposure conditions were identical, to investigate the contributions of exposure conditions and individual variability to CO washout from blood. We found that CO washout from venous blood was biphasic and that postexposure times at which COHb samples were obtained significantly influenced the calculated CO half times ( P < 0.0001). The first, more rapid, phase of CO washout from the blood reflected the loss of CO to the expired air and to a slow uptake by the muscle compartment, whereas the second, slower washout phase was attributable to CO flow from the muscle compartment back to the blood and removal from blood via the expired air. When the model was used to predict the effects of varying exposure conditions for these subjects, the CO exposure duration, concentration, peak COHb levels, and subject-specific parameters each influenced washout half times. Blood volume divided by ventilation correlated better with half-time predictions than did cardiac output, muscle mass, or ventilation, but it explained only ∼50% of half-time variability. Thus exposure conditions, COHb sampling times, and individual parameters should be considered when estimating CO washout rates for poisoning victims.
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Meyer, G. A. "Mechanisms promoting recovery from defoliation in goldenrod (Solidago altissima)." Canadian Journal of Botany 76, no. 3 (March 1, 1998): 450–59. http://dx.doi.org/10.1139/b98-004.
Повний текст джерелаАнотація:
Plant responses to defoliation were examined using Solidago altissima and a leaf-chewing beetle (Trirhabda sp.). Plants were exposed to five intensities of defoliation (ranging from 0 to 85% leaf area loss) and effects on carbon gain, vegetative growth, and flowering were determined. Defoliated plants partially restored their capacity for carbon gain in the following ways: (i) activity of damaged leaves remaining after defoliation was increased via delayed senescence and enhanced photosynthetic rates and (ii) regrowth leaves on damaged plants had higher specific leaf area (leaf area per leaf mass) than comparable leaves on undamaged plants, but photosynthetic rates per unit area were equivalent to controls; thus, these leaves covered more area for a given investment in biomass with no loss in activity per unit area. Delayed leaf senescence and compensatory photosynthesis are commonly observed following defoliation, but increased specific leaf area is not generally recognized as a mechanism contributing to plant regrowth. In spite of these changes, total carbon gain capacity of defoliated plants was still less than that of controls after 3 weeks of regrowth. Overall plant performance was reduced by defoliation. Defoliated stems grew at a slower rate early in the season, added fewer new leaves in the first few weeks after defoliation, and had fewer lateral stems throughout the season. Damaged plants delayed flowering and maintained height growth later into the season than undamaged plants. Damaged stems reached heights comparable with undamaged stems by the end of the season, but they were thinner and their flower production was lower. Declines in plant growth and flowering were linear functions of the percentage leaf area loss, suggesting that even low levels of insect feeding are likely to affect plant performance.Key words: Solidago altissima, Trirhabda, defoliation, compensatory photosynthesis, insect herbivory, herbivore damage, plant compensation.
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Al-Mohaimeed, Abdulrahman A., and Abeer Abuzeid Atta Elmannan. "Experiences of Barriers and Motivators to Weight-Loss among Saudi People with Overweight or Obesity in Qassim Region - A Qualitative Study." Open Access Macedonian Journal of Medical Sciences 5, no. 7 (December 4, 2017): 1028–35. http://dx.doi.org/10.3889/oamjms.2017.171.
Повний текст джерелаАнотація:
BACKGROUND: Obesity has become a global health threat. Saudi Arabia ranks among the countries with high obesity and overweight rates. This study aims to explore experiences of Saudi people with overweight or obesity with a particular focus on the perceived barriers and motivators to weight loss.MATERIAL AND METHODS: We used a qualitative approach to recruiting a purposive sample using maximum variation sampling technique. Those who had previously attempted weight loss at least once were included in the study. In-depth interviews were conducted, transcribed and/ or audiotaped. Interviews continued until saturation was reached. The qualitative content analysis was performed.RESULTS: A total of 19 males and 18 females participated in this study with a mean Body Mass Index (BMI) of 32.6 kg/m2. Their main triggers to weight loss were concerns about overall health and the desire to improve their looks. Declining motivation, lack of family support and unhealthy eating during social gatherings were perceived as the main barriers. Motivating factors included concerns about health, family support, and availability of exercise facilities.CONCLUSION: Factors responsible for a successful weight- loss is context-specific. This study has shown several barriers as well as motivators, which play an important role in weight reduction and maintenance.