Literatura académica sobre el tema "WW 220"
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Artículos de revistas sobre el tema "WW 220"
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Min, Byeng Ryel, David Parker, Kenneth Casey, et al. "PSXI-25 The effect of plant tannins on methane and nitrous oxide emissions from dairy manure under laboratory conditions." Journal of Animal Science 98, Supplement_4 (2020): 387. http://dx.doi.org/10.1093/jas/skaa278.681.
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Abstract Emissions of greenhouse gases (GHG; methane, CH4; nitrous oxide, N2O) from dairy cattle manure contribute to global climate change. The aim of this study was to assess the associative effects of three different levels [0, 4 and 8% wet weight (WW) basis] of condensed tannins (CT; quebracho tannins) and hydrolysable tannins (HT; chestnut tannins) on CH4 and N2O emissions. The dairy manure consisted of a 50:50 volume mixture of fresh feces and dry manure scraped from the surface of an open-lot dairy in the Texas panhandle. Control (0% tannin), 4%, and 8% of CT or HT (w/w) were added to each bucket and homogenized with a hand mixer for 5 min. Aliquots of 220 g (WW) manure, with or without tannins, were placed into 1 L fermentation bottles (n = 3, total of 18 bottles) and incubated at 39o C for 14 days. A second set of 18 fermenters were set up in the same manner for sample collection at 0, 2, 3, 6, and 9 h to discern changes in pH and redox status. There were no differences in redox values with the addition of either tannin type to in vitro fermenters. However, application of CT to dairy manure reduced (P < 0.05-0.01) cumulative CH4 emissions by 68 to 63% at the concentrations of 4 and 8% WW, respectively, compared with the non-tannin control group. Both CT and HT decreased cumulative N2O emissions (P < 0.02). Examination of the emission kinetics revealed a tradeoff (interchange or pollution swapping) between CH4 and N2O emissions when tannins were applied to manure. These results suggested that the inclusion of 4% CT (WW) is a promising technique for reducing CH4 and N2O emissions from excreted dairy manure. Further study is warranted to investigate the effects of feeding CT and HT on manure-derived GHG in dairy systems.
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Marsi, Noraini, Nur Athirah Huzaisham, Anika Zafiah Muhd Rus, et al. "The Mechanical Performance of Tile Based on Plastic Waste (PW) Mixed Wood Waste (MWW)." Journal of Computational and Theoretical Nanoscience 17, no. 2 (2020): 795–802. http://dx.doi.org/10.1166/jctn.2020.8721.
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Demand for recycling product like plastics, papers, metals and alternativematerials will increase due to its numerous applications particularly on business. Recently analysis estimates that 8.3 billion metric tons of plastic has been made within the 65 years production of plastics began. Approximately 4.9 billion tons has already been terminated up in lowland or polluting the setting. This project research is to study the mechanical performance of tile based on plastic waste (PW) mixed with wood waste (WW). The objective is to evaluate the mechanical properties and to determine the optimum ratio of PW reinforced WW for tile application. In this study, there are four types of composites ratio of PW reinforced WW which are 1.0 PW:2.0 WW, 2.0 PW:2.0 WW, 3.0 PW:2.0 WW, and 4.0 PW:2.0 WW. The processes involved grinding, sizing and mixture process. Firstly, the PW and WW were grinded by using Grind Machine with the speed of 300 rpm. Then, the composition of PW and WW were mixed together with special resin by ratios into square aluminum tray with dimension of 26 cm×26 cm and thickness of 0.5 cm. The samples were cured for 48 hours at room temperature (27 °C). The maximum tensile strength was observed that the ration of 3.0 PW:2.0 WW loading produced the highest strength at 313.81 N. The bending test exhibited 2069.20 N for the ratio of 3.0 PW:2.0 WW. For impact test, 3.0 PW:2.0 WW can withstand the maximum stress at 1.67 kJ/m2. 3.0 PW:2.0 WW showed lower density of 1.070 g/cm3 and higher porosity value of 0.05%. It clearly shows that fiber matrix bonding PW:WW in distribution special resin form a strong adhesive bond at ratio of 3.0:2.0 with magnification of 10× by using Optical Microscopes Image. In conclusion, the composition ratio of PW:WW revealed that 3.0 ratio of PW reinforced with 2.0 ratio of WW produce optimum ratio for tile application.
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Craig, Aimee-Louise, Ramon Muns, Alan Gordon, and Elizabeth Magowan. "Extended nursing and/or increased starter diet allowances for low weaning weight pigs." Asian-Australasian Journal of Animal Sciences 33, no. 8 (2020): 1301–9. http://dx.doi.org/10.5713/ajas.19.0511.
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Objective: To evaluate the use of nurse sows and post-weaning nutrition strategies for low wean weight (WW) pigs on lifetime growth and efficiency.Methods: Animals (n = 270) were assigned to one of five treatments at 28 d. Low WW pigs (<6 kg) were either weaned and offered a special dietary regime recommended for low WW pigs (WEAN) or placed on a nurse sow (NURSE) and weaned at 49 d. Normal WW pigs (9 kg) (NORM) were also weaned at 28 d. After weaning, NORM and NURSE pigs were offered either a ‘high’ (4 kg/pig of starter 1 diet followed by 8 kg/pig of starter 2 diet) or ‘low’ (8 kg/pig of starter 2 diet) starter diet allowance in a 2×2 factorial arrangement. A typical grower diet was then offered, followed by a typical finisher diet until 147 d of age.Results: NORM pigs where heavier throughout their life compared to NURSE pigs (91.4 kg vs 76.2 kg at 147 d; p<0.001). WEAN pigs were heavier at 70 d compared to NURSE pigs (23.9 kg vs 21.0 kg; p<0.001), but there was no significant difference at 147 d between NURSE and WEAN treatments. NURSE pigs had reduced feed intake throughout the finishing period (1.6 kg/d; p<0.001) compared to WEAN (2.0 kg/d) and NORM (1.9 kg/d) pigs. Feed conversion ratio (FCR) of NURSE (2.20) was lower than NORM and WEAN during the finishing period (2.40 and 2.79, respectively).Conclusion: Extended (up to 49 d) nursing for low WW pigs resulted in improved FCR during the finishing period, but no overall improvement in growth rate compared to low WW pigs weaned at 28 d and offered a specialised starter regime. Normal WW pigs where significantly heavier than low WW pigs throughout the study.
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Szabó, F., Z. Lengyel, Z. Domokos, and S. Bene. "Estimation of genetic parameters and (co)variance components for weaning traits of Charolais population in Hungary." Archives Animal Breeding 50, no. 5 (2007): 447–54. http://dx.doi.org/10.5194/aab-50-447-2007.
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Abstract. Weaning performance of 10 808 purebred offsprings (4991 male and 5817 female) of 80 sires in 13 farms were analised using animal model. Heritability, breeding value, (co)variance components for weaning weight (WW), preweaning daily gain (PDG), 205-day weight (CWW) were calculated. Farm, parity, year of birth, season of birth, sex were treated as fixed, and the maternal permanent environment was treated as random effects. In case of WW and PDG, the age of the calves at weaning was fitted as a covariant. Data were analyzed with MTDFREML (Boldman et al. 1993) program. The overall mean value and standard deviation of WW, PDG and CWW were 221±47 kg, 1,111±0.21 kg/day and 226±42 kg, respectively. The age of the calves at weaning was 202 days. The direct heritability (h2d) of WW and PDG were 0.57±0.08, 0.49±0.07 and CWW was 0.44±0.06, respectively. The maternal heritability (h2m) of these traits were 0.32±0.09, 0.33±0.10 and 0.33±0.09, respectively. The direct-maternal correlations (rdm) were strong and negative. The medium heritability estimates for direct effects suggest that progeny tests should be used in this population to increase genetic improvement.
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Khaki, Ali Raza, Yuan Xu, Shasank R. Chennupati, et al. "Intensity of End of Life Care for Hematologic Malignancy Patients in Western Washington, United States and Alberta, Canada." Blood 136, Supplement 1 (2020): 21. http://dx.doi.org/10.1182/blood-2020-134825.
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Background: Aggressive care at the end of life (EOL) leads to unnecessary suffering and healthcare costs for patients with cancer. We have previously shown that among patients with solid tumor malignancies, EOL utilization of chemotherapy, intensive care unit (ICU) admissions and >1 emergency department (ED) visits are higher in Washington State vs Alberta (AB). In this study, we use cancer registry and claims data to compare EOL care among patients with hematological malignancies between western Washington (WW) and AB. Methods: Adult patients with hematological malignancies diagnosed between 2007 and 2017 who died before December 31, 2018 were identified from regional population-based cancer registries in WW and AB. Data sources were 1) WW Cancer Surveillance System (a regional SEER registry) with data from 13 counties linked to enrollment files and claims from four regional insurers and 2) Canada National Ambulatory Care Reporting System, Discharge Abstracts Database, and chemotherapy records from AB Health Services. Proportions of patients receiving chemotherapy, ICU admission, or >1 ED visit in the last 30 days of life (DOL) in WW and AB were determined among all patients and those ≥65 years and compared using two sample z-test with two-tailed hypothesis (α=0.006 after Bonferroni correction). Results: 7859 AB and 3767 WW patients met study inclusion criteria. Median age was 76 (IQR 66-83) and 79 (IQR 71-86) for AB and WW, respectively; 78% and 85% were over age 65, 33% and 59% with ≥2 Charlson Comorbidity Score. Cancer distribution was 33% (AB) and 54% (WW) non-Hodgkin lymphoma, 14% (AB) and 20% (WW) myeloma and 27% (AB) and 19% (AB) leukemia. Table 1 shows utilization of chemotherapy, >1 ED visits and ICU admissions in AB and WW for all patients and Table 2 in those ≥65 years. More patients in WW vs AB were treated with chemotherapy (21% WW vs 7% AB) and admitted to ICU (34% WW vs 9% AB) in the last 30 DOL, whereas multiple ED visits were more similar between WW and AB (17% vs 19%, respectively). Similarly, among patients ≥65 years, chemotherapy use and ICU admissions were higher in WW. The same was true for patients in the last 60 and 90 DOL. Conclusions: Similar to what was noted in solid tumor patients, intensity of healthcare use at EOL is greater in WW vs AB for patients with hematological malignancies. However, ≥1 ED visits were similar between populations. Further work is needed to understand drivers of high intensity healthcare use and identify interventions to minimize low value care at EOL. Disclosures Khaki: Merck: Other: share/stockholder; Pfizer: Other: share/stockholder. Ramsey:AstraZeneca: Other: Personal Fees. Cowan:Janssen: Consultancy, Research Funding; Abbvie: Research Funding; Cellectar: Consultancy; Sanofi: Consultancy; Bristol Myers Squibb: Research Funding.
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Suhada, Hary, Sumadi (Sumadi), and Nono Ngadiyono. "Estimasi Parameter Genetik Sifat Produksi Sapi Simmental di Balai Pembibitan Ternak Unggul Sapi Potong Padang Mengatas, Sumatera Barat (Estimation of Genetic Parameters of Production Characteristics on Simmental Cattle at Balai Pembibitan Ternak Unggulan." Buletin Peternakan 33, no. 1 (2012): 1. http://dx.doi.org/10.21059/buletinpeternak.v33i1.127.
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<p>The objectives of this research were to estimate the genetic parameters of production characteristics, breeding value (BV), weaning weight ratio (WWR) correlation with BV and most probable producing ability (MPPA) of Simmental cattle reared at Balai Pembibitan Ternak Unggul Sapi Potong Padang Mengatas. Research was based on records of birth weight (BW), weaning weight (WW), post weaning average daily gain (ADG) and yearling weight (YW) from 2002 to 2007. Heritability value (h2) was estimated for BV, WW, ADG and YW using paternal-half sib correlation and repeatability value (r) of characteristics of both using intra class correlation. The genetic correlation (rG) of BW-WW, WW-YW, WW-ADG, WW-YW, WW-ADG and YW-ADG were analyzed by variance and covariance. BV and MPPA estimation was base on record of weaning weight. The h2 value of BW, WW, YW and ADG were 0.11±0.09; 0.39±0.16; 0.43±0.19; and 0.46±0.20, respectively. The r of BW, WW, YW and ADG, were 0.25±0.16; 0.32±0.18; 0.25±0.22; and 0.34±0.16, respectively. The genetic correlation value of BW-WW, WW-YW, WW-ADG, WW-YW, WW-ADG and YW-ADG were 0.29±0.37; 0.46±0.33; 0.2 ±0.39; 0.68±0.16; 0.006±0.30 and 0.57±0.21, respectively. From 18 Bulls, 10 bulls (55.56%) had the BV higher then average population value, 142.21 kg and the remaining 8 bulls (44.44%) was lower then average population value. Frequency of the BV of prospective male and female with WW higher than WW average was 210 calves (44.68%); whereas, 260 calves (55.32%) had WW lower than average population corrected with parent age (130.21 kg). Range of absolute BV was from 112.77 kg to 155.91 kg. The BV of male had average frequency higher than that of female, i.e. 149 males (66.22%) compared to 61 female (24.90%). The MPPA with above the average WW of the population was 150 cows (41.67%) and the rest of cows (210 head or 58.33%) were under the<br />average. The WWR had positive and significant correlation (1.00**) with the NP. It means that, if the cattle have a high WWR, they will also have a high NP, so that they can be used as the criteria of selection.</p><p>(Key words: Simmental cattle, Genetic parameters, Breeding value, Most probable producing ability, Weaning weight ratio)<br /><br /></p>
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Miller, Jacob A., Hannah Wang, Daniel T. Chang, and Erqi L. Pollom. "Cost-Effectiveness and Quality-Adjusted Survival of Watch and Wait After Complete Response to Chemoradiotherapy for Rectal Cancer." JNCI: Journal of the National Cancer Institute 112, no. 8 (2020): 792–801. http://dx.doi.org/10.1093/jnci/djaa003.
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Abstract Background Neoadjuvant chemoradiotherapy (CRT) followed by total mesorectal excision (TME) is the standard treatment for locally advanced rectal cancer. There is interest in deescalating local therapy after a clinical complete response to CRT. We hypothesized that a watch-and-wait (WW) strategy offers comparable cancer-specific survival, superior quality-adjusted survival, and reduced cost compared with upfront TME. Methods We developed a decision-analytic model to compare WW, low anterior resection, and abdominoperineal resection for patients achieving a clinical complete response to CRT. Rates of local regrowth, pelvic recurrence, and distant metastasis were derived from series comparing WW with TME after pathologic complete response. Lifetime incremental costs and quality-adjusted life-years (QALY) were calculated between strategies, and sensitivity analyses were performed to study model uncertainty. Results The base case 5-year cancer-specific survival was 93.5% (95% confidence interval [CI] = 91.5% to 94.9%) on a WW program compared with 95.9% (95% CI = 93.6% to 97.4%) after upfront TME. WW was dominant relative to low anterior resection, with cost savings of $28 500 (95% CI = $22 200 to $39 000) and incremental QALY of 0.527 (95% CI = 0.138 to 1.125). WW was also dominant relative to abdominoperineal resection, with a cost savings of $32 100 (95% CI = $21 800 to $49 200) and incremental QALY of 0.601 (95% CI = 0.213 to 1.208). WW remained dominant in sensitivity analysis unless the rate of surgical salvage fell to 73.0%. Conclusions Using current multi-institutional recurrence estimates, we observed comparable cancer-specific survival, superior quality-adjusted survival, and decreased costs with WW compared with upfront TME. Upfront TME was preferred when surgical salvage rates were low.
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Yang, Gai-Xiu, Yong-Ming Sun, Xiao-Ying Kong, et al. "Factors affecting the performance of a single-chamber microbial fuel cell-type biological oxygen demand sensor." Water Science and Technology 68, no. 9 (2013): 1914–19. http://dx.doi.org/10.2166/wst.2013.415.
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Microbial fuel cells (MFCs) are devices that exploit microorganisms as biocatalysts to degrade organic matter or sludge present in wastewater (WW), and thereby generate electricity. We developed a simple, low-cost single-chamber microbial fuel cell (SCMFC)-type biochemical oxygen demand (BOD) sensor using carbon felt (anode) and activated sludge, and demonstrated its feasibility in the construction of a real-time BOD measurement system. Further, the effects of anodic pH and organic concentration on SCMFC performance were examined, and the correlation between BOD concentration and its response time was analyzed. Our results demonstrated that the SCMFC exhibited a stable voltage after 132 min following the addition of synthetic WW (BOD concentration: 200 mg/L). Notably, the response signal increased with an increase in BOD concentration (range: 5–200 mg/L) and was found to be directly proportional to the substrate concentration. However, at higher BOD concentrations (>120 mg/L) the response signal remained unaltered. Furthermore, we optimized the SCMFC using synthetic WW, and tested it with real WW. Upon feeding real WW, the BOD values exhibited a standard deviation from 2.08 to 8.3% when compared to the standard BOD5 method, thus demonstrating the practical applicability of the developed system to real treatment effluents.
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Chen, Yu Yun, and Sheng Ke Yang. "Levels of Toxic Elements in Fish from Fishing Ground Using Geothermal Water in Guanzhong Basin, China." Advanced Materials Research 573-574 (October 2012): 654–58. http://dx.doi.org/10.4028/www.scientific.net/amr.573-574.654.
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Levels of toxic elements in fish from fishing ground using geothermal water in Guanzhong Basin, China were investigated. Six elements including elements cadmium (Cd), arsenic (As), copper (Cu), fluorine (F), lead (Pb) and chromium (Cr) in fish were emphatically assessed because they were limited by safety requirements for non-environmental pollution aquatic products (GB/T18407.4-2001). Element F, Cr，Cu，As，Cd and Pb concentrations in fish muscle were in the range of 4.3-18.2 mg/kg wet weight (ww), 0.21-1.53 mg/kg ww, 2.34-2.92 mg/kg ww, nd-0.08 mg/kg ww, 0.01-0.13 mg/kg ww and 0.05-1.99 mg/kg ww, respectively. Element F concentration in each fish muscle was higher than its tolerance limit (2.0 mg/kg ww). Element Cd concentration in Tilapia muscle from Beida fishing ground exceeded its limit value (0.1 mg/kg ww). Tilapia muscle from Tezhong and Beida fishing grounds and Ctenopharyngodon idella muscle from Heyang and Changda fishing ground contained more than the safe limit of Pb (0.5 mg/kg).The bioconcentration factor (BCF) of 6 elements for fish muscle of ctenopharyngodon idella from Heyang and Changda fishing grounds were calculated. The results suggested that using geothermal heat for fish breeding may lower BCF of F and Cr but enhance bioaccumulation of Cu, As, Cd and Pb in fish muscle, which may increase health risk.
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McManus, Concepta Margaret, Edgard Franco Gomes, Tiago Prado Paim, et al. "Effect of supplementary milk feeding on growth and survival of Santa Inês lambs." Ciência Animal Brasileira 15, no. 4 (2014): 451–57. http://dx.doi.org/10.1590/1089-6891v15i48725.
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The objective of this experiment was to evaluate the effect of alternative methods of feeding on the performance and mortality rate of suckling lambs. Eighty-four Santa Inês lambs, twins and singles, half male and half female, were used. The animals were divided into three groups: A (control), B (bovine milk) and C (bovine milk plus Multi-mixture). The experiment began when lambs were three weeks old and finished at weaning at 2 months of age. Each animal from group B received 200 mL of bovine milk daily; group C received 200 mL of bovine milk plus 20g of Multi-mixture daily. Weaning Weight (WW) was 10.90, 13.20 and 13.59 kg, respectively for groups A, B and C. Daily Weight Gain (DWG) was 126, 163 and 168 g.day-1 respectively. The mortality rate was higher (p<0.05) in group A than in group B and C. Gender influenced significantly (p<0.05) the DWG and WW. DWG and WW were lower for the animals that died compared to the animals that survived: 7.94 kg against 13.51 kg (WW) and 77 g against 165 g (DWG) respectively. The twins had lower (P<0.05) WW and DWG when compared to the singles. The use of milk-replacers with or without Multi-mixture is effective and it can increase the productivity of the system.
Tesis sobre el tema "WW 220"
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Gauthier, Anne-Sophie. "Contribution à l'amélioration de la conservation cornéenne en bioréacteur." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCE011.
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Depuis l’abandon depuis les années 70-80, pour des raisons logistiques et de sécurité sanitaire, des greffes fraiches dont la longévité dépassait deux décennies, la greffe s’est organisée autour de deux techniques d’eye banking: hypothermie aux USA et organoculture en Europe (dont Besançon fut pionnière pour la France) permettant une conservation respectivement à court et moyen terme. L’œdème stromal inéluctable lié à ces techniques passives engendre une perte endothéliale importante qui réduit la longévité des greffons, limite les contrôles qualités de plus en plus exigeants et obère les développements futurs tels les prédécoupes des greffons ou le bioingéniéring endothélial.Le laboratoire « Biologie, imagerie et ingéniérie de la Greffe de Cornée (BiiGC, EA 2521, Université Jean Monnet de St-Etienne) a développé une technologie de conservation active en bioréacteur qui limite l’œdème cornéen en restituant le gradient de pression de part et d’autre de la cornée et la circulation de milieu nutritif. Il permet ainsi de pallier à ces deux inconvenients majeurs et de mettre en œuvre les développements du futur.Notre travail de thèse 1/ retrace les évolutions des techniques de conservation et de contrôle des greffons ; 2/ dresse le bilan de l’évolution des techniques/indications de greffes en France; 3/ documente la perte cellulaire endothéliale précoce liée à la conservation passive en organoculture ; 4/ la compare avec la technologie active de conservation en bioréacteur.Mots clés : conservation cornéenne, banque de cornée, viabilité endothéliale, organoculture, bioréacteur, survie des greffonsSince the abandonment for logistical and health security reasons in the 70s-80 of fresh grafts whose longevity exceeded two decades, the technical storage was organized around two techniques of eye banking: hypothermia (short term storage) in the USA and organ culture (long term storage) in Europe. Besançon was a pioneer in France for this technique. Induced stromal edema associated with these passive techniques leads to a significant endothelial cell loss and reduces grafts survival, limits quality control and obstructs further developments such as pre-cut endothelial graft or endothelial bioengineering.The laboratory "Biology, Imaging and Engineering of the Corneal Graft (BiiGC, EA 2521, Jean Monnet University of St-Etienne) has developed an active storage system, the bioreactor, that limits corneal edema by restoring a pressure corneal gradient and circulation of the storage medium. Bioreactor makes possible to overcome these two major disadvantages and to implement the developments of the future.The aim of this thesis is to 1 / trace the evolution of storage and control techniques of corneal graft; 2 / review the evolution of corneal graft techniques / indications in France; 3 / document early endothelial cell loss related to passive conservation in organ culture; 4 / Compare organ culture versus bioreactor storage.Key words: corneal storage, eye bank, endothelial viability, organ culture, bioreactor, graft survival
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Tellgmann, Gabriele. "Messung der Reaktionsenthalpie von Teilreaktionen der visuellen Kaskade." Doctoral thesis, [S.l. : s.n.], 1998. http://deposit.ddb.de/cgi-bin/dokserv?idn=956128963.
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Gajera, Chandresh Ravjibhai. "LRP2 promotes adult neurogenesis through suppression of BMP signaling in the subventricular zone." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16125.
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LRP2/Megalin ist ein Rezeptor der LDL-Rezeptor Genfamilie mit essentieller Funktion in der Entwicklung des Zentralnervensystems. Der Rezeptor wird im Neuroepithel des Embryos exprimiert und steuert die Ausbildung der Vorderhirnstrukturen. In weiteren Untersuchungen an LRP2-defizienten Mäusen konnte ich zeigen, dass der Verlust der Expression des Rezeptors in adulten Tieren zu einer Beeinträchtigung der Proliferation neuronaler Vorläuferzellen in der subventrikulären Zone (SVZ) des lateralen Ventrikels führt. Infolgedessen war die Anzahl der Neuroblasten reduziert, die zum olfaktorischen Bulbus wandern und dort zu Interneuronen differenzieren. Anhand immunhistologischer Untersuchungen konnte ich nachweisen, dass der Verlust von LRP2 zu einer verminderten Anzahl GFAP-positiver Zellen, die auch die neuronalen Stammzellen (Typ B Zellen) umfassen, führt. Weiterhin wiesen LRP2 Mutanten eine Reduktion in den Signalen für Nestin, DLX2, PSA-NCAM und DCX. Meine derzeitige Hypothese besagt daher, dass LRP2 ebenso wie im embryonalen Neuroepithel auch in der adulten neuronalen Stammzellnische eine Rolle bei der Regulation der BMP4 Signalwege spielt. Dies wird möglicherweise durch Endozytose-vermittelte Aufnahme mit anschließendem Abbau des Morphogens durch LRP2 vermittelt, wie es bereits in vitro gezeigt werden konnte. BMP4 hat im Wesentlichen eine anti-proliferative Wirkung. Eine exakt gesteuerte Regulation der Konzentration dieses Morphogens ist daher eine Vorraussetzung für ein Neurogenese-permissives Milieu in der adulten neurogenen Stammzellnische. Die Ergebnisse meiner Arbeit entschlüsseln eine neue Rolle von LRP2 in der adulten Neurogenese. Die Expression des Rezeptors im Ependym des lateralen Ventrikels ist essentiell für die Regulation der BMP Signalwege in der neurogenen Stammzellnische.LRP2 (also know as megalin) is a member of the low-density lipoprotein receptor gene family that plays an important role in regulation of neurogenesis in the embryonic neural tube. During early forebrain development, LRP2 deficiency leads to an increase in bone morphogenetic protein 4 (Bmp4) expression and signalling in the dorsal neuroepithelium, and a loss of sonic hedgehog (Shh) expression in the ventral forebrain. In this thesis I demonstrate that LRP2 is expressed in ependymal cells of the lateral ventricles in the adult brain. Intriguingly, expression is restricted to the ependyma that faces the stem cell niche. Expression is not seen in ependyma elsewhere in the lateral ventricles or in the dentate gyrus, the second neurogenic zone of the adult mouse brain. I further show that lack of LRP2 expression in adult mice results in impaired proliferation of neural precursor cells in the SVZ resulting in a decreased number of neuroblasts reaching the olfactory bulb. Using immunohistological detection of marker proteins, absence of LRP2 was shown mainly to affect the GFAP-positive neuronal precursor cell population in the SVZ (B cells). Furthermore, Lrp2 mutant mice also showed a decrease in the signals for nestin, DLX2, PSA-NCAM and DCX. Reduced neurogenesis in the SVZ in LRP2-deficient mice coincides with a significant increase in BMP2/4 expression and enhanced activation of downstream mediators Phospho-SMAD1/5/8 and ID3 in the stem cell niche. My findings revealed a novel regulatory pathway whereby LRP2 down-regulates BMP signaling to modulate the instructive microenvironment of the SVZ and to enable adult neurogenesis to proceed. Thus, LRP2 plays a crucial role in regulating BMP-signaling levels in the adult SVZ, highlighting the unique role of ependymal cells in this stem cell niche. The underlying mechanism of LRP2 action in control of neurogenesis may thus be conserved between the embryonic and adult brain.
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Puente, Eugenia Rojas. "Turnover and localization of the actin-binding protein Drebrin in neurons." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17587.
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Die vorliegende Arbeit erforscht die Regulation der Expression von Drebrin; DBN (Developmentally Regulated Brain Protein) in Neuronen. DBN ist ein Protein das Actin bindet und Actin-Filamente bündeln kann. Änderungen der Morphologie der Spines verändern die synaptische Aktivität und Plastizität – wichtigen Prozessen bei der Gedächtnisbildung und Alterung des Gehirns, sowie bei geistigen Störungen bzw. Behinderungen. DBN-Expression im Alter und in einigen neurodegenerativen Krankheiten reduziert ist. Eine schwächere Expression von DBN in Spines geht außerdem mit einem Verlust an synaptischen Verbindungen einher, einem gemeinsamen Merkmal von Alterung und neurologischen Störungen wie der Alzheimer Krankheit. Diese Befunde bildeten die Motivation und Grundlage für meine Erforschung der Produktion und Lokalisierung von DBN. In meinem Projekt, habe ich den Effekt der sequenzspezifischen S647-Phosphorylierung von DBN untersucht. Die Arbeit zeigt, dass diese post-translatorische Modifikation die Stabilität von DBN reguliert. Ich habe FUNCAT-PLA und Puro-PLA für die Visualisierung von de novo synthetisierten Proteinen in situ benutzt. Mittels hochauflösender Fluoreszenz-Hybridisierung konnte ich zeigen, dass DBN nicht nur im Zellkörper sondern auch lokal in den Spines translatiert wird. Meine Resultate bieten eine Grundlage für das Verständnis der Regulierung de DBN-Konzentration in Zellen und ermöglichen die weitere Erforschung der Rolle der S647-Phosphorylierung von DBN für die Morphologie von Spines. Die Arbeit bildet außerdem eine experimentelle Plattform für weitere Studien der Rolle von DBN für Spines, sowohl in Bezug auf Stabilität als auch der synaptischen Funktion und Stabilität.This thesis studies the abundance of the protein Drebrin; DBN (Developmentally Regulated Brain Protein) in neurons, which is an actin-binding protein capable of bundling actin filaments. Synapses in the mammalian brain are formed on tiny protrusions, called dendritic spines. Changes in spine morphology affect synaptic activity and plasticity, which are processes underlying memory formation. DBN abundance plays an important role in regulating dendritic spine morphology. Cognitive decline and neurodegenerative conditions have been shown to be linked with a decrease in DBN levels. A weakening in the expression of this protein in spines is associated with the loss of synaptic connections, a common feature of ageing and neurological disorders such as Alzheimer''s disease. This evidence was the underlying motivation for studying the localization and turnover of DBN. I studied the effect of the site-specific S647 phosphorylation of DBN and found that such post-translational modification regulates protein stability. For the project, I established several novel techniques in our laboratory, including state-of-the-art methods such as FUNCAT-PLA and Puro-PLA for the visualization of de novo synthesized proteins in situ. My results show that DBN translation occurs not only in somata but also locally in the dendrites and spines. The same observation is true for DBN transcripts, which are present both in the soma and dendrites of neurons. These observations suggest that DBN could play an important role during synaptic plasticity. My results allow the future investigation of the potential role of site-specific phosphorylation of DBN in spine morphology. This PhD thesis represents a contribution to better understanding the regulation of DBN abundance. It also provides an experimental platform for additional investigation about the role of DBN in spine morphology, regarding its stability and its correlation with synaptic maintenance and function.
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Sanguinetti, Scheck Juan Ignacio. "Neural bases of navigation in foraging and play." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19974.
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Für die meisten Säugetiere ist Navigation eine essentielle kognitive Fähigkeit. Im Bereich der Neurowissenschaften gab es immense Fortschritte im Verständnis neuronaler Grundlagen von Navigation. Diese Dissertation beschäftigt sich mit der neuronalen Grundlage von Navigation im Hinblick auf Hirnstruktur (d.h. Parasubikulum) und ethologisch relevante Verhaltensweisen (d.h. Heimkehr und Spielverhalten).
Im ersten Kapitel konzentriere ich mich auf das Verhältnis von Struktur und Funktion im Parasubikulum. Wir postulieren, dass das Parasubikulum durch seine selektive Vernetzung mit dem entorhinalen Kortex, durch seine starke interne Konnektivität, sowie wegen dem hohen Grad räumlich selektiver Aktivitätsmuster seiner Neurone im Bezug auf die Kontrolle von Gitterzellaktivität und räumlicher Navigation eine herausragende Stellung einnimmt.
Im zweiten Kapitel untersuche ich die neuronale Grundlage von Heimkehr. Wir nutzen die starke Verbundenheit von Laborratten zu ihrem Zuhause. Wir zeigen, dass das Parasubikulum und der entorhinale Kortex keinen expliziten Heimvektor besitzen und dass die Präsenz des Zuhauses keine globale Veränderung der neuralen Repräsentation des Raums hervorruft. Allerdings führte die Präsenz des Zuhauses oder anderer geometrischer Objekte zu einer Verzerrung von Gitterzellen.
Im dritten Kapitel unteruche ich Navigation im Hinblick auf Spielverhalten. Ratten erlernen das Versteckspiel schnell und verhalten sich erstaunlich regelkonform. Zeigen Ratten spielspezifische Vokalisationen. Gleichzeitige Ableitungen neuronaler Aktivität im medialen präfrontalen Kortex offenbarten starke und spezifische Antworten der meisten Nervenzellen auf verschiedene Phasen des Spiels des spezifischen Spielkontextes wiederspiegeln.
Diese Arbeit liefert durch ihren ethologischen Ansatz und durch Verhaltensanalysen von sich frei verhaltenden Tieren einen wichtigen Beitrag zum besseren Verständnis neuronaler Grundlagen von Navigation im Säugetiergehirn.Navigation is an essential cognitive skill in the life of most animals. Animals move along space to procure the advantages of different places in the environment, and to adapt to ever changing resources, dangers and needs. This thesis addresses the neural bases of navigation in the context of brain structure (i.e. the parasubiculum) and ethologically relevant behaviors (i.e. homing and playing). In the first chapter I focus on the structure function relation of the parasubiculum: an understudied area of the rat’s parahippocampal cortex. We performed the most comprehensive study of the parasubiculum up to date and propose that, because of its selective connectivity with the medial entorhinal cortex, its internal connectivity, and the high spatial and head directional tuning of its neurons, the parasubiculum sits in remarkable position to control grid cell activity and navigation. In the second chapter, I study the neural bases of homing. We use the lab-rat' s strong attachment to its home cage to study whether brains maintain an online home vector. We show, that the parasubiculum and medial entorhinal cortex do not have an explicit home vector representation, and that the presence of home did not affect global encoding of space. However, we do find that grid cells are distorted by the home or other geometrical features affecting the internal environment. In the third chapter, I study navigation in an interspecies role-playing game. We played 'Hide and Seek' with rats and found that they acquired the game easily and played by the rules. Rats were strategic and developed game specific vocalizations patterns. We recorded from the medial prefrontal cortex and found that neurons respond sharply to different phases of the game, and may encode as well the context in which this events take place. By emphasizing ethological approaches and free behaviors this thesis contributes to an increased understanding of the neural underpinnings of navigation in the mammalian brain.
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Schrötter, Sandra. "Specificity of developmental- and growth factor-dependent phosphorylation of Akt isoforms in neurons." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17593.
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Ein Signalweg während der neuronalen Entwicklung im adulten Gehirn ist der PI3K-PTEN-Akt Signalweg. Akt ist eine Kinase die drei verschiedene Isoformen besitzt, welche durch die Phosphorylierung von S473 und T308 aktiviert werden. KO Modelle der Isoformen haben gezeigt, dass nicht alle Funktionen von anderen Isoformen kompensiert werden können. Die genaue Rolle der einzelnen Isoformen in einem neuronalen Zusammenhang ist nur wenig untersucht. Ziel dieser Arbeit war, eine detaillierte Analyse der einzelnen Akt Isoformen nach der Aktivierung des PI3K-PTEN Signalweges. Dazu wurde im Labor eine neue Methode zur isoelektrischen Fokussierung etabliert., welche Proteine nach ihrer Ladung trennt und somit eine Analyse der Dynamik von Akt Phosphorylierungen in neuronalen Zellen erlaubt. Im Zuge dieser Arbeit konnten wir bisher unerkannte Merkmale der Akt Aktivierung und Phosphorylierung identifizieren. Wir konnten zeigen, dass die S473 und T308 Phosphorylierung in Neuroblastomazellen unabhängig voneinander auftreten kann und, dass verschiedene Akt1 Moleküle unterschiedlich auf die Inhibition von PI3K reagieren. Außerdem konnten wir Verschiebungen in der Aktivierung und in der Expression der unterschiedlichen Isoformen während der postnatalen Gehirnentwicklung der Ratte feststellen. Des Weiteren konnten wir zeigen, dass die Aktivierung von Akt von dem Signal und dem Alter der Neurone abhängig ist. Noch nicht vollständig differenzierte Neurone reagieren vor allem auf BDNF Stimulation, wohingegen adulte, differenzierte Neurone hauptsächlich auf EGF reagieren und dort explizit Akt2 über EGFR und PI3K-p110α Signale aktiviert wird. Im Gegensatz dazu führt der Verlust von PTEN zu einer Aktivierung von hauptsächlich Akt1. Zusammenfassend zeigt diese Arbeit einen komplexen Zusammenhang der Phosphorylierung von Akt auf, welcher Signal- und Entwicklungsabhängig ist bei dem unterschiedliche Akt Populationen auf Wachstumsfaktoren und auf PTEN Verlust reagieren.A major pathway involved in neuronal development is the PI3K-PTEN-Akt pathway. Akt comprises three isoforms, which are activated by phosphorylation of the residues S473 and T308. KO animals for the isoforms have shown differential as well as redundant functions of the three isoforms. However, their individual role in neuronal signaling pathways has not yet been studied in great detail. The aim of this study was to obtain further insight into differential Akt isoform signaling in response to changes in the activity of PI3K and PTEN pathway. A new isoelectric focusing method was established, which allowed us to separate Akt proteins according to their charge, therefore, providing a refined read-out to study dynamics of Akt phosphorylation in a neuronal background. In the course of this project we were able to identify previously undescribed features of Akt phosphorylation and activation. First, we could provide evidence for an uncoupling of the two activating phosphorylation events at S473 and T308 in neuroblastoma cells and differential sensitivities of Akt1 forms towards PI3K inhibition. Secondly, we found a transient shift in Akt isoform activation and abundance during postnatal rat brain development. Thirdly, we were able to show that the activation of different Akt isoforms is dependent of the upstream signal as well as the age of the neuron. Immature neurons were found to be highly responsive to BDNF treatment, whereas mature neurons were most responsive to EGF stimulation leading exclusively to activation of Akt2 in an EGFR- and PI3K/p110α-dependent manner. Stimulation of Akt phosphorylation by the loss of PTEN led to an activation of mainly Akt1 forms, which suggests inherent differences in the Akt pools that are accessible to growth factors dependent PI3Ks as compared to the pools that are controlled by PTEN. In summary, this thesis demonstrates the presence of complex phosphorylation events of Akt in a developmental- and signal-dependent manner in neurons.
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Frohnecke, Nora. "Funktionelle Charakterisierung des Ferredoxin Redoxsystems von Toxoplasma gondii." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19075.
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Toxoplasmose ist weltweit eine der am häufigsten auftretenden parasitären Zoonosen mit einer geschätzten Infektionsrate von über 30%. Toxoplasma gondii (Phylum: Apicomplexa) besitzt ein Plastid ähnliches Organell, den Apicoplasten. In diesem befindet sich das einzig bekannte Redoxsystem, welches aus der Ferredoxin-NADP+-Reduktase und Ferredoxin (Fd) besteht. Fd als Elektonendonator liefert Elektronen an verschiedene essentielle Stoffwechselwege, wie der Isoprenoidvorstufen- und Liponsäuresynthese. Um die bei einem Elektronentransfer benötigte direkte Protein-Protein-Interaktion eingehend zu analysieren, wurde ein bakterielles Reverse Two Hybrid System verwendet, womit die Interaktion von TgFd und TgLipA gezeigt werden konnte. Da angenommen wird, dass Fd eine zentrale Rolle in verschiedenen Stoffwechselwegen übernimmt, ist für einen Fd Knockout ein komplexer biochemischer Phänotyp zu erwarten, der möglicherweise zum Absterben der Parasiten führt. Zur Untersuchung dessen wurden zwei komplementäre Wege verfolgt. Eine der Strategien basierte auf dem grundsätzlichen Nachweis, dass Fd unerlässlich für das Überleben von T. gondii ist. Mit Hilfe des DiCre Systems sollte ein definierter genetischer Fd Knockout hergestellt werden, welcher jedoch nicht zweifelsfrei generiert werden konnte. Bei der zweiten Strategie kam ein konditionales Knockdown System zur Anwendung, bei welchem die Expression des Fd Gens nach Induktion herabreguliert wird. Mit Hilfe dessen konnten weitreichende Auswirkungen der Fd Defizienz auf T. gondii gezeigt werden: die Fettsäuresynthese der im Apicoplasten synthetisierten Fettsäuren ist reduziert sowie die Motilität durch eine beeinträchtigte Isoprenoidsynthese verringert, wodurch insgesamt drastische Auswirkungen auf das Parasitenwachstum gezeigt werden konnten. Beide Stoffwechsel sind vom Elektronendonator Fd abhängig und durch die Fd Herabregulation betroffen. Die Ergebnisse unterstreichen die essentielle Rolle des Fd-Redoxsystems von T. gondii.Toxoplasmosis is one of the most common parasitic zoonoses world-wide, around 30% of human beings are infected. Toxoplasma gondii (phylum: Apicomplexa) contains a unique intracellular organelle derived from plastids, called apicoplast. The only known redox system in the apicoplast consists of the ferredoxin NADP+-reductase and its redox partner, ferredoxin (Fd). The latter donates electrons to different essential metabolic pathways in the apicoplast like the last two enzymes of the isoprenoid precursor biosynthesis and the lipoic acid synthesis. To dissect protein protein interactions for an electron transfer a bacterial reverse two hybrid system was used. The physical interaction of both proteins TgFd and TgLipA could be shown. Fd is supposed to play an important role in diverse metabolic pathways, hence a knock-out of the Fd gene is expected to generate a complex biochemical phenotype and be lethal to the parasite. Therefore two complementary approaches were used to analyze the role of TgFd in this context. The first strategy shall verify the essentiality of TgFd for the survival of T. gondii. It is based on the DiCre system whereby a defined genetic knock out of TgFd is produced. Respectives parasites have been generated, but at the end no genetic Fd knock out could be produced. In the second approach a conditional knock-down was generated, where the expression of the TgFd gene is repressed after induction. The Fd deficiency has wide ranging effects on T. gondii: The fatty acid synthesis of the apicoplast-synthesized fatty acids is reduced as well as the motility is decreased due to an affected isoprenoid synthesis. In total this leads to a dramatic inhibition of parasite growth. Both metabolic pathways depend upon the electron carrier Fd and thus are affected by Fd deficiency. The results underline the essential role of the ferredoxin redoxsystem of T. gondii.
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Kaufmann, Joel Christoph David. "FTIR spectroscopic study on the photocycle mechanism of Channelrhodopsins." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/20933.
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Kanalrhodopsine (ChRs) sind lichtgesteuerte Ionenkanäle aus einzelligen Grünalgen, die in der Optogenetik verwendet werden. Photonabsorption führt zur Isomerisierung des Retinal-Kofaktors, was eine Reihe von Reaktionen auslöst, die als Photozyklus bezeichnet werden und die Bildung des leitenden Zustands umfassen. In dieser Arbeit wurde der Photozyklus-Mechanismus ausgewählter ChRs mittels FTIR (Fourier Transform Infrarot)- und UV-Vis-Spektroskopie, sowie Retinalextraktion und HPLC (Hochleistungsflüssigkeitschromatographie)-Analyse untersucht.
Photorezeptoren sind dafür optimiert, Lichtenergie zu nutzen, um Konformationsänderungen des Proteins hervorzurufen. Dafür wird ein Teil der Lichtenergie durch eine transiente Verdrillung des Chromophors gespeichert. In dieser Arbeit wird gezeigt, dass der Transfer der gespeicherten Energie zum Protein in ReaChR stark vom Protonierungszustand von Glu163 beeinflusst wird; er wird durch eine erhöhte Rigidität des aktiven Zentrums bei protoniertem Glu163 verlangsamt. In Chrimson hingegen relaxiert der Chromophor nach Photoisomerisierung, was auf einen verdrillten Chromophor im Dunkelzustand hinweist, was vermutlich für die bathochrome Verschiebung von Bedeutung ist.
Zusätzlich zur Chromophorgeometrie beeinflusst der Protonierungszustand von Glu163 in ReaChR und dem homologen Glu165 in Chrimson die Stereoselektivität der Photoreaktion. Ein weiterer Faktor der Stereoselektivität ist Asp196 in ReaChR (Asp195 in C1C2), welches im Photozyklus deprotoniert.
Die Bildung des leitenden Zustands in C1C2 und ReaChR geht mit einem Wassereinstrom ins Protein einher, welcher den Transport größerer Kationen erleichtert. Die Deprotonierung von Glu130 in ReaChR (Glu129 in C1C2) verändert die Ionenselektivität des Kanals, wie aus elektrophysiologischen Messungen bekannt ist. In Chrimson ist das Ausmaß des Wassereinstroms deutlich reduziert, was – in Übereinstimmung mit elektrophysiologischen Experimenten – den Transport von Protonen begünstigt.Channelrhodopsins (ChRs) are light-gated ion channels found in single-cell algae and used in optogenetics. Photon absorption leads to isomerization of the retinal cofactor, initiating a number of reactions that are referred to as photocycle and involve formation of the ion-conducting state. In this thesis, the photocycle mechanism of selected ChRs was investigated using FTIR (Fourier Transform Infrared) and UV-Vis spectroscopy, as well as retinal extraction and subsequent HPLC (High Performance Liquid Chromatography) analysis. Photoreceptors are optimized to use photon energy to drive conformational changes of the protein. Therefore, a fraction of the photon energy is stored by a transient distortion of the chromophore. In this thesis, it is shown that in ReaChR the transfer of the stored energy to the protein is largely affected by the protonation state of Glu163, being decelerated by protonated Glu163 due to an enhanced rigidity of the active site. In contrast, the chromophore in Chrimson relaxes upon photoisomerization, hinting at a distorted retinal geometry in the dark state, which is probably essential for its unprecedented bathochromic absorption. In addition to the chromophore geometry, the protonation state of Glu163 in ReaChR and the homologue Glu165 in Chrimson affects the stereoselectivity of the photoreaction. Another factor for stereoselectivity is Asp196 in ReaChR (Asp195 in C1C2) which deprotonates in the photocycle. Formation of the ion-conducting state in C1C2 and ReaChR involves water influx into the protein, facilitating transport of larger cations. Deprotonation of Glu130 in ReaChR (Glu129 in C1C2) alters the ion selectivity of the channel as known from electrophysiological experiments. In Chrimson, the extent of water influx is drastically reduced which favors the conductance of protons in agreement with electrophysiological characterization.
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Mackwood, Owen John. "Homeostatic and functional implications of interneuron plasticity." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19796.
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Die Erhaltung der Gehirnfunktion trotz Veränderungen im Organismus und dessen Umwelt erfordert homöostatische Mechanismen. Inhibitorische Interneurone spielen eine Schlüsselrolle bei Berechnungen und Homöostase im Gehirn. Es ist jedoch unklar, welcher Mechanismus diese Eigenschaften erzeugen kann. Diese Arbeit hat das Ziel, die homöostatischen Fähigkeiten solcher Interneurone zu bestimmen und die daraus resultierenden funktionellen Konsequenzen mit analytischen und numerischen Techniken zu ergründen.
Die zentrale Hypothese dieser Arbeit ist, dass Interneurone ihre Feuerraten modulieren, um langfristig die Aktivität exzitatorischer Neurone bei einem homöostatischen Sollwert zu halten. Wir beginnen mit einem normativen Ansatz und leiten eine Plastizitätsregel her, welche die Aktivität von Interneuronen regelt, um netzwerkweite Abweichungen vom Sollwert zu minimieren. Um die biologische Plausibilität zu erhöhen, liefern wir zwei Approximationen, bei denen jede Interneurone auf die exzitatorische Population reagiert, die sie inhibiert und zeigen, dass alle drei Varianten vergleichbare aber unterschiedliche homöostatische Fähigkeiten haben. Wir kontrastieren den normativen Ansatz mit Regeln, welche die Aktivität einer Interneurone verändern, wenn die Neuronen, die sie treiben, vom Sollwert abweichen. Diese Regeln erzeugen Konkurrenz zwischen Neuronen und führen daher zu zerstreuter Netzwerkaktivität.
Im zweiten Teil dieser Arbeit untersuchen wir, wie eine der approximierten Regeln die funktionellen Eigenschaften des sensorischen Kortex beeinflusst. Wir zeigen, dass sie mehrere experimentell Beobachtungen erklären kann, inklusive des Ko-Tunings von exzitatorischen und inhibitorischen Strömen und der Entwicklung von Zellverbänden.
Zusammenfassend liefert diese Arbeit neue Erkenntnisse darüber, wie die Regulierung der Interneuron-Aktivität für neuronale Netzwerke homöostatisch sein kann, und zeigt mögliche Auswirkungen auf die Entwicklung und Erhaltung der Gehirnfunktion auf.Preserving brain function despite ongoing changes inside the organism, and out in the world, necessitates homeostatic mechanisms. Inhibitory interneurons play a key role in both computation and homeostasis within the brain. However, it remains unclear if there is a mechanism that can account for both of these properties. This thesis therefore aims to determine the homeostatic capabilities of such interneurons and elucidate the resulting computational consequences, using analytical and numerical techniques. The central hypothesis of this thesis is that some interneurons slowly modulate their firing rates to maintain the long-term activity of excitatory neurons at a homeostatic set-point. Thus we begin with a normative approach, deriving a plasticity rule that regulates the activity of interneurons to minimise network-wide deviations from that set-point. In the interest of biological plausibility we also provide two approximations, both of which make each interneuron responsive to the excitatory population it inhibits, and show that all three variants exhibit comparable though distinct homeostatic capabilities. We contrast this normative approach by characterising the homeostatic properties of rules which instead alter the activity of an interneuron when the neurons that drive it deviate from the set-point. Those rules induce a competition between neurons, causing network activity to become sparse. In the second part of this thesis, we investigate how one of the approximate rules affects computational properties of sensory cortex. We show that it can account for several experimentally reported results, including co-tuning of excitatory and inhibitory currents, and the development of excitatory-inhibitory cell assemblies. In summation, this thesis provides new insight into how regulating interneuron activity can be homeostatic for neuronal networks, and reveals potential implications for development and preservation of brain function.
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Prüß, Harald. "Kir2 potassium channels in rat striatum are strategically localized to control basal ganglia function." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2004. http://dx.doi.org/10.18452/15031.
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Der Morbus Parkinson ist die häufigste Erkrankung der Basalganglien und wird durch einen Abbau der dopaminergen Neurone in der Substantia nigra des Mittelhirns verursacht. Um Wege zu finden, die Nebenwirkungen bisheriger Therapien dieser Erkrankung zu vermeiden, sollten neue Angriffspunkte für pharmakologische Interventionen gesucht werden. Prinzipiell ist dabei jeder Schritt einer Signaltransduktions-Kaskade zu prüfen. Dazu gehören präsynaptische Transmitterfreisetzung, G-Protein-gesteuerte Effektormechanismen oder Veränderungen prä- und postsynaptischer Potentiale, wie sie durch ein bestimmtes lokales Ionenkanalmuster festgelegt werden. Aufgrund ihrer enormen molekularen Vielfalt bei gleichzeitig weiter, aber spezifischer Verbreitung, stellen Kaliumkanäle interessante Angriffspunkte für neue therapeutische Strategien dar. Die vorliegende Arbeit untersucht die zelluläre und subzelluläre Verteilung aller Mitglieder der Kir2-Familie, einer Gruppe von Proteinen, die einwärts-gleichrichtende Kaliumkanäle bildet. Zu diesem Zweck wurden polyklonale, monospezifische, affinitätsgereinigte Antikörper gegen den wenig konservierten carboxyterminalen Anteil der Kir2.1-, Kir2.2-, Kir2.3- und Kir2.4-Proteine hergestellt. Alle Untereinheiten der Kir2-Familie wurden an den Somata und Dendriten der meisten striatalen Neurone nachgewiesen. Zwei dieser Kanäle zeigten jedoch ein inhomogenes Verteilungsmuster: Das "patch"-Kompartiment des Striatums wurde von der Expression des Kir2.3-Kanals ausgespart, und das Kir2.4-Protein wurde am stärksten auf den tonisch aktiven, cholinergen striatalen Interneuronen exprimiert. Diese beiden Strukturen stellen die Schlüsselstellen für die Kontrolle und Regulation der dopaminergen und cholinergen Transmission im Striatum dar, weswegen ihnen eine zentrale Rolle für die efferenten Projektionen der Basalganglien zukommt. Die nachgewiesene heterogene Lokalisation der Kir2.3- und Kir2.4-Untereinheit an diesen strategisch relevanten Strukturen macht diese Kanäle zu viel versprechenden Angriffspunkten für zukünftige Pharmakotherapien.Parkinson’s disease is the most frequent movement disorder caused by loss of dopaminergic neurons in the midbrain. Intentions to avoid side effects of conventional therapy should aim to identify additional targets for potential pharmacological intervention. In principle, every step of a signal transduction cascade, such as presynaptic transmitter release, type and occupation of postsynaptic receptors, G protein-mediated effector mechanisms, and the alterations of pre- or postsynaptic potentials as determined by the local ion channel composition, have to be considered. Due to their diversity and their widespread but distinct localizations, potassium channels represent interesting candidates for new therapeutic strategies. As a first step, the present report aimed to study the cellular and subcellular distribution of the individual members of the Kir2 family in the striatum, a group of proteins forming inwardly rectifying potassium channels. For this purpose polyclonal, monospecific, affinity purified antibodies against the less conserved carboxyterminal sequences from the Kir2.1, Kir2.2, Kir2.3, and Kir2.4 proteins were prepared. All subunits of the Kir2 family were detected on somata and dendrites of most striatal neurons. However, the distribution of two of them was not homogeneous. Striatal patch areas were largely devoid of the Kir2.3 protein, and the Kir2.4 subunit was most prominently expressed on the tonically active, giant cholinergic interneurons of the striatum. These two structures are among the key players in regulating dopaminergic and cholinergic neurotransmission within the striatum, and therefore are of major importance for the output of the basal ganglia. The heterogeneous localization of the Kir2.3 and the Kir2.4 subunits with respect to these strategic structures pinpoints these channel proteins as promising targets for future pharmacological efforts.
Libros sobre el tema "WW 220"
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W9M117, Cmipl. Mario Teaches Typing 2.0 C/Trb/Ww/Rental. AAA, 1997.
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Publishing, K. M. R. WW Instant Pot Freestyle Cookbook 2020: Easy and New WW Freestyle Recipes for Living and Eating Well Every Day. Independently Published, 2020.
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Watson, Emma. New Weight Watchers Freestyle Cookbook: Healthy and Tasty WW Freestyle Rapid Weight Loss Program 2020. Independently Published, 2020.
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Wijaya, Johan. Weight Watchers Freestyle Program 2020: Reset Your Health with Most Delicious WW Freestyle Smart Points Recipes. Independently Published, 2020.
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Scott, Victoria A. New Weight Watchers Cookbook 2020: Easy and Delicious WW SmartPoints Recipes under Blue, Green and Purple Plan. Independently Published, 2020.
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Karent, Isabella. Weight Watchers Air Fryer Cookbook 2020: Delicious Quick and Affordable WW Smart Points Air Fryer Recipes with Easy Budget. Independently Published, 2020.
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Cook, Robert. Weight Watchers Instant Pot Freestyle Cookbook #2020: Quick, Vibrant and Mouthwatering WW Instant Pot Smart Points Recipes for Lifelong Health. Independently Published, 2020.
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Mejia, Felix. New Weight Watchers Freestyle Cookbook 2020: The Complete WW Smart Points Cookbook-With 100+ Delicious Recipes for the Healthy Cook's Kitchen. Independently Published, 2020.
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Lombardi, Anthony. Weight Watchers: The Complete Weight Watchers Freestyle 2020 Cookbook for Beginners - Includes Quick, Easy, and Delicious WW Smart Points Recipes to Melt the Fat Away. Independently Published, 2020.
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Austin, Autumn. Weight Watchers Freestyle Meal Prep 2020: Selected and Most Delicious WW Smart Points Recipes with 30 Days Meal Plan to Lose Weight and Transform Your Body. Independently Published, 2020.
Capítulos de libros sobre el tema "WW 220"
1
Field, Fredric W. "Ww." In Key Concepts in Bilingualism. Macmillan Education UK, 2011. http://dx.doi.org/10.1007/978-0-230-34446-4_23.
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Sutherland, Jonathan, and Diane Canwell. "Ww." In Key Concepts in Business Practice. Macmillan Education UK, 2004. http://dx.doi.org/10.1007/978-0-230-21179-7_23.
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Charlesworth, Alan. "Ww." In Key Concepts in E-Commerce. Macmillan Education UK, 2007. http://dx.doi.org/10.1007/978-0-230-20672-4_23.
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Winstanley, Julie. "Ww." In Key Concepts in Psychology. Macmillan Education UK, 2006. http://dx.doi.org/10.1007/978-0-230-20818-6_23.
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Sutherland, Jonathan, and Diane Canwell. "Ww." In Key Concepts in Human Resource Management. Macmillan Education UK, 2004. http://dx.doi.org/10.1007/978-0-230-20464-5_23.
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Sutherland, Jonathan, and Diane Canwell. "Ww." In Key Concepts in International Business. Macmillan Education UK, 2004. http://dx.doi.org/10.1007/978-0-230-20466-9_23.
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Sutherland, Jonathan, and Diane Canwell. "Ww." In Key Concepts in Accounting and Finance. Macmillan Education UK, 2004. http://dx.doi.org/10.1007/978-0-230-20472-0_23.
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Stokes, Peter. "Vv Ww Xx Yy Zz." In Critical concepts in management and organization studies. Macmillan Education UK, 2011. http://dx.doi.org/10.1007/978-0-230-34556-0_19.
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Das, Amit, Simanti Bhattacharya, Angshuman Bagchi, and Rakhi Dasgupta. "Structural and Functional Characterization of Arabidopsis thaliana WW Domain Containing Protein F4JC80." In Computational Intelligence in Medical Informatics. Springer Singapore, 2014. http://dx.doi.org/10.1007/978-981-287-260-9_3.
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Zalewski, Piotr, Michał Jasztal, and Robert Rogólski. "Analiza możliwości zwiększenia udźwigu użytecznego samolotu Su-22 oraz MiG-29 dla potrzeb lotniczo-rakietowego systemu wynoszenia satelitów na niską orbitę okołoziemską." In Mechanika w Lotnictwie ML-XIX 2020. Instytut Techniczny Wojsk Lotniczych, Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2020. http://dx.doi.org/10.15632/ml2020/305-317.
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Praca stanowi kolejny etap rozwoju koncepcji lotniczo-rakietowego systemu wynoszenia niewielkich satelitów na niską orbitę okołoziemską przy wykorzystaniu samolotów MiG-29 oraz Su-22. W ramach tego etapu podjęto się zadania analizy możliwości zwiększenia udźwigu użytecznego tych samolotów. Stwierdzono, że cel ten można zrealizować, zmniejszając masę własną samolotu poprzez usunięcie elementów jego wyposażenia bojowego. Stąd też przeprowadzono analizę możliwości usunięcia elementów systemu sterowania bronią oraz współpracujących z nim urządzeń wykonawczych. Wykorzystując dokumentację techniczną rozważanych samolotów, dokonano szczegółowej analizy ww. systemów uzbrojenia w aspekcie ich demontażu, a wyniki prac zebrano w tabelach. W ramach pracy dokonano obliczeń wyważenia samolotu MiG-29 po usunięciu wybranych elementów. Do tego celu wykorzystano model masowy CAD samolotu opracowany w systemie NX. Obliczono, iż po demontażu zaproponowanej części wyposażenia bojowego samolotu MiG-29 środek masy całego obiektu misyjnego wędruje do 28% średniej cięciwy aerodynamicznej, co mieści się w dozwolonym przedziale (23,7%-30,5% MAC). W przypadku Su-22 stwierdzono, iż ponad 80% masy urządzeń wytypowanych do usunięcia leży w pobliżu środka masy samolotu, przez co ich usunięcie nie wpłynie znacząco na wyważenie samolotu.
Actas de conferencias sobre el tema "WW 220"
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Ebrahimpour, Mohammad K., J. Ben Falandays, Samuel Spevack, Ming-Hsuan Yang, and David C. Noelle. "WW-Nets: Dual Neural Networks for Object Detection." In 2020 International Joint Conference on Neural Networks (IJCNN). IEEE, 2020. http://dx.doi.org/10.1109/ijcnn48605.2020.9207407.
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