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1
Kihara, K., K. Sato, M. Ando, T. Morita, and H. Oshima. "Control of bilateral seminal emissions from ejaculatory ducts by a lumbar splanchnic nerve." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 265, no. 4 (October 1, 1993): R743—R748. http://dx.doi.org/10.1152/ajpregu.1993.265.4.r743.
Повний текст джерелаАнотація:
To investigate the route of efferent signals for seminal emissions from ejaculatory ducts (SEEDs), canine lumbar splanchnic nerves (LSNs) were electrically stimulated. SEED was confirmed by visual verification of seminal flow into the exposed posterior urethra. In intact dogs, electrical stimulation of an LSN caused bilateral SEEDs in 13 of 16 dogs examined, with a greater volume at the stimulated side. After transection of a unilateral hypogastric nerve, bilateral SEEDs occurred by electrical stimulation of the contralateral LSN in 11 of 14 dogs with a greater volume at the stimulated side and by the stimulation of the ipsilateral LSN in 13 of 15 dogs with a greater volume at the contralateral side. Contraction pressure of the epididymal tail under the same conditions harmonized with the above results. We conclude that each LSN generates bilateral SEEDs by sending signals to bilateral epididymal tails and that some of the signals through each LSN cross to the other side at the caudal mesenteric plexus and/or the prostatic plexus.
2
Villordo-Jimenez, Iclia, Noé Torres-Cruz, Marcelo M. Carvalho, Rolando Menchaca-Mendez, Mario E. Rivero-Angeles, and Ricardo Menchaca-Mendez. "A Selective-Awakening MAC Protocol for Energy-Efficient Data Forwarding in Linear Sensor Networks." Wireless Communications and Mobile Computing 2018 (2018): 1–18. http://dx.doi.org/10.1155/2018/6351623.
Повний текст джерелаАнотація:
We introduce the Selective-Awakening MAC (SA-MAC) protocol which is a synchronized duty-cycled protocol with pipelined scheduling for Linear Sensor Networks (LSNs). In the proposed protocol, nodes selectively awake depending on node density and traffic load conditions and on the state of the buffers of the receiving nodes. In order to characterize the performance of the proposed protocol, we present a Discrete-Time Markov Chain-based analysis that is validated through extensive discrete-event simulations. Our results show that SA-MAC significantly outperforms previous proposals in terms of energy consumption, throughput, and packet loss probability. This is particularly true under high node density and high traffic load conditions, which are expected to be common scenarios in the context of IoT applications. We also present an analysis by grade (i.e., the number of hops to the sink, which is located at one end of the LSN) that reveals that LSNs exhibit heterogeneous performance depending on the nodes’ grade. Such results can be used as a design guideline for future LSN implementations.
3
Wan, Chengpeng, Jiale Tao, Zaili Yang, and Di Zhang. "Evaluating recovery strategies for the disruptions in liner shipping networks: a resilience approach." International Journal of Logistics Management 33, no. 2 (October 15, 2021): 389–409. http://dx.doi.org/10.1108/ijlm-05-2021-0263.
Повний текст джерелаАнотація:
PurposeSince the start of the current century, the world at large has experienced uncertainties as a result of climate change, terrorism threats and increasing economic upheaval. These uncertainties create non-classical risks for global seaborne container trade and liner shipping networks (LSNs). The purpose of this paper is to establish a novel risk-based resilience framework to measure the effectiveness of different recovery strategies for the disruptions in LSNs in a quantitative manner.Design/methodology/approachBased on a resilience loss triangle model, an indicator of resilience–cost ratio is designed to measure the performance of LSNs during recovery. Four recovery strategies are proposed to test the rationality and feasibility of the developed indicator in aiding decision-making of LSNs from a resilience perspective.FindingsThe analysis results reveal that the superiorities of different recovery strategies vary depending on both the structures of LSNs and the specific requirements during recovery. Moreover, optimizing the sequence of ports being recovered will improve the overall recovery efficiency of the investigated LSN.Research limitations/implicationsAs an exploratory research trying to enrich the risk-based resilience evaluation of LSNs from a complex network perspective, only two attributes (e.g. port scare and economy) are considered at the current stage when estimating the time needed to fully recover the whole LSN. In future research, more attributes from the industry may be identified and incorporated into the proposed model to further extend its ability and application scopes.Practical implicationsThe findings will help to improve managerial understandings of recovery strategies to build more resilient LSNs. The proposed model has the capability to be tailored to tackle different types of risks in addition to the storm disaster condition.Originality/valueThe risk-based resilience framework and the resilience–cost ratio indicator are newly developed in this research. They can consider LSNs' structural resilience and the total costs that a recovery strategy needs to restore the whole system simultaneously.
4
Kihara, Kazunori, Kenji Sato, Kazuhiro Ishizaka, and Hiroyuki Oshima. "Preservation of ejaculatory function by reconstruction of the canine hypogastric nerve." Journal of Neurosurgery 88, no. 4 (April 1998): 726–33. http://dx.doi.org/10.3171/jns.1998.88.4.0726.
Повний текст джерелаАнотація:
Object. The hypogastric nerve (HGN) plays a crucial role in the primary functions of ejaculation: sperm transport through the vas deferens, secretion of prostatic fluid, and bladder neck closure. This study was undertaken to explore the possibility of restoring HGN function to the seminal tract and preserving its cross-innervation mechanism to the seminal tract after HGN—HGN reattachment. Methods. Responses of the vas deferens/epididymis, prostate, and bladder neck to electrical stimulation of the lumbar splanchnic nerve (LSN) or the HGN and occurrence of antegrade ejaculation as a result of manual penile stimulation were examined in dogs that had undergone HGN—HGN reattachment. Eighteen months after the procedure had been performed bilaterally, 23 LSNs were electrically stimulated. In 17 LSNs this stimulation elicited elevation of vasal pressure (12 nerves bilaterally); in 18 LNs, bladder neck pressure; and in 15 LSNs, prostate contraction. After retransection of the right HGN in the dogs that had undergone HGN—HGN reattachment, 11 right-sided LSNs were stimulated; in seven LSNs, the stimulation elicited elevation of vasal pressure (five bilaterally), in seven bladder neck pressure, and in six prostate contraction. Twelve left-sided LSNs were stimulated; in seven LSNs, the stimulation elicited elevation of vasal pressure (four bilaterally), in six bladder neck pressure, and in six prostate contracton. Each of the 12 HGN stimulations made proximal to the site that had been sutured in dogs that had HGN-HGN reattachment caused responses of the three organs specified above that were comparable to those in control dogs. Manual penile stimulation elicited antegrade ejaculation in all three dogs examined. Conclusions. The results of this study show that the function of the HGN in the seminal tract can be preserved after HGN—HGN reattachment and that restoration of its cross-innervation mechanism is possible.
5
Morgan, R., B. Nord, K. Bechtol, S. J. González, E. Buckley-Geer, A. Möller, J. W. Park, et al. "DeepZipper: A Novel Deep-learning Architecture for Lensed Supernovae Identification." Astrophysical Journal 927, no. 1 (March 1, 2022): 109. http://dx.doi.org/10.3847/1538-4357/ac5178.
Повний текст джерелаАнотація:
Abstract Large-scale astronomical surveys have the potential to capture data on large numbers of strongly gravitationally lensed supernovae (LSNe). To facilitate timely analysis and spectroscopic follow-up before the supernova fades, an LSN needs to be identified soon after it begins. To quickly identify LSNe in optical survey data sets, we designed ZipperNet, a multibranch deep neural network that combines convolutional layers (traditionally used for images) with long short-term memory layers (traditionally used for time series). We tested ZipperNet on the task of classifying objects from four categories—no lens, galaxy-galaxy lens, lensed Type-Ia supernova, lensed core-collapse supernova—within high-fidelity simulations of three cosmic survey data sets: the Dark Energy Survey, Rubin Observatory’s Legacy Survey of Space and Time (LSST), and a Dark Energy Spectroscopic Instrument (DESI) imaging survey. Among our results, we find that for the LSST-like data set, ZipperNet classifies LSNe with a receiver operating characteristic area under the curve of 0.97, predicts the spectroscopic type of the lensed supernovae with 79% accuracy, and demonstrates similarly high performance for LSNe 1–2 epochs after first detection. We anticipate that a model like ZipperNet, which simultaneously incorporates spatial and temporal information, can play a significant role in the rapid identification of lensed transient systems in cosmic survey experiments.
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Lanic, Helene, Jerome Kraut, Romain Modzelewski, Florian Clatot, Jean-Michel Picquenot, Nathalie Contentin, Pascal Lenain, et al. "Clinical Relevance Of Cachexia Assessed By An Anthropometric Tool In Elderly Patients With Diffuse Large B-Cell Lymphoma Treated By Immunochemotherapy." Blood 122, no. 21 (November 15, 2013): 2926. http://dx.doi.org/10.1182/blood.v122.21.2926.2926.
Повний текст джерелаАнотація:
Abstract Background Cancer Cachexia is a metabolic syndrome that can be present even in absence of weight loss and associated with significantly impaired survival. Muscle wasting represents a key-symptom of this syndrome and we recently demonstrated the strong prognosis impact of sarcopenia assessed by computed tomography (CT)-scan in diffuse large B-cell lymphoma (DLBCL) (Lanic et al. Leukemia & Lymphoma 2013). Conversely, the clinical relevance of loss of fat mass (adipopenia) remains unclear. The aim of this study was (i) to investigate the prognostic impact of a multidimensional tool combining a nutritional parameter (albuminemia) and body composition measurements (skeletal muscle and body fat composition) in elderly patients with DLBCL treated by chemotherapy and rituximab (R) (ii) to document the evolution of sarcopenia after immunochemotherapy. Methods This retrospective analysis included 80 DLBCL patients older than 70 years (y) and treated by R-CHOP or R-miniCHOP. Skeletal muscle (SM), visceral (V) and subcutaneal (S) adipose (A) tissues were measured by analysis of stored CT images at the Lumbar vertebrae 3 (L3) level. The surface of the muscular and adipose tissues was selected according to CT Hounsfield unit. Values were normalized for stature to calculate the L3 SM index (LSMI, in cm2/m2), the LVAI and the LSAI and used to define sarcopenia and visceral/subcutaneal adipopenia. Results The characteristics of the patients were as follows: median age = 78 y [70-95]; 36 males; IPI 0-2 = 22, 3-5 = 58; treatment by R-CHOP (n = 45) or R-miniCHOP (n = 35); median body mass index (BMI; in kg/m2) = 23.9. According to the sex-specific defined cut-offs for LSMI (< 55.8 cm²/m² for men and 38.9 cm²/m² for women), 44 DLBCL patients (55 %, 23 males) were considered as sarcopenic. With a median follow-up of 39 months, the 2y overall survival (OS) in the sarcopenic population was 46% as compared to 84% in the non-sarcopenic group (HR = 3.12; CI95%, 1.66-5.88; p=0.0004). The median LSAI was 76.3 cm2/m2 [10-167] in females and 47.4 cm2/m2[22-100] in males. The median LVSAI was 43.5 cm2/m2[3-141] in females and 50.4 cm2/m2[14-159] in males. Adipopenia, defined by a low LVAI and/or a low LSAI was also highly predictive of the outcome. The 2y OS of the low LVAI population was 48% as compared to 82% for the non-adipopenic group (HR = 2.20; CI95%, 1.19-4.05; p=0.01). The 2y OS in the low LSAI population was 48% as compared to 80% in the non-adipopenic group (HR = 2.28; CI95%, 1.23-4.21; p=0.008). A Three-point cachexia score (CS) including adipopenia, sarcopenia and hypo-albuminemia (defined by an albuminemia < 35 g/L) was build and delineates three distinct risk-groups (Figure 1). More importantly the CS remains predictive of the prognosis in a multivariate analysis including BMI (< or >= 25 kg/m2), age (< or >= 80y), IPI and gender (HR=2.5; CI95%= 1.14-5.39; p =0.02). LMSI was subsequently reassessed in thirty seven patients during the routine CT scan follow-up [mean = 10 months after pre-treatment CT scan (range 2.8-19.2)]. 15 (40%) patients displayed a 5% decrease of their LSMI, whereas 13 (35%) and 9 (25%) displayed no significant change or increase (>5%) of the LMSI respectively. Conclusion Our study demonstrates that sarcopenia and adipopenia estimated by CT-scan define cachexia more accurately than BMI or weight loss in elderly DLBCL patients. These factors can be integrated in a cachexia scoring tool which predicts the outcome independently of the BMI and of the IPI. CT scan follow-up indicates that cachexia is a reversible process that should be integrated as part of the therapeutic target in combination with lymphoma treatment. A prospective multicentric trial (registered as NCT01715961/Clinical.gov) is ongoing to validate these anthropometric and nutritional parameters and compare to geriatric assessment scales. Disclosures: No relevant conflicts of interest to declare.
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Huber, S., S. H. Suyu, D. Ghoshdastidar, S. Taubenberger, V. Bonvin, J. H. H. Chan, M. Kromer, U. M. Noebauer, S. A. Sim, and L. Leal-Taixé. "HOLISMOKES." Astronomy & Astrophysics 658 (February 2022): A157. http://dx.doi.org/10.1051/0004-6361/202141956.
Повний текст джерелаАнотація:
The Hubble constant (H0) is one of the fundamental parameters in cosmology, but there is a heated debate around the > 4σ tension between the local Cepheid distance ladder and the early Universe measurements. Strongly lensed Type Ia supernovae (LSNe Ia) are an independent and direct way to measure H0, where a time-delay measurement between the multiple supernova (SN) images is required. In this work, we present two machine learning approaches for measuring time delays in LSNe Ia, namely, a fully connected neural network (FCNN) and a random forest (RF). For the training of the FCNN and the RF, we simulate mock LSNe Ia from theoretical SN Ia models that include observational noise and microlensing. We test the generalizability of the machine learning models by using a final test set based on empirical LSN Ia light curves not used in the training process, and we find that only the RF provides a low enough bias to achieve precision cosmology; as such, RF is therefore preferred over our FCNN approach for applications to real systems. For the RF with single-band photometry in the i band, we obtain an accuracy better than 1% in all investigated cases for time delays longer than 15 days, assuming follow-up observations with a 5σ point-source depth of 24.7, a two day cadence with a few random gaps, and a detection of the LSNe Ia 8 to 10 days before peak in the observer frame. In terms of precision, we can achieve an approximately 1.5-day uncertainty for a typical source redshift of ∼0.8 on the i band under the same assumptions. To improve the measurement, we find that using three bands, where we train a RF for each band separately and combine them afterward, helps to reduce the uncertainty to ∼1.0 day. The dominant source of uncertainty is the observational noise, and therefore the depth is an especially important factor when follow-up observations are triggered. We have publicly released the microlensed spectra and light curves used in this work.
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Jawhar, Imad, Sheng Zhang, Jie Wu, Nader Mohamed, and Mohammad M. Masud. "Distributed Algorithms for Multiple Path Backbone Discovery in Thick Linear Sensor Networks." Journal of Sensor and Actuator Networks 10, no. 3 (July 16, 2021): 49. http://dx.doi.org/10.3390/jsan10030049.
Повний текст джерелаАнотація:
Continued advancements in microprocessors, electronics, and communication technology have led to the design and development of sensing devices with increased functionalities, smaller sizes, larger processing, storage, and communication capabilities, and decreased cost. A large number of these sensor nodes are used in many environmental, infrastructure, commercial, and military monitoring applications. Due to the linearity of a good number of the monitored structures such as oil, gas, and water pipelines, borders, rivers, and roads, the wireless sensor networks (WSNs) that are used to monitor them have a linear topology. This type of WSN is called a linear sensor network (LSN). In this paper, two distributed algorithms for topology discovery in thick LSNs are presented: the linear backbone discovery algorithm (LBD) and the linear backbone discovery algorithm with x backbone paths (LBDx). Both of them try to construct a linear backbone for efficient routing in LSNs. However, the LBD algorithm has the objective of minimizing the number of messages used during the backbone discovery process. On the other hand, the LBDx algorithm focuses on reducing the number of hops of the data messages transmitted from the nodes to the sink. LBD and LBDx exhibit good properties and efficient performance, which are confirmed by extensive simulations.
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Zhou, Jingmiao, Yuzhe Zhao, and Xingwen Niu. "Two-Phase Optimization Models for Liner Shipping Network Based on Hub Ports Cooperation: From the Perspective of Supply-Side Reform in China." Journal of Advanced Transportation 2021 (April 5, 2021): 1–18. http://dx.doi.org/10.1155/2021/6639218.
Повний текст джерелаАнотація:
From the perspective of supply-side reform in China, it is hard for COSCO Shipping, a merged company with a strong shipping capacity, to abandon the container shipping market. Meanwhile, the new company could cooperate with new strategic ports along the Maritime Silk Road in liner service. Against this backdrop, this paper aims to optimize the liner shipping network (LSN) from strategic, tactical, and operational levels and help the merged shipping company adjust its operational measures according to market changes. The optimization towards different levels of decision-making process is a new research of highly practical values. Specifically, this paper created two-phase optimization models for LSN based on the selection of hub ports. In Network Assessment (NA) phase, the LSNs of two types of hub ports selected are designed and assessed on strategic and tactical levels, and the primary and secondary routes are identified; in Network Operation (NO) phase, the “path-based flow” formulations are proposed from the operational level, considering operational measures including demand rejection and flow integration. The models in both phases are mixed-integer linear programming (MILP), but are solved by different tools: CPLEX for the NA phase models and the Genetic Algorithm (GA) for the NO phase models due to the computational complexity of the latter problem. Then, a computational experiment is performed on the LSN of COSCO Shipping on the Persian Gulf trade lane. The results have proved the effectiveness of the methodology and inspired important countermeasures for the merged shipping company.
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Agarwalla, Sanjib K., and Patrick Huber. "LSND reloaded." Physics Letters B 696, no. 4 (February 2011): 359–61. http://dx.doi.org/10.1016/j.physletb.2010.12.038.
Повний текст джерела
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Meeporn, Keerati, Prasit Thongbai, Teerapon Yamwong, and Santi Maensiri. "Greatly enhanced dielectric permittivity in La1.7Sr0.3NiO4/poly(vinylidene fluoride) nanocomposites that retained a low loss tangent." RSC Advances 7, no. 28 (2017): 17128–36. http://dx.doi.org/10.1039/c7ra01675a.
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Kawada, Toru, Kazunori Uemura, Koji Kashihara, Yintie Jin, Meihua Li, Can Zheng, Masaru Sugimachi, and Kenji Sunagawa. "Uniformity in dynamic baroreflex regulation of left and right cardiac sympathetic nerve activities." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 284, no. 6 (June 1, 2003): R1506—R1512. http://dx.doi.org/10.1152/ajpregu.00736.2002.
Повний текст джерелаАнотація:
Functional laterality of cardiac sympathetic nerve stimulation in chronotropic and inotropic effects is well known. Whether left (LSNA) and right (RSNA) cardiac sympathetic nerve activities show laterality during dynamic baroreflex activation remains to be determined. In nine anesthetized, vagotomized, and aortic-denervated rabbits, we randomly perturbed intracarotid sinus pressure (CSP) in both carotid sinus regions while simultaneously recording LSNA and RSNA. The baroreflex neural arc transfer function from CSP to LSNA and from CSP to RSNA revealed derivative characteristics, i.e., the magnitude of LSNA and RSNA responses became greater as the input frequency of CSP perturbation increased. The average slope of increasing gain in the frequencies between 0.03 and 0.3 Hz showed no difference between LSNA and RSNA responses (9.7 ± 2.9 vs. 9.7 ± 3.1 dB/decade, means ± SD). The amplitude ratio and phase difference between LSNA and RSNA approximated unity and zero radians, respectively, in the frequencies from 0.01 to 1 Hz. In addition, the LSNA-RSNA relationship during stepwise CSP perturbation from 40 to 160 mmHg showed a straight line ( r 2ranged from 0.969 to 0.999). These findings indicate no laterality in the dynamic as well as static baroreflex regulation of LSNA and RSNA as far as grouped axonal activity is concerned.
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Xu, Ling, John P. Collister, John W. Osborn, and Virginia L. Brooks. "Endogenous ANG II supports lumbar sympathetic activity in conscious sodium-deprived rats: role of area postrema." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 275, no. 1 (July 1, 1998): R46—R55. http://dx.doi.org/10.1152/ajpregu.1998.275.1.r46.
Повний текст джерелаАнотація:
This study tests the hypothesis that the area postrema (AP) is necessary for endogenous ANG II to chronically maintain lumbar sympathetic nerve activity (LSNA) and heart rate (HR) in conscious sodium-deprived rats. The effect of the ANG II type 1-receptor antagonist, losartan, on LSNA and HR was determined in rats that were either AP lesioned (APX) or sham lesioned. The sham rats were divided into groups, with (SFR) or without (SAL) food restriction, to control for the decreased food intake of APX rats. Before losartan, basal mean arterial pressure (MAP), HR, and baroreflex control of LSNA and HR were similar between groups, with the exception of lower maximal reflex LSNA and higher maximal gain of the HR-MAP curve in APX rats. In all groups, losartan similarly shifted ( P < 0.01) the LSNA-MAP curve to the left without altering maximal gain. Losartan also decreased ( P < 0.05) minimal LSNA in all groups, and suppressed ( P < 0.01) maximal LSNA (% of control) in SFR (240 ± 13 to 205 ± 15) and SAL (231 ± 21 to 197 ± 26) but not APX (193 ± 10 to 185 ± 8) rats. In general, losartan similarly shifted the HR-MAP curve to a lower MAP in all groups. The results suggest that the AP is not necessary for endogenous ANG II to chronically support LSNA and HR at basal and elevated MAP levels in sodium-deprived rats. However, the AP is required for endogenous ANG II to increase maximal reflex LSNA at low MAP levels.
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Guarçoni Netto, Angelo, Luis Marchi, Gabriel Pokorny, Rodrigo Amaral, Rubens Jensen, Raphael Pratali, Carlos Fernando Herrero, et al. "TRANSLATION AND ADAPTATION OF THE “LUMBAR STIFFNESS DISABILITY INDEX” QUESTIONNAIRE INTO PORTUGUESE." Coluna/Columna 18, no. 2 (June 2019): 127–29. http://dx.doi.org/10.1590/s1808-185120191802196734.
Повний текст джерелаАнотація:
ABSTRACT Objective: To develop a version of the Lumbar Stiffness Disability Index (LSDI), translated into Portuguese and culturally adapted for the Brazilian population. Methods: The well-established process of translation into Portuguese and back translation into English was used together with cultural adaptation. Results: Five bilingual translators (English and Portuguese) performed the translation of the Lumbar Stiffness Disability Index (LSDI) from English to Portuguese based on interactive discussions used to arrive at a consensus translation. The translated version of LSDI was then translated into English by a native English-speaking translator who did not know the concepts involved in LSDI. The original LSDI and back translation were compared by a committee formed by the translators responsible for translating the original into Portuguese and a North-American spine surgeon, and because they were considered equivalent, the final version of the LSDI translated into Portuguese and culturally adapted was defined. Conclusions: In order to facilitate global and cross-cultural comparisons of the influence of lumbar stiffness related to spinal arthrodesis in daily activities, this study presents a version of LSDI that has been translated into Portuguese and culturally adapted for the Brazilian population. Level of Evidence; Not Applicable. Prospective Study.
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Costley, Jamie, and Christopher Henry Lange. "Video lectures in e-learning." Interactive Technology and Smart Education 14, no. 1 (April 18, 2017): 14–30. http://dx.doi.org/10.1108/itse-08-2016-0025.
Повний текст джерелаАнотація:
Purpose Because student viewership of video lectures serves as an important aspect of e-learning environments, video lectures should be delivered in a way that enhances the learning experience. The delivery of video lectures through diverse forms of media is a useful approach, which may have an effect on student learning, satisfaction, engagement and interest (LSEI), as well as future behavioral intentions (FBI). Furthermore, research has shown the value that LSEI has on learner achievement within online courses, as well as its value in regards to student intention to continue learning in such courses. The purpose of this study is to investigate the relationships between media diversity, LSEI and FBI in hopes of enhancing the e-learning experience. Design/methodology/approach This study surveyed a group of students (n = 88) who participated in cyber university classes in South Korea to investigate the correlations between media diversity and lecture viewership, effects of lecture viewership on LSEI and FBI, effects of media diversity on LSEI and FBI as well as the correlation between LSEI and FBI. Findings Results show no relationship between media diversity and viewership. Both lecture viewership and media diversity were positively correlated with LSEI. However, neither media diversity nor viewership was positively correlated with FBI. Finally, LSEI was positively correlated with FBI. Originality/value This paper looks at how video lectures affect LSEI. Past research has generally looked at learning, satisfaction, engagement and interest as separate entities that are affected by instructional aspects of online learning. Because of their interrelationships with each other, this study combines them as one construct, making a stronger case for their combined association.
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Soker, Noam. "Powering Luminous Core Collapse Supernovae with Jets." Astrophysical Journal 935, no. 2 (August 1, 2022): 108. http://dx.doi.org/10.3847/1538-4357/ac822d.
Повний текст джерелаАнотація:
Abstract I examine recent fittings of luminous supernovae (LSNe) with extra energy sources of magnetar and helium burning and find that in about half of these LSNe the fitting parameters have some problems. In some LSNe the total energy of these two energy sources is larger than the kinetic energy of the ejecta that the fitting yields. In some other LSNe the total energy of the delayed neutrino explosion mechanism and these two extra sources combined is smaller than the kinetic energy that the fitting yields. These difficulties suggest that, like earlier claims that jets power superluminous supernovae (SLSNe), jets also power the less luminous LSNe. A magnetar might also supply energy. However, in most cases jets supply more energy than the magnetar, during the explosion and possibly at late times. I strengthen an earlier claim that jets launched at magnetar birth cannot be ignored. I explain the trend of maximum rise time for a given luminosity of hydrogen deficient core collapse supernovae, in particular LSNe and SLSNe, with a toy model of jets that are active for a long time after explosion.
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Pauling, John D., Jacqueline A. Shipley, Darren J. Hart, Anita McGrogan, and Neil J. McHugh. "Use of Laser Speckle Contrast Imaging to Assess Digital Microvascular Function in Primary Raynaud Phenomenon and Systemic Sclerosis: A Comparison Using the Raynaud Condition Score Diary." Journal of Rheumatology 42, no. 7 (June 1, 2015): 1163–68. http://dx.doi.org/10.3899/jrheum.141437.
Повний текст джерелаАнотація:
Objective.Evaluate objective assessment of digital microvascular function using laser speckle contrast imaging (LSCI) in a cross-sectional study of patients with primary Raynaud phenomenon (RP) and systemic sclerosis (SSc), comparing LSCI with both infrared thermography (IRT) and subjective assessment using the Raynaud Condition Score (RCS) diary.Methods.Patients with SSc (n = 25) and primary RP (n = 18) underwent simultaneous assessment of digital perfusion using LSCI and IRT with a cold challenge on 2 occasions, 2 weeks apart. The RCS diary was completed between assessments. The relationship between objective and subjective assessments of RP was evaluated. Reproducibility of LSCI/IRT was assessed, along with differences between primary RP and SSc, and the effect of sex.Results.There was moderate-to-good correlation between LSCI and IRT (Spearman rho 0.58–0.84, p < 0.01), but poor correlation between objective assessments and the RCS diary (p > 0.05 for all analyses). Reproducibility of IRT and LSCI was moderate at baseline (ICC 0.51–0.63) and immediately following cold challenge (ICC 0.56–0.86), but lower during reperfusion (ICC 0.3–0.7). Neither subjective nor objective assessments differentiated between primary RP and SSc. Men reported lower median daily frequency of RP attacks (0.82 vs 1.93, p = 0.03). Perfusion using LSCI/IRT was higher in men for the majority of assessments.Conclusion.Objective and subjective methods provide differing information on microvascular function in RP. There is good convergent validity of LSCI with IRT and acceptable reproducibility of both modalities. Neither subjective nor objective assessments could differentiate between primary RP and SSc. Influence of sex on subjective and objective assessment of RP warrants further evaluation.
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Al-Shalabi, Emad W., Kamy Sepehrnoori, and Gary Pope. "Geochemical Interpretation of Low-Salinity-Water Injection in Carbonate Oil Reservoirs." SPE Journal 20, no. 06 (December 18, 2015): 1212–26. http://dx.doi.org/10.2118/169101-pa.
Повний текст джерелаАнотація:
Summary The advantages of using the low-salinity-water-injection (LSWI) technique to improve oil recovery in carbonates are reported in the literature; however, the mechanism behind it is still uncertain. This paper represents a comparison between two geochemical simulators [UTCHEM (UTCHEM manual, 2000) and PHREEQC (Parkhurst and Appelo 2013)] through modeling fluid- and solid-species concentrations of a recently published LSWI coreflood. Moreover, an attempt to interpret the mechanism controlling the LSWI effect on oil recovery from carbonates is presented on the basis of the findings of this work. The LSWI technique is case-dependent, and hence, the findings cannot be generalized.
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Al-Shalabi, Emad W., Kamy Sepehrnoori, and Gary Pope. "Mechanistic Modeling of Oil Recovery Caused by Low-Salinity-Water Injection in Oil Reservoirs." SPE Journal 21, no. 03 (June 15, 2016): 0730–43. http://dx.doi.org/10.2118/172770-pa.
Повний текст джерелаАнотація:
Summary Low-salinity-water injection (LSWI) is an emerging way to improve waterflood performance at low cost under certain conditions. The effect of LSWI on the oil recovery from carbonate formations has been well-documented in the laboratory and to a limited extent in the field. In this study, a mechanistic geochemical model is proposed that addresses the effect on oil recovery of different geochemical reactions resulting from LSWI. The proposed model was used to history match recently published corefloods by use of the UTCHEM (2000) mechanistic reservoir simulator. Moreover, other sets of corefloods were chosen to validate the proposed LSWI mechanistic model. The geochemical model in the UTCHEM simulator was modified to calculate the molar Gibbs free energy of the brine. In the proposed LSWI mechanistic model, the relative permeability curves, including the residual oil saturation (ROS), are functions of the molar Gibbs free energy. Coreflood experiments were simulated and history matched by use of the proposed model. The proposed LSWI mechanistic model was further extended to include weakly oil-wet to mixed-wet carbonate rocks. The mechanistic model captures the effects on oil recovery of both wettability alteration and/or dissolution/fines migration through changes in the molar Gibbs free energy. This model can now be used for oil-recovery predictions and optimization of LSWI field applications.
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Alemu, Yideg, and Degefa Tolossa. "Livelihood Impacts of Large-Scale Agricultural Investments Using Empirical Evidence from Shashamane Rural District of Oromia Region, Ethiopia." Sustainability 14, no. 15 (July 25, 2022): 9082. http://dx.doi.org/10.3390/su14159082.
Повний текст джерелаАнотація:
The impact of Large Scale Agricultural Investments (LSAI) on local people’s livelihood improvement has received less attention than it deserves in Ethiopia in general, and the Oromia regional states in particular. The main objective of this study was to analyze the impact of LSAI, which began operations in 2008, on 10,000 hectares of fertile land in the Shashamane rural district of Oromia region, Ethiopia to enhance the quality of life of the local people. A quasi-experimental study design strategy was used to achieve this goal. We obtained primary data from 300 households, comprising 134 treatment homes (households in a community with LSAI) from the Shashamane rural district and 166 control households (households in a community without LSAI) from the Shala district using systematic random sampling. Analysis was undertaken using principal component analysis (PCA) and propensity score matching (PSM). The Sustainable Livelihoods Framework (SLF) was used to examine the theoretical concept with empirical findings. According to the Average Treatment Effect on Treated (ATT) results, the treated households’ natural, human, and financial capital were −0.91, −0.81, and −0.15 less than control families, respectively. Loss of household livelihoods has deepened and exacerbated local poverty. Businesses have not mechanized and controlled these sizable portions of the parcel; instead, peasants have worked on them and exploited the idle parcel. The research suggests that the government’s pro-LSAI investment policy is desirable. However, weak institutional frameworks for protecting local people’s livelihoods as well as LSAI malpractice and the lack of continuous follow-up are causing the LSAI policy to fail. To mitigate the negative impact of LSAI on peasants, it is necessary to consider the local people’s livelihoods, responsive institutions, and accountable ventures.
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Lee, Jun-Hyuk, Hye-Sun Lee, Byoung-Kwon Lee, Yu-Jin Kwon, and Ji-Won Lee. "Relationship between Muscle Mass and Non-Alcoholic Fatty Liver Disease." Biology 10, no. 2 (February 5, 2021): 122. http://dx.doi.org/10.3390/biology10020122.
Повний текст джерелаАнотація:
Although sarcopenia is known to be a risk factor for non-alcoholic fatty liver disease (NAFLD), whether NAFLD is a risk factor for the development of sarcopenia is not clear. We investigated relationships between NAFLD and low skeletal muscle mass index (LSMI) using three different datasets. Participants were classified into LSMI and normal groups. LSMI was defined as a body mass index (BMI)-adjusted appendicular skeletal muscle mass <0.789 in men and <0.512 in women or as the sex-specific lowest quintile of BMI-adjusted total skeletal muscle mass. NAFLD was determined according to NAFLD liver fat score or abdominal ultrasonography. The NAFLD groups showed a higher hazard ratios (HRs) with 95% confidence intervals (CIs) for LSMI than the normal groups (HRs = 1.21, 95% CIs = 1.05–1.40). The LSMI groups also showed a higher HRs with 95% CIs for NAFLD than normal groups (HRs = 1.56, 95% CIs = 1.38–1.78). Participants with NAFLD had consistently less skeletal muscle mass over 12 years of follow-up. In conclusion, LSMI and NAFLD showed a relationship. Maintaining muscle mass should be emphasized in the management of NAFLD.
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Das, B., B. Borah, and S. Bhattacharyya. "COMPARATIVE ANALYSIS OF CARBOXYMETHYL CELLULOSE AND PARTIALLY HYDROLYZED POLYACRYLAMIDE – LOW-SOLID NONDISPERSED DRILLING MUD WITH RESPECT TO PROPER-TY ENHANCEMENT AND SHALE INHIBITION." Resource-Efficient Technologies, no. 2 (August 26, 2020): 24–33. http://dx.doi.org/10.18799/24056537/2020/2/262.
Повний текст джерелаАнотація:
During drilling, different problems are encountered that can interfere with smooth drilling processes, including the accumulation of cuttings, reduced penetration rates, pipe sticking, loss of wellbore stability, and loss of circulation. These problems are generally encountered with conventional drilling mud, such as the bentonite–barite mud system. Formation damage is the most common problem encountered in bentonite mud systems with high solid content. In this work, we aimed to formulate two low-solid nondispersed (LSND) muds: carboxymethyl cellulose (CMC)–LSND mud and partially hydrolyzed polyacrylamide (PHPA)–LSND mud. A comparative analysis was performed to evaluate their property enhancements. LSND muds aid in maintaining hole stability and proper cutting removal. The results of this work show that the addition of both CMC and PHPA helps to improve drilling fluid properties; however, the PHPA–LSND mud was found to be superior. Shale swelling is a major concern in the petroleum industry, as it causes various other problems, such as pipe sticking, low penetration rates, and bit wear. The effect of these two LSND polymer muds in inhibiting shale swelling was analyzed using shale collected from the Champhai district of Mizoram, India.
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Al-Shalabi, Emad Waleed, Kamy Sepehrnoori, and Gary Pope. "Mysteries behind the Low Salinity Water Injection Technique." Journal of Petroleum Engineering 2014 (May 25, 2014): 1–11. http://dx.doi.org/10.1155/2014/304312.
Повний текст джерелаАнотація:
Low salinity water injection (LSWI) is gaining popularity as an improved oil recovery technique in both secondary and tertiary injection modes. The objective of this paper is to investigate the main mechanisms behind the LSWI effect on oil recovery from carbonates through history-matching of a recently published coreflood. This paper includes a description of the seawater cycle match and two proposed methods to history-match the LSWI cycles using the UTCHEM simulator. The sensitivity of residual oil saturation, capillary pressure curve, and relative permeability parameters (endpoints and Corey’s exponents) on LSWI is evaluated in this work. Results showed that wettability alteration is still believed to be the main contributor to the LSWI effect on oil recovery in carbonates through successfully history matching both oil recovery and pressure drop data. Moreover, tuning residual oil saturation and relative permeability parameters including endpoints and exponents is essential for a good data match. Also, the incremental oil recovery obtained by LSWI is mainly controlled by oil relative permeability parameters rather than water relative permeability parameters. The findings of this paper help to gain more insight into this uncertain IOR technique and propose a mechanistic model for oil recovery predictions.
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Marasović, Slaven, Joep Crompvoets, and Vesna Poslončec-Petrić. "Implementing a WebGIS Solution in the City of Sinj in Accordance with the Needs of the City Stakeholders." Kartografija i geoinformacije 20, no. 36 (February 15, 2022): 38–59. http://dx.doi.org/10.32909/kg.20.36.3.
Повний текст джерелаАнотація:
The paper describes the establishment of a webGIS pilot project in the city of Sinj, based on the research of the development of local spatial data infrastructure (LSDI) as described in the doctoral thesis (Marasović 2020). A set of LSDI development indicatorswere tested in the pilot project. The indicators to be tested were discovered in the mentioned doctoral thesis using statistical regression, statistical correlation and focus groups. The following key indicators have been identified: 1) funding from the local level, 2) awareness, 3) support for development from the decision makers, and 4) administration and citizens recognized as the main LSDI user groups. As an example of LSDI, most main stakeholders of the city of Sinj were interviewed and mapped according to their relevant capabilities, working processes and interaction between the main stakeholders. All the identified indicators were confirmed. The pilot project confirmed that the decision on investment in LSDI from the local level decision makers is essential for its implementation. For such a decision, raising the awareness of the decision makers and citizens about the benefits of LSDI is vital. Citizens and city administration were mapped as two stakeholders which interact most among the stakeholders. Delegating an employee responsible for the implementation and support from the decision makers during the implementation process are essential for success. Human Resources and Public Relationships management activities were recognized as very important in the process of raising awareness of LSDI. decision-makers.
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Dieterle, Byron D. "CHOOZ and LSND." Nuclear Physics B - Proceedings Supplements 59, no. 1-3 (November 1997): 283–88. http://dx.doi.org/10.1016/s0920-5632(97)00453-2.
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Thomasen, Henning, Klaus Steuhl, and Daniel Meller. "Optische Rehabilitation nach Limbusstammzellinsuffizienz: aktuelle Behandlungsmöglichkeiten und Entwicklungen." Klinische Monatsblätter für Augenheilkunde 235, no. 07 (September 12, 2017): 801–8. http://dx.doi.org/10.1055/s-0043-106306.
Повний текст джерелаАнотація:
ZusammenfassungDie Behandlung der Limbusstammzellinsuffizienz (LSZI) stellt eine Herausforderung in der Augenheilkunde dar. Es handelt sich um eine Störung der Augenoberfläche, die durch eine nicht funktionale Regeneration des kornealen Epithels entsteht. Die LSZI wird sowohl von hereditären als auch erworbenen Grunderkrankungen verursacht. Je nach Ausprägung unterscheidet man dabei zwischen einer partiellen oder totalen LSZI sowie zwischen uni- oder bilateralen Fällen. Die Behandlung richtet sich nach der Ätiologie der Erkrankung. Es stehen zu diesem Zweck eine Reihe von Techniken zur Verfügung, darunter fallen die Anwendung von Amniontransplantationen, die Transplantation von Limbusgewebe oder die Anwendung von ex vivo expandierten Zellen. In dieser Übersichtsarbeit werden die aktuellen Behandlungsoptionen für die LSZI zusammengefasst sowie neue Entwicklungen auf diesem Gebiet vorgestellt.
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Knudsen, Kristine, Joergen Thorup, Rune Strandby, Rikard Ambrus, Linea Ring, and Inge Ifaoui. "Laser Speckle Contrast Imaging to Evaluate Bowel Lesions in Neonates with NEC." European Journal of Pediatric Surgery Reports 05, no. 01 (January 2017): e43-e46. http://dx.doi.org/10.1055/s-0037-1606196.
Повний текст джерелаАнотація:
Background Necrotizing enterocolitis (NEC) is the most frequent surgical emergency in newborns. Intestinal ischemia is considered a factor that precedes the development of NEC lesions. Laser speckle contrast imaging (LSCI) can be used to assess tissue microcirculation. We evaluated if LSCI may help to detect intestinal regions with reduced microcirculation in NEC. Case Report A male patient (gestational age, 26 [3/7] weeks; birth weight, 600 g) showed clinical signs of NEC 28 days after birth. X-ray revealed pneumatosis intestinalis and portal gas. Laparotomy showed NEC lesions with signs of transmural ischemia in the terminal ileum and cecum. Surgical resection lines (RLs) were marked, followed by LSCI measurements and resection of the bowel between the two RLs. Post hoc LSCI analyses were conducted on both sides of the proximal and distal RL. Low-flux values, indicating reduced microcirculation, were found in the macroscopically assessed necrotic bowel at the proximal RL, whereas higher flux values, indicating sufficient microcirculation, were found in the macroscopically assessed normal bowel. Discussion This study is the first description of intra-abdominal use of LSCI to evaluate tissue microcirculation in relation to NEC lesions. LSCI could be a valuable tool to distinguish between ischemic and nonischemic bowel in neonates undergoing surgery for NEC.
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Margouta, Anastasia, Panagiota Anyfanti, Antonios Lazaridis, Barbara Nikolaidou, Konstantinos Mastrogiannis, Anastasia Malliora, Aikaterini Patsatsi, et al. "Blunted Microvascular Reactivity in Psoriasis Patients in the Absence of Cardiovascular Disease, as Assessed by Laser Speckle Contrast Imaging." Life 12, no. 11 (November 6, 2022): 1796. http://dx.doi.org/10.3390/life12111796.
Повний текст джерелаАнотація:
Psoriasis is associated with accelerated rates of cardiovascular disease (CVD). Laser Speckle Contrast Imaging (LSCI) is a novel, non-interventional technique for the dynamic assessment of microvascular endothelial dysfunction, which represents an early precursor of CVD. We investigated whether skin microvascular reactivity is impaired in psoriasis and whether an association exists with large artery stiffening. Skin microvascular reactivity was assessed with LSCI combined with post-occlusive reactive hyperaemia protocol in psoriasis patients and controls in the absence of established CVD. Arterial stiffness and central hemodynamics were assessed throughout a whole 24 h period with the Mobil-O-Graph device. Most LSCI indices of microvascular reactivity were impaired in psoriasis patients (n = 90) compared to controls (n = 45) [baseline flux; occlusion flux; peak-to-baseline magnitude; baseline cutaneous vascular conductance (CVC); percentage increase in CVC, p < 0.001 for all comparisons]. In multivariate analysis, psoriatic disease predicted the above markers independently of classical CVD risk factors. Augmentation index, peripheral pulse pressure, and central systolic/diastolic blood pressure correlated with LSCI microvascular responses in the study population (n = 135). Pulse wave velocity significantly correlated with nearly all LSCI parameters, while the association with baseline flux was independent of CVD risk factors and psoriatic disease in multivariate analysis (beta = 0.096, p = 0.039). This study provides evidence of altered skin microvascular responses in psoriasis by use of LSCI, and interaction with macrovascular dysfunction, before the establishment of overt CVD. A non-interventional approach of skin microcirculation with LSCI might be used as an early indicator of vascular health in psoriasis.
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Cooper, Laura, Rodney K. Chan, Phillip Kemp Bohan, Anders H. Carlsson, and Tyler Everett. "642 The Use of Laser Speckle Contrast Imaging in Assessing Depth and Progression of Burn Wounds." Journal of Burn Care & Research 41, Supplement_1 (March 2020): S166—S167. http://dx.doi.org/10.1093/jbcr/iraa024.262.
Повний текст джерелаАнотація:
Abstract Introduction The ability of laser speckle contrast imaging (LSCI) to provide real-time images of blood flow makes this modality appealing in the assessment of burn wounds, particularly for clinicians making treatment decisions based on burn wound depth and presumed progression. Here we present 2 preclinical studies that used LSCI to assess wound progress, both immediately and months after injury. Methods LSCI images were taken 10-40cm away from the wound and captured with a 1388x1038-pixel CCD camera. In the first study, LSCI images were captured prior to and immediately following creation of superficial partial-thickness (SPTB, 10s), deep partial-thickness (DPTB, 15s), and full-thickness burns (FTB, 20s), and on post-burn day (PBD) 1, 2, and 3. In the second study, LSCI images were obtained before and after DPTB creation and on PBD 7, 14, 21, 28, 60, 90, and 120. Results 92 wounds from 9 swine were included. Speckle data was normalized to control sites and converted to percentages ([speckle wound/speckle control] x 100), producing speckle percentage of control (SPOC) which quantifies the relative decrease or increase in speckle output (vascularity). SPOC was significantly decreased for all burn times on PBD 0, 1, and 2. By PBD 3, only DPTB and FTB remained diminished (p=0.028 and p=0.005, respectively), and FTB SPOC was significantly less than the SPTB (p=0.015). In the second study, SPOC showed an increase post-debridement on PBD 7, noted as post-debridement day (PDD) 0. SPOC continued to increase significantly to a peak at PDD 7 (p< 0.0001) and remained elevated until PDD 28. By PDD 60, SPOC was no longer significantly increased. Conclusions LSCI is a reliable method for analyzing burn depth and wound progression in the preclinical setting. LSCI data shows an immediate decrease in vascularity at all burn depths immediately following burn creation, followed by a peak in vascularity on PDD 7, with a trend back to normal by PDD 60. Applicability of Research to Practice The correlation of wound bed vascularity based on LSCI to known data on burn depth and progression suggests that LSCI could be a useful measurement tool in the clinical setting for the provider determining wound viability.
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Mennes, Onno A., Jaap J. van Netten, Jeff G. van Baal, Riemer H. J. A. Slart, and Wiendelt Steenbergen. "The Association between Foot and Ulcer Microcirculation Measured with Laser Speckle Contrast Imaging and Healing of Diabetic Foot Ulcers." Journal of Clinical Medicine 10, no. 17 (August 27, 2021): 3844. http://dx.doi.org/10.3390/jcm10173844.
Повний текст джерелаАнотація:
Diagnosis of peripheral artery disease in people with diabetes and a foot ulcer using current non-invasive blood pressure measurements is challenging. Laser speckle contrast imaging (LSCI) is a promising non-invasive technique to measure cutaneous microcirculation. This study investigated the association between microcirculation (measured with both LSCI and non-invasive blood pressure measurement) and healing of diabetic foot ulcers 12 and 26 weeks after measurement. We included sixty-one patients with a diabetic foot ulcer in this prospective, single-center, observational cohort-study. LSCI scans of the foot, ulcer, and ulcer edge were conducted, during baseline and post-occlusion hyperemia. Non-invasive blood pressure measurement included arm, foot, and toe pressures and associated indices. Healing was defined as complete re-epithelialization and scored at 12 and 26 weeks. We found no significant difference between patients with healed or non-healed foot ulcers for both types of measurements (p = 0.135–0.989). ROC curves demonstrated moderate sensitivity (range of 0.636–0.971) and specificity (range of 0.464–0.889), for LSCI and non-invasive blood pressure measurements. Therefore, no association between diabetic foot ulcer healing and LSCI-measured microcirculation or non-invasive blood pressure measurements was found. The healing tendency of diabetic foot ulcers is difficult to predict based on single measurements using current blood pressure measurements or LSCI.
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Mennes, Onno A., Mark Selles, Jaap J. van Netten, Jeff G. van Baal, Wiendelt Steenbergen, and Riemer H. J. A. Slart. "Semi-Automatic Tracking of Laser Speckle Contrast Images of Microcirculation in Diabetic Foot Ulcers." Diagnostics 10, no. 12 (December 6, 2020): 1054. http://dx.doi.org/10.3390/diagnostics10121054.
Повний текст джерелаАнотація:
Foot ulcers are a severe complication of diabetes mellitus. Assessment of the vascular status of diabetic foot ulcers with Laser Speckle Contrast Imaging (LSCI) is a promising approach for diagnosis and prognosis. However, manual assessment during analysis of LSCI limits clinical applicability. Our aim was to develop and validate a fast and robust tracking algorithm for semi-automatic analysis of LSCI data. The feet of 33 participants with diabetic foot ulcers were recorded with LSCI, including at baseline, during the Post-Occlusive Reactive Hyperemia (PORH) test, and during the Buerger’s test. Different regions of interest (ROIs) were used to measure microcirculation in different areas of the foot. A tracking algorithm was developed in MATLAB to reposition the ROIs in the LSCI scans. Manual- and algorithm-tracking of all recordings were compared by calculating the Intraclass Correlation Coefficient (ICC). The algorithm was faster in comparison with the manual approach (90 s vs. 15 min). Agreement between manual- and algorithm-tracking was good to excellent during baseline (ICC = 0.896–0.984; p < 0.001), the PORH test (ICC = 0.790–0.960; p < 0.001), and the Buerger’s test (ICC = 0.851–0.978; p < 0.001), resulting in a tracking algorithm that delivers assessment of LSCI in diabetic foot ulcers with results comparable to a labor-intensive manual approach, but with a 10-fold workload reduction.
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Ramchandra, Rohit, Carolyn J. Barrett, Sarah-Jane Guild, and Simon C. Malpas. "Evidence of differential control of renal and lumbar sympathetic nerve activity in conscious rabbits." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 290, no. 3 (March 2006): R701—R708. http://dx.doi.org/10.1152/ajpregu.00504.2005.
Повний текст джерелаАнотація:
We have explored the possibility that renal sympathetic nerve activity (RSNA) and vasomotor sympathetic nerve activity are differentially regulated. We measured sympathetic nerve activity (SNA) to the kidney and the hind limb vasculature in seven conscious rabbits 6–8 days after the implantation of recording electrodes. Acute infusion of NG-nitro-l-arginine methyl ester (l-NAME) (6 mg·kg−1·min−1 for 5 min) led to an increase in blood pressure (from 66 ± 1 to 82 ± 3 mmHg) and a decrease in heart rate (from 214 ± 15 to 160 ± 13 bpm). l-NAME administration caused a significantly greater decrease in RSNA than lumbar sympathetic nerve activity (LSNA) (to 68 ± 14% vs. 84 ± 4% of control values, respectively). Volume expansion (1.5 ml·kg−1·min−1) resulted in a significant decrease in RSNA to 66 ± 7% of control levels but no change in LSNA (127 ± 20%). There was no difference in the gain of the baroreflex curves between the LSNA and RSNA [maximum gain of −7.6 ± 0.4 normalized units (nu)/mmHg for LSNA vs. −7.9 ± 0.75 nu/mmHg for RSNA]. A hypoxic stimulus (10% O2 and 3% CO2) led to identical increases in both RSNA and LSNA (195 ± 40% and 158 ± 21% of control values, respectively). Our results indicate tailored differential control of RSNA and LSNA in response to acute stimuli.
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Ford, Renee, Huiqing Lu, Zhengbo Duanmu, Tadeusz Scislo, and Joseph C. Dunbar. "The Effect of the Removal of the Area Postrema on Insulin and IGF-1-Induced Cardiovascular and Sympathetic Nervous Responses." International Journal of Experimental Diabetes Research 1, no. 1 (2000): 59–67. http://dx.doi.org/10.1155/edr.2000.59.
Повний текст джерелаАнотація:
Previous studies have demonstrated that insulin and IGF-1 both increase lumbar sympathetic nerve activity (LSNA) and decrease mean arterial pressure (MAP). We hypothesized that the peripheral responses to insulin and IGF-1 are mediated, at least in part,viathe central nervous system. In this study we determined the effects of the peripheral administration of both insulin and IGF-1 on cardiovascular dynamics and LSNA following removal of the area postrema (APX), a major site of blood-brain communication. Insulin infusion in normal rats decreased MAP but increased HR and LSNA. When insulin was infused in APX rats it also decreased the MAP but the MAP recovered rapidly and plateaued at a level equivalent to normals after 40 min. Insulin significantly increased the HR and LSNA in the APX rats compared to normals. However, when hypoglycemia was prevented by glucose infusion, the HR and LSNA responses to insulin in the APX rats were similar to normals. IGF-1 also decreased MAP and to a greater extent in the APX rats compared to normals but the increased LSNA in APX rats was equivalent to normals. The APX rats when compared to normals had a greater sensitivity to insulin-induced hypoglycemia while IGF-1 decreased the plasma glucose to a lesser degree in APX rats. We conclude that insulin and IGF-1 entry into the CNS at leastviathe area postrema does not contribute significantly to the hypotensive response and that the greater depressor response to IGF-1 is likely due to enhanced vascular sensitivity in APX rats. The increased HR and LSNA following insulin were likely mediated by an increased reflexive response to hypoglycemia.
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Wildeboer, Aurelia, Wido Heeman, Arne van der Bilt, Christiaan Hoff, Joost Calon, E. Christiaan Boerma, Mahdi Al-Taher, and Nicole Bouvy. "Laparoscopic Laser Speckle Contrast Imaging Can Visualize Anastomotic Perfusion: A Demonstration in a Porcine Model." Life 12, no. 8 (August 16, 2022): 1251. http://dx.doi.org/10.3390/life12081251.
Повний текст джерелаАнотація:
Background: Intestinal resection causes inevitable vascular damage, which cannot always be seen during an intraoperative clinical assessment of local intestinal perfusion. If left unaltered, impaired perfusion can lead to complications, such as anastomotic leakage (AL). Therefore, we demonstrate the use of a novel laparoscopic laser speckle contrast imaging (LSCI)-based approach in order to assess local intestinal perfusion during the construction of intestinal anastomoses. Methods: Three segments were isolated from the small intestine of a pig, while the perfusion of each was compromised by coagulating 7–8 mesenteric arteries. Both clinical assessments and LSCI were used to detect the induced perfusion deficits and to subsequently guide a transection in either a well perfused, marginally perfused, or poorly perfused tissue area within the segment. Bowel ends were then utilized for the creation of three differently perfused anastomoses: well perfused/well perfused (anastomosis segment 1), well perfused/poorly perfused (anastomosis segment 2), and poorly perfused/poorly perfused (anastomosis segment 3). After construction of the anastomoses, a final perfusion assessment using both clinical assessment and LSCI was executed in order to evaluate the vascular viability of the anastomosis. Results: Laparoscopic LSCI enabled continuous assessment of local intestinal perfusion and allowed for detection of perfusion deficits in real time. The imaging feedback precisely guided the surgical procedure, and, when evaluating the final anastomotic perfusion, LSCI was able to visualize the varying degrees of perfusion, whereas standard clinical assessment yielded only minor differences in visual appearance of the tissue. Conclusions: In this technical note, we demonstrate a novel LSCI-based approach for intraoperative perfusion assessment. With its ability to continuously visualize perfusion in real time, laparoscopic LSCI has significant potential for the optimization of anastomotic surgery in the near future.
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Koba, Satoshi, Zhaohui Gao, Jihong Xing, Lawrence I. Sinoway, and Jianhua Li. "Sympathetic responses to exercise in myocardial infarction rats: a role of central command." American Journal of Physiology-Heart and Circulatory Physiology 291, no. 6 (December 2006): H2735—H2742. http://dx.doi.org/10.1152/ajpheart.00522.2006.
Повний текст джерелаАнотація:
In congestive heart failure (CHF), exaggerated sympathetic activation is observed during exercise, which elicits excess peripheral vasoconstriction. The mechanisms causing this abnormality are not fully understood. Central command is a central neural process that induces parallel activation of motor and cardiovascular systems. This study was undertaken to determine whether central command serves as a mechanism that contributes to the exaggerated sympathetic response to exercise in CHF. In decerebrated rats, renal and lumbar sympathetic nerve responses (RSNA and LSNA, respectively) to 30 s of fictive locomotion were examined. The fictive locomotion was induced by electrical stimulation of the mesencephalic locomotor region (MLR). The study was performed in control animals (fractional shortening > 40%) and animals with myocardial infarctions (MI; fractional shortening < 30%). With low stimulation of the MLR (current intensity = 20 μA), the sympathetic responses were not significantly different in the control (RSNA: +18 ± 4%; LSNA: +3 ± 2%) and MI rats (RSNA: +16 ± 5%; LSNA: +8 ± 3%). With intense stimulation of the MLR (50 μA), the responses were significantly greater in MI rats (RSNA: +127 ± 15%; LSNA: +57 ± 10%) than in the control rats (RSNA: +62 ± 5%; LSNA: +21 ± 6%). In this study, the data demonstrate that RSNA and LSNA responses to intense stimulation of the MLR are exaggerated in MI rats. We suggest that intense activation of central command may play a role in evoking exaggerated sympathetic activation and inducing excessive peripheral vasoconstriction during exercise in CHF.
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Sun, Guanghao, Yanbin Sun, Zifang Zou, and Shun Xu. "Analysis of Segmental Lymph Node Metastasis and Clinical Features in cT1N0M0 Lung Adenocarcinoma." BioMed Research International 2020 (February 18, 2020): 1–7. http://dx.doi.org/10.1155/2020/2842604.
Повний текст джерелаАнотація:
The progression of lung adenocarcinoma through lymph node metastasis has been well established; however, the process of segmental lymph node (LSN) metastasis in cT1N0M0 lung adenocarcinoma remains unclear. We aimed to elucidate the markers of lymph node metastasis to different segments in early-stage lung adenocarcinoma and identify new indications for segmentectomy. A total of 200 patients were enrolled in this study. These patients were diagnosed with cT1N0M0 lung adenocarcinoma after positron emission tomography/computed tomography and received lobectomy and lymph node dissection surgeries. Lymph nodes retrieved from each station were sorted. The metastatic status of the isolated (i) LSNs and several characteristics were analyzed. Patients with ground-glass nodules (GGNs) (P=0.025), AIS/MIA/lepidic adenocarcinoma (P=0.038), nodules with a maximum diameter ≤1 cm (P=0.017), maximum standardized uptake value (SUVmax) < 2.5 (P=0.029), serum carcinoembryonic antigen (CEA) levels ≤4.5 ng/ml (P=0.036), and no N1 lymph nodes metastasis (P=0.036) had significantly lower iLSN metastasis rates than those without these characteristics. Pure GGNs, CEA levels ≤4.5 ng/ml, SUVmax < 2.5, tumors with a maximum diameter of ≤1 cm, or those confirmed to be adenocarcinoma in situ, minimally invasive adenocarcinoma, or invasive lepidic-predominant adenocarcinoma by frozen section may indicate segmentectomy. However, segmentectomy is not suitable for patients with metastasis to the N1 lymph nodes.
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Khashru, Muhsin B. B., Zeng T. Wang, and Bilkis Akthar. "The use of laser speckle contrast imaging in clinical applications." International Journal of Scientific Reports 6, no. 5 (April 21, 2020): 193. http://dx.doi.org/10.18203/issn.2454-2156.intjscirep20201557.
Повний текст джерелаАнотація:
<p class="abstract">Laser speckle contrast imaging (LSCI) is a useful device which is recruited for visualizing full-field microcirculatory images. The speckle pattern is produced as a consistent light illuminates a rough object, and the backscattered radiation is transformed into images and be shown on a screen. Movement within the object results in the fluctuation of patterns over time. Similar information can be attained by employing the Doppler effect, which needs to be scanned again. However, LSCI renders similar data without any further scanning procedure. Nowadays, LSCI has gained expanded consideration, in part because of its accelerated adoption for blood flow studies in the different surgical departments. Here we represent and review the application of LSCI methods of visualizing the field of microcirculation as medical applications from different clinical aspects and discuss the drawbacks that hinder its approval clinically.</p>
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Xu, L., and V. L. Brooks. "ANG II chronically supports renal and lumbar sympathetic activity in sodium-deprived, conscious rats." American Journal of Physiology-Heart and Circulatory Physiology 271, no. 6 (December 1, 1996): H2591—H2598. http://dx.doi.org/10.1152/ajpheart.1996.271.6.h2591.
Повний текст джерелаАнотація:
The hypothesis that chronic elevations in endogenous angiotensin II (ANG II) increase sympathetic outflow in conscious, normotensive rats was tested by determining if acute blockade of ANG II receptors with losartan (10 mg/kg iv) decreases renal sympathetic nerve activity (RSNA), lumbar sympathetic nerve activity (LSNA), or heart rate (HR) more in rats with higher ANG II levels due to a low sodium (LS) diet compared with a control sodium (CS) or high sodium (HS) diet. In LS rats, losartan decreased (P < 0.05) mean arterial pressure (MAP) in two phases: an immediate decrease of 23 +/- 2 mmHg and a slower fall to 35 +/- 4 mmHg below control 40 min postlosartan. Five minutes after losartan, RSNA (149 +/- 13%), LSNA (143 +/- 5%), and HR (109 +/- 2%) were increased (P < 0.05). Despite further falls in MAP, the elevation in RSNA and HR remained constant, and LSNA decreased toward control (119 +/- 4%). After restoration of MAP to basal levels with methoxamine or phenylephrine infusion, RSNA (46 +/- 8%), LSNA (49 +/- 11%), and HR (76 +/- 2%) were suppressed (P < 0.05). In CS rats, losartan also initially decreased (P < 0.05) MAP by 6 +/- 2 mmHg and increased (P < 0.05) RSNA to 129 +/- 13%. When MAP was returned to control, RSNA was decreased (70 +/- 8%; P < 0.05) but less than in LS rats. In contrast, no changes in MAP, RSNA, LSNA, or HR were observed after losartan in HS rats. In conclusion, endogenous ANG II chronically supports RSNA, LSNA, and HR in conscious, normotensive low and normal sodium intake rats.
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Mueller, Patrick J. "Exercise training attenuates increases in lumbar sympathetic nerve activity produced by stimulation of the rostral ventrolateral medulla." Journal of Applied Physiology 102, no. 2 (February 2007): 803–13. http://dx.doi.org/10.1152/japplphysiol.00498.2006.
Повний текст джерелаАнотація:
Exercise training (ExTr) has been associated with blunted activation of the sympathetic nervous system in several animal models and in some human studies. Although these data are consistent with the hypothesis that ExTr reduces the incidence of cardiovascular diseases via reduced sympathoexcitation, the mechanisms are unknown. The rostral ventrolateral medulla (RVLM) is important in control of sympathetic nervous system activity in both physiological and pathophysiological states. The purpose of the present study was to test the hypothesis that ExTr results in reduced sympathoexcitation mediated at the level of the RVLM. Male Sprague-Dawley rats were treadmill trained or remained sedentary for 8–10 wk. RVLM microinjections were performed under Inactin anesthesia while mean arterial pressure, heart rate, and lumbar sympathetic nerve activity (LSNA) were recorded. Bilateral microinjections of the GABAA antagonist bicuculline (5 mM, 90 nl) into the RVLM increased LSNA in sedentary animals (169 ± 33%), which was blunted in ExTr animals (100 ± 22%, P < 0.05). Activation of the RVLM with unilateral microinjections of glutamate (10 mM, 30 nl) increased LSNA in sedentary animals (76 ± 13%), which was also attenuated by training (26 ± 2%, P < 0.05). Bilateral microinjections of the ionotropic glutamate receptor antagonist kynurenate (40 mM, 90 nl) produced small increases in mean arterial pressure and LSNA that were similar between groups. Results suggest that ExTr may reduce increases in LSNA due to reduced activation of the RVLM. Conversely, we speculate that the relatively enhanced activation of LSNA in sedentary animals may be related to the increased incidence of cardiovascular disease associated with a sedentary lifestyle.
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Koba, Satoshi, Jihong Xing, Lawrence I. Sinoway, and Jianhua Li. "Sympathetic nerve responses to muscle contraction and stretch in ischemic heart failure." American Journal of Physiology-Heart and Circulatory Physiology 294, no. 1 (January 2008): H311—H321. http://dx.doi.org/10.1152/ajpheart.00835.2007.
Повний текст джерелаАнотація:
Congestive heart failure (CHF) induces abnormal regulation of peripheral blood flow during exercise. Previous studies have suggested that a reflex from contracting muscle is disordered in this disease. However, there has been very little investigation of the muscle reflex regulating sympathetic outflows in CHF. Myocardial infarction (MI) was induced by the coronary artery ligation in rats. Echocardiography was performed to determine fractional shortening (FS), an index of the left ventricular function. We examined renal and lumbar sympathetic nerve activities (RSNA and LSNA, respectively) during 1-min repetitive (1- to 4-s stimulation to relaxation) contraction or stretch of the triceps surae muscles. During these interventions, the RSNA and LSNA responded synchronously as tension was developed. The RSNA and LSNA responses to contraction were significantly greater in MI rats ( n = 13) with FS <30% than in control animals ( n = 13) with FS >40% (RSNA: +49 ± 7 vs. +19 ± 4 a.u., P < 0.01; LSNA: +28 ± 7 vs. +8 ± 2 a.u., P < 0.01) at the same tension development. Stretch also increased the RSNA and LSNA to a larger degree in MI ( n = 13) than in control animals ( n = 13) (RSNA: +36 ± 6 vs. +19 ± 3 a.u., P < 0.05; LSNA: +24 ± 3 vs. +9 ± 2 a.u., P < 0.01). The data demonstrate that CHF exaggerates sympathetic nerve responses to muscle contraction as well as stretch. We suggest that muscle afferent-mediated sympathetic outflows contribute to the abnormal regulation of peripheral blood flow seen during exercise in CHF.
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Ambrus, Rikard, Rune B. Strandby, Lars Bo Svendsen, Michael P. Achiam, John F. Steffensen, and Morten Bo Søndergaard Svendsen. "Laser Speckle Contrast Imaging for Monitoring Changes in Microvascular Blood Flow." European Surgical Research 56, no. 3-4 (2016): 87–96. http://dx.doi.org/10.1159/000442790.
Повний текст джерелаАнотація:
Background/Aims: Microvascular blood flow is essential for healing and predicts surgical outcome. The aim of the current study was to investigate the relation between fluxes measured with the laser speckle contrast imaging (LSCI) technique and changes in absolute blood flow. In addition, we studied the reproducibility of the LSCI technique when assessing the intra-abdominal microcirculation of the pig. Methods: During trial 1, a fish gill arch was mechanically perfused with heparinized fish blood under controlled stepwise-altered flow rates alongside mechanically induced movement artefacts. The microcirculation of the fish gill was simultaneously assessed with the LSCI technique. In trial 2, microcirculation was measured in the stomach, liver, and small intestine of 10 pigs by two observers. Results: A linear correlation was observed between flux and volumetric flow. During conditions of no volumetric flow, the high recording speed with the LSCI technique registered the movement artefacts as flow signals. The LSCI measurements showed good correlation and agreement between the two observers when assessing microcirculation in the stomach, liver, and small intestine (r2 = 0.857, 0.956, and 0.946; coefficients of variation = 6.0, 3.2, and 6.4%, respectively). Conclusion: Due to the non-contact and real-time assessment over large areas, LSCI is a promising technique for the intraoperative assessment of intra-abdominal microcirculation. A linear correlation between flux and volumetric flow was found, in accordance with previous experimental studies. However, movement artefacts affect flux measurements, and the choice of the sampling speed must be made with care, depending on the given setting.
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Scrogin, Karie E., Eugene T. Grygielko, and Virginia L. Brooks. "Osmolality: a physiological long-term regulator of lumbar sympathetic nerve activity and arterial pressure." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 276, no. 6 (June 1, 1999): R1579—R1586. http://dx.doi.org/10.1152/ajpregu.1999.276.6.r1579.
Повний текст джерелаАнотація:
Acute infusion of hypertonic fluid increases mean arterial pressure (MAP) in part by elevating nonrenal sympathetic activity. However, it is not known whether chronic, physiological increases in osmolality also increase sympathetic activity. To test this hypothesis, MAP, heart rate (HR), and lumbar sympathetic nerve activity (LSNA) were measured in conscious, 48-h water-deprived rats (WD) during a progressive reduction in osmolality produced by a 2-h systemic infusion (0.12 ml/min) of 5% dextrose in water (5DW). Water deprivation significantly increased osmolality (308 ± 2 vs. 290 ± 2 mosmol/kgH2O, P < 0.001), HR (453 ± 7 vs. 421 ± 10 beats/min, P < 0.05), and LSNA (63.5 ± 1.8 vs. 51.9 ± 3.8% baroreflex maximum, P < 0.01). Two hours of 5DW infusion reduced osmolality (−15 ± 5 mosmol/kgH2O), LSNA (−23 ± 3% baseline), and MAP (−10 ± 1 mmHg). To evaluate the role of vasopressin in these changes, rats were pretreated with a V1-vasopressin receptor antagonist. The antagonist lowered MAP (−5 ± 1 mmHg) and elevated HR (32 ± 7 beats/min) and LSNA (11 ± 3% baseline) in WD ( P < 0.05), but not in water-replete, rats. 5DW infusion had a similar cumulative effect on all variables in V1-blocked WD rats, but had no effect in water-replete rats. Infusion of the same volume of normal saline in WD rats did not change osmolality, LSNA or MAP. Together these data indicate that, in dehydrated rats, vasopressin supports MAP and suppresses LSNA and HR and that physiological changes in osmolality directly influence sympathetic activity and blood pressure independently of changes in vasopressin and blood volume.
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Sohrabi, M., P. Mahzari, S. A. Farzaneh, J. R. Mills, P. Tsolis, and S. Ireland. "Novel Insights Into Mechanisms of Oil Recovery by Use of Low-Salinity-Water Injection." SPE Journal 22, no. 02 (September 1, 2016): 407–16. http://dx.doi.org/10.2118/172778-pa.
Повний текст джерелаАнотація:
Summary The underlying mechanism of oil recovery by low-salinity-water injection (LSWI) is still unknown. It would, therefore, be difficult to predict the performance of reservoirs under LSWI. A number of mechanisms have been proposed in the literature, but these are controversial and have largely ignored crucial fluid/fluid interactions. Our direct-flow-visualization investigations (Emadi and Sohrabi 2013) have revealed that a physical phenomenon takes place when certain crude oils are contacted by low-salinity water, leading to a spontaneous formation of micelles that can be seen in the form of microdispersions in the oil phase. In this paper, we present the results of a comprehensive study that includes experiments at different scales designed to systematically investigate the role of the observed crude-oil/brine interaction and micelle formation in the process of oil recovery by LSWI. The experiments include direct-flow (micromodel) visualization, crude-oil characterization, coreflooding, and spontaneous-imbibition experiments. We establish a clear link between the formation of these micelles, the natural surface-active components of crude oil, and the improvement in oil recovery because of LSWI. We present the results of a series of spontaneous- and forced-imbibition experiments carefully designed with reservoir cores to investigate the role of the microdispersions in wettability alteration and oil recovery. To further assess the significance of this mechanism, in a separate exercise, we eliminate the effect of clay by performing an LSWI experiment in a clay-free core. Absence of clay minerals is expected to significantly reduce the influence of the previously proposed mechanisms for oil recovery by LSWI. Nevertheless, we observe significant additional oil recovery compared with high-salinity-water injection (HSWI) in the clay-free porous medium. The additional oil recovery is attributed to the formation of micelles stemming from the crude-oil/brine-interaction mechanism described in this work and our previous related publications. Compositional analyses of the oil produced during this coreflood experiment indicate that the natural surface-active compounds of the crude oil had been desorbed from the rock surfaces during the LSWI period of the experiment when the additional oil was produced. The results of this study present new insights into the fundamental mechanisms involved in oil recovery by LSWI and new criteria for evaluating the potential of LSWI for application in oil reservoirs. The fluid/fluid interactions revealed in this research can be applied to oil recovery from both sandstone and carbonate oil reservoirs because they are mainly derived from fluid/fluid interactions that control wettability alteration in both sandstone and carbonate rocks.
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Kim, Youngkyu, Woo June Choi, Jungmin Oh, and Jun Ki Kim. "Compact Smartphone-Based Laser Speckle Contrast Imaging Endoscope Device for Point-of-Care Blood Flow Monitoring." Biosensors 12, no. 6 (June 9, 2022): 398. http://dx.doi.org/10.3390/bios12060398.
Повний текст джерелаАнотація:
Laser speckle contrast imaging (LSCI) is a powerful visualization tool for quantifying blood flow in tissues, providing simplicity of configuration, ease of use, and intuitive results. With recent advancements, smartphone and camera technologies are suitable for the development of smartphone-based LSCI applications for point-of-care (POC) diagnosis. A smartphone-based portable LSCI endoscope system was validated for POC diagnosis of vascular disorders. The endoscope consisted of compact LED and laser illumination, imaging optics, and a flexible fiberscope assembled in a 3D-printed hand-held cartridge for access to body cavities and organs. A smartphone’s rear camera was mounted thereto, enabling endoscopy, LSCI image acquisition, and processing. Blood flow imaging was calibrated in a perfused tissue phantom consisting of a microparticle solution pumped at known rates through tissue-mimicking gel and validated in a live rat model of BBN-induced bladder cancer. Raw LSCI images successfully visualized phantom flow: speckle flow index showed linearity with the pump flow rate. In the rat model, healthy and cancerous bladders were distinguishable in structure and vasculature. The smartphone-based low-cost portable mobile endoscope for monitoring blood flow and perfusion shows promise for preclinical applications and may be suitable for primary diagnosis at home or as a cost-effective POC testing assay.
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Richards, Lisa M., SM Shams Kazmi, Katherine E. Olin, James S. Waldron, Douglas J. Fox, and Andrew K. Dunn. "Intraoperative multi-exposure speckle imaging of cerebral blood flow." Journal of Cerebral Blood Flow & Metabolism 37, no. 9 (January 23, 2017): 3097–109. http://dx.doi.org/10.1177/0271678x16686987.
Повний текст джерелаАнотація:
Multiple studies have demonstrated that laser speckle contrast imaging (LSCI) has high potential to be a valuable cerebral blood flow monitoring technique during neurosurgery. However, the quantitative accuracy and sensitivity of LSCI is limited, and highly dependent on the exposure time. An extension to LSCI called multi-exposure speckle imaging (MESI) overcomes these limitations, and was evaluated intraoperatively in patients undergoing brain tumor resection. This clinical study ( n = 8) recorded multiple exposure times from the same cortical tissue area spanning 0.5–20 ms, and evaluated images individually as single-exposure LSCI and jointly using the MESI model. This study demonstrated that the MESI estimates provided the broadest flow sensitivity for sampling the flow magnitude in the human brain, closely followed by the shorter exposure times. Conservation of flow analysis on vascular bifurcations was used to validate physiological accuracy, with highly conserved flow estimates (<10%) from both MESI and 1 ms LSCI ( n = 14 branches). The MESI model had high goodness-of-fit with proper image calibration and acquisition, and was used to monitor blood flow changes after tissue cautery. Results from this study demonstrate that intraoperative MESI can be performed with high quantitative accuracy and sensitivity for cerebral blood flow monitoring.
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Guyenet, P. G., R. A. Darnall, and T. A. Riley. "Rostral ventrolateral medulla and sympathorespiratory integration in rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 259, no. 5 (November 1, 1990): R1063—R1074. http://dx.doi.org/10.1152/ajpregu.1990.259.5.r1063.
Повний текст джерелаАнотація:
The respiratory modulation of the lumbar sympathetic nerve discharge (LSND) was examined in halothane-anesthetized, paralyzed, and vagotomized rats by means of phrenic nerve discharge (PND)-triggered histograms. The respiratory modulation was 1) proportional to PND amplitude during chemoreceptor activation with CO2 and 2) reduced at elevated arterial pressure. Bilateral injections of bicuculline [gamma-aminobutyric acid (GABA)A receptor antagonist, n = 5] into the rostral ventrolateral medulla (RVLM), but not into medullary raphe, reversibly increased mean arterial pressure (MAP) and resting LSND, decreased the baroreflex, reduced PND amplitude and central respiratory rate, and greatly magnified the respiratory modulation of LSND. Injections of strychnine (glycine receptor antagonist, n = 5) or phaclofen (GABAB receptor antagonist, n = 2) into RVLM were without effect. Injections of kynurenic acid (excitatory amino acid receptor antagonist) into RVLM (n = 8), but not raphe (n = 3), reduced PND amplitude, increased central respiratory rate, reduced MAP, elevated resting LSND slightly, and greatly reduced the respiratory modulation of LSND. These data suggest that the rostral tip of the ventrolateral medulla represents a critical link between the central respiratory rhythm generator and the vasomotor outflow. Also, it indicates that the respiratory modulation of SND does not involve a gating of the activity of the medullary neurons that convey baroreceptor information to RVLM sympathoexcitatory neurons.
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Brooks, Virginia L., Yue Qi, and Theresa L. O'Donaughy. "Increased osmolality of conscious water-deprived rats supports arterial pressure and sympathetic activity via a brain action." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, no. 5 (May 2005): R1248—R1255. http://dx.doi.org/10.1152/ajpregu.00638.2004.
Повний текст джерелаАнотація:
To test the hypothesis that high osmolality acts in the brain to chronically support mean arterial pressure (MAP) and lumbar sympathetic nerve activity (LSNA), the osmolality of blood perfusing the brain was reduced in conscious water-deprived and water-replete rats by infusion of hypotonic fluid via bilateral nonoccluding intracarotid catheters. In water-deprived rats, the intracarotid hypotonic infusion, estimated to lower osmolality by ∼2%, decreased MAP by 9 ± 1 mmHg and LSNA to 86 ± 7% of control; heart increased by 25 ± 8 beats per minute (bpm) (all P < 0.05). MAP, LSNA, and heart rate did not change when the hypotonic fluid was infused intravenously. The intracarotid hypotonic fluid infusion was also ineffective in water-replete rats. Prior treatment with a V1 vasopressin antagonist did not alter the subsequent hypotensive and tachycardic effects of intracarotid hypotonic fluid infusion in water-deprived rats. In summary, acute decreases in osmolality of the carotid blood of water-deprived, but not water-replete, rats decreases MAP and LSNA and increases heart rate. These data support the hypothesis that the elevated osmolality induced by water deprivation acts via a region perfused by the carotid arteries, presumably the brain, to tonically increase MAP and LSNA and suppress heart rate.
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Kazmi, Syed Mohammad Shams, Ashwin B. Parthasarthy, Nelly E. Song, Theresa A. Jones, and Andrew K. Dunn. "Chronic Imaging of Cortical Blood Flow using Multi-Exposure Speckle Imaging." Journal of Cerebral Blood Flow & Metabolism 33, no. 6 (April 10, 2013): 798–808. http://dx.doi.org/10.1038/jcbfm.2013.57.
Повний текст джерелаАнотація:
Chronic imaging of cerebral blood flow (CBF) is an important tool for investigating vascular remodeling after injury such as stroke. Although techniques such as Laser Speckle Contrast Imaging (LSCI) have emerged as valuable tools for imaging CBF in acute experiments, their utility for chronic measurements or cross-animal comparisons has been limited. Recently, an extension to LSCI called Multi-Exposure Speckle Imaging (MESI) was introduced that increases the quantitative accuracy of CBF images. In this paper, we show that estimates of chronic blood flow are better with MESI than with traditional LSCI. We evaluate the accuracy of the MESI flow estimates using red blood cell (RBC) photographic tracking as an absolute flow calibration in mice over several days. The flow measures computed using the MESI and LSCI techniques were found to be on average 10% and 24% deviant ( n = 9 mice), respectively, compared with RBC velocity changes. We also map CBF dynamics after photo-thrombosis of selected cortical microvasculature. Correlations of flow dynamics with RBC tracking were closer with MESI ( r = 0.88) than with LSCI ( r = 0.65) up to 2 weeks from baseline. With the increased quantitative accuracy, MESI can provide a platform for studying the efficacy of stroke therapies aimed at flow restoration.
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Sharabi, F. M., G. B. Guo, F. M. Abboud, M. D. Thames, and P. G. Schmid. "Contrasting effects of vasopressin on baroreflex inhibition of lumbar sympathetic nerve activity." American Journal of Physiology-Heart and Circulatory Physiology 249, no. 5 (November 1, 1985): H922—H928. http://dx.doi.org/10.1152/ajpheart.1985.249.5.h922.
Повний текст джерелаАнотація:
Baroreflex inhibition of lumbar sympathetic nerve activity (LSNA) during intravenous infusions of phenylephrine and vasopressin is contrasted in rats and rabbits. In rabbits, vasopressin caused smaller increases in arterial pressure and greater inhibition of LSNA than phenylephrine. In Sprague-Dawley rats, however, both vasopressin and phenylephrine caused equivalent increases in arterial pressure and reflex reductions in LSNA. The inhibition of LSNA was mediated through the arterial baroreceptors in both species because it was abolished by sinoaortic denervation. In rats, the possibility that a high level of endogenous vasopressin may have prevented the demonstration of a facilitated baroreflex with the infusion of exogenous vasopressin is unlikely since vasopressin also did not facilitate the reflex in Brattleboro rats, which lack circulating vasopressin. Further, Sprague-Dawley rats were responsive to exogenous vasopressin since infusion of increasing doses of vasopressin caused significant increases in urinary osmolality as well as progressive increments in arterial pressure. The results indicate that intravenous vasopressin given for a period of 6 min facilitates the reflex inhibition of LSNA mediated through arterial baroreceptors in rabbits, but not in rats. Vasopressin given for a period of up to 45 min to rats also fails to facilitate baroreflexes, emphasizing the difference from rabbits. In rabbits, this facilitation appears to involve a central mechanism.
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Cassaglia, Priscila A., Zhigang Shi, and Virginia L. Brooks. "Insulin increases sympathetic nerve activity in part by suppression of tonic inhibitory neuropeptide Y inputs into the paraventricular nucleus in female rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 311, no. 1 (July 1, 2016): R97—R103. http://dx.doi.org/10.1152/ajpregu.00054.2016.
Повний текст джерелаАнотація:
Following binding to receptors in the arcuate nucleus (ArcN), insulin increases sympathetic nerve activity (SNA) and baroreflex control of SNA via a pathway that includes the paraventricular nucleus of the hypothalamus (PVN). Previous studies in males indicate that the sympathoexcitatory response is mediated by α-melanocyte stimulating hormone (α-MSH), which binds to PVN melanocortin type 3/4 receptors (MC3/4R). The present study was conducted in α-chloralose-anesthetized female rats to test the hypothesis that suppression of inhibitory neuropeptide Y (NPY) inputs to the PVN is also involved. In support of this, blockade of PVN NPY Y1 receptors with BIBO 3304 (NPY1x), ArcN insulin nanoinjections, and PVN NPY1x followed by ArcN insulin each increased lumbar SNA (LSNA) and its baroreflex regulation similarly. Moreover, prior PVN injections of NPY blocked the sympathoexcitatory effects of ArcN insulin. Finally, PVN nanoinjections of the MC3/4R inhibitor SHU9119 prevented both the acute (15 min) and longer, more slowly developing (60 min), increases in LSNA in response to ArcN insulin. In conclusion, in females, ArcN insulin increases LSNA, in part, by suppressing tonic PVN NPY inhibition, which unmasks excitatory α-MSH drive of LSNA. Moreover, the steadily increasing rise in LSNA induced by ArcN insulin is also dependent on PVN MC3/4R.