bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors affecting energy cost of running during an ultra-endurance race
Authors: Lazzer Stefano , Taboga Paolo , Salvadego Desy , Rejc Enrico , Simunic Bostjan , Narici Marco , Buglione Antonio , Giovanelli Nicola , Antonutto Guglielmo , Grassi Bruno , Pisot Rado , di Prampero Pietro E. 
Published: November 2013

Summary
Purpose: to investigate: 1) the role of V'O2max, fraction of it (F) and metabolic cost of transport (CoT) in determining performance during an ultra-endurance competition and 2) the effects of the race on several biomechanical and morphological parameters of the lower limbs that are likely to affect CoT. Methods: Eleven runners (age: 29-54 years) participated in an ultra-endurance competition consisting of three running stages of 25, 55 and 13 km on three consecutive days. Anthropometric characteristics, body composition, morphological properties of the gastrocnemius medialis, maximal explosive power of the lower limb and V'O2max were determined before the competition. In addition, biomechanics of running and CoT was determined, before and immediately after each running stage. Results: Performance was directly proportional to V'O2max (r=0.77), and F (r=0.36) and inversely proportional to CoT (r=-0.30). Low CoT values were significantly related to high maximal power of the lower limbs (r=-0.74), vertical stiffness (r=-0.65); and low foot-print index (FPI, r=0.70), step frequency (r=0.62) and external work (r=0.60). About 50% of the increase in CoT during the stages of the competition was accounted for by changes in FPI, which represents a global evaluation of medio-lateral displacement of the foot during the whole stance phase, which in turn are associated with the myotendinous characteristics of the lower limb. Conclusions: lower CoT values were related to greater muscular power and lower FPI, suggesting that a better ankle stability is likely to achieve better performance in ultra endurance running competition.
Thyroid hormone regulates cardiac performance during cold acclimation in Zebrafish (Danio rerio)
Authors: Little Alex G. , Seebacher Frank 
Published: November 2013

SummaryLimitations to oxygen transport reduce aerobic scope and thereby activity at thermal extremes. Oxygen transport in fish is facilitated to a large extent by cardiac function so that climate variability may reduce fitness by constraining the performance of the heart. In zebrafish (Danio rerio), thyroid hormone (TH) regulates skeletal muscle function and metabolism in response to thermal acclimation. Here we aimed to determine whether TH also regulates cardiac function during acclimation. We used propylthiouracil and iopanoic acid to induce hypothyroidism in zebrafish over a 3-week acclimation period to either 18 or 28°C. We found that cold-acclimated fish had higher maximum heart rates and sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) activity than warm acclimated fish. Hypothyroid treatment significantly decreased these responses in the cold acclimated fish, but it did not affect the warm-acclimated fish. TH did not influence SERCA gene transcription, nor did it increase metabolic rate, of isolated whole hearts. To verify that physiological changes following hypothyroid treatment were in fact due to the action of TH, we supplemented hypothyroid fish with 3,5-diiodothryronine (T2) or 3,5,3′-triiodothyronine (T3). Supplementation of hypothyroid fish with T2 or T3 restored heart rates and SERCA activity to control levels. We also show that in zebrafish changes in cardiac output in response to warming are primarily mediated by heart rate, rather than by stroke volume. Thus changes in heart rate are important for the overall aerobic capacity of the fish. In addition to its local effects on heart phenotype, we show that TH increases sympathetic tone on the heart at rest and during maximum exercise. Our findings reveal a new pathway through which fish can mitigate the limiting effects of temperature variability on oxygen transport to maintain aerobic scope and promote thermal tolerance.
Melatonin action in a midbrain vocal-acoustic network
Authors: Feng Ni Y. , Bass Andrew H. 
Published: November 2013

Summary
Melatonin is a well-documented time-keeping hormone that can entrain an individual's physiology and behavior to the day-night cycle, though surprisingly little is known about its influence on the neural basis of social behavior, including vocalization. Male midshipman fish (Porichthys notatus) produce several call types distinguishable by duration and by daily and seasonal cycles in their production. We investigated melatonin's influence on the known nocturnal- and breeding season-dependent increase in excitability of the midshipman's vocal network (VN) that directly patterns natural calls. VN output is readily recorded from the vocal nerve as a "fictive call." Five days of constant light significantly increased stimulus threshold levels for calls electrically evoked from vocally active sites in the medial midbrain, supporting previous findings that light suppresses VN excitability, while 2-iodomelatonin (2-IMel; a melatonin analogue) implantation decreased threshold. 2-IMel also increased fictive call duration evoked from medial sites as well as lateral midbrain sites that produced several-fold longer calls irrespective of photoregime or drug treatment. When stimulus intensity was incrementally increased, 2-IMel increased duration only at lateral sites, suggesting melatonin action is stronger in the lateral midbrain. For animals receiving five days of constant darkness, known to increase VN excitability, systemic injections of either of two mammalian melatonin receptor antagonists increased threshold and decreased duration for calls evoked from medial sites. Our results demonstrate melatonin modulation of vocal network excitability and suggest that social context-dependent call types differing in duration may be determined by neuro-hormonal action within specific regions of a midbrain vocal-acoustic network.
Fast growers sprint slower: effects of food deprivation and re-feeding on sprint swimming performance in individual juvenile European sea bass
Authors: Killen Shaun S. , Marras Stefano , McKenzie David J. 
Published: November 2013

Summary
While many ectothermic species can withstand prolonged fasting without mortality, food-deprivation may have sublethal effects of ecological importance, including reductions in locomotor ability. Little is known about how such changes in performance in individual animals are related either to mass loss during food-deprivation or growth rate during re-feeding. This study followed changes in the maximum sprint swimming performance of individual European sea bass Dicentrarchus labrax throughout 45 days of food-deprivation and 30 days of re-feeding. Maximum sprint speed did not show a significant decline until 45 days of food deprivation. Among individuals, the reduction in sprinting speed at this time was not related to mass loss. After 30 days of re-feeding, mean sprinting speed had recovered to match that of control fish. Among individuals, however, maximum sprinting speed was negatively correlated with growth rate after the resumption of feeding. This suggests that the rapid compensatory growth that occurs during re-feeding after a prolonged fast carries a physiological cost in terms of reduced sprinting capacity, the extent of which shows continuous variation among individuals in relation to growth rate. The long-term repeatability of maximum sprint speed was low when fish were fasted or fed a maintenance ration, but was high among control fish fed to satiation. Fish that had been previously food deprived continued to show low repeatability in sprinting ability even after the initiation of ad libitum feeding, probably stemming from variation in compensatory growth among individuals and its associated negative effects on sprinting ability. Together these results suggest that food limitation can disrupt hierarchies of maximum sprint performance within populations. In the wild, the cumulative effects on locomotor capacity of fasting and re-feeding could lead to variable survival among individuals with different growth trajectories following a period of feed deprivation.
Crystal Structure of 1,3-Dimethylimidazolium Bis(fluorosulfonyl)amide: Unexpectedly High Melting Point Arising from Polydentate Hydrogen Bonding
Authors: Fujii Kozo , Mukai Tomohiro , Nishikawa Keiko 
Published: November 2013

Abstract
1,3-Dimethylimidazolium bis(fluorosulfonyl)amide, [C1mim]FSA, is an ionic liquid with a lower viscosity than the bis(trifluoromethanesulfonyl)amide salt, [C1mim]NTf2, but with a higher melting point. The single-crystal X-ray structure analysis reveals that this is because the [C1mim]FSA crystal has low coordination ion number and three types of highly symmetric polydentate C–H···O hydrogen bonds.
Role of multi-detector computed tomography (MDCT) in management of post percutaneous nephrolithotomy (PCNL) bleeding
Authors: Ganpule Arvind P , Shah Darshan H , Ganpule Sanika A , Sabnis Ravindra B , Rajapurkar Mohan M , Desai Mahesh R 
Published: November 2013

Objective: To evaluate the role of multidetector computerized tomography (MDCT) angiography in post percutaneous nephrolithotomy (PCNL) bleed and compare findings with conventional angiography (CA).Material and methods: We conducted a retrospective analysis of patients who had post PCNL bleeding and subsequently underwent a MDCT angiography followed by CA. We reviewed eight patients, who presented between January 2009 and January 2013. We performed a MDCT angiography on a 16 slice GE bright speed CT scanner. All angiographies were done by using the Digital Subtraction Angiography Suite. The angioembolisation, if required, was conducted by an interventional nephrologist, specializing in therapeutic embolisation.Results: The mean age of the patients was 42±17 years. Mean time of post PCNL bleed presentation was 10.06±7.9 days. Five patients presented with aneurysm and three presented with an AV fistula with pseudoaneurysm. The right renal unit was involved in six cases and the left in two cases. The lower polar segmental artery was involved in six cases and the upper polar artery in two cases. The CA and MDCT findings matched in all cases and the MDCT helped the clinician to assess and embolise the appropriate arterial tree.Conclusion: MDCT is rapid, reproducible and noninvasive. MDCT angiography performed in the setting of post PCNL bleeding provides an accurate assessment of the site and nature of bleeding. The MDCT angiography matched the CA findings in all patients in the present study.
Will the Global Village Fracture Into Tribes? Recommender Systems and Their Effects on Consumer Fragmentation
Authors: Hosanagar Kartik , Fleder Daniel , Lee Dokyun , Buja Andreas 
Published: November 2013

Personalization is becoming ubiquitous on the World Wide Web. Such systems use statistical techniques to infer a customer's preferences and recommend content best suited to him (e.g., “Customers who liked this also liked…”). A debate has emerged as to whether personalization has drawbacks. By making the Web hyperspecific to our interests, does it fragment Internet users, reducing shared experiences and narrowing media consumption? We study whether personalization is in fact fragmenting the online population. Surprisingly, it does not appear to do so in our study. Personalization appears to be a tool that helps users widen their interests, which in turn creates commonality with others. This increase in commonality occurs for two reasons, which we term volume and product-mix effects. The volume effect is that consumers simply consume more after personalized recommendations, increasing the chance of having more items in common. The product-mix effect is that, conditional on volume, consumers buy a more similar mix of products after recommendations.This paper was accepted by Sandra Slaughter, information systems.
Field emission from laser cut CNT fibers and films
Authors: Fairchild Steven B. , Bulmer John S. , Sparkes Martin , Boeckl John , Cahay Marc , Back Tyson , Murray P. Terrence , Gruen Gregg , Lange Matthew , Lockwood Nathaniel P. , Orozco Francisco , O’Neill William , Paukner Catharina , Koziol Krzysztof K. K. 
Published: November 2013

Abstract
Soil respiration in a northeastern US temperate forest: a 22‐year synthesis
Authors: Giasson M.-A. , Ellison A. M. , Bowden R. D. , Crill P. M. , Davidson E. A. , Drake J. E. , Frey S. D. , Hadley J. L. , Lavine M. , Melillo J. M. , Munger J. W. , Nadelhoffer K. J. , Nicoll L. , Ollinger S. V. , Savage K. E. , Steudler P. A. , Tang J. , Varner R. K. , Wofsy S. C. , Foster D. R. , Finzi A. C. 
Published: November 2013

To better understand how forest management, phenology, vegetation type, and actual and simulated climatic change affect seasonal and inter‐annual variations in soil respiration (Rs), we analyzed more than 100,000 individual measurements of soil respiration from 23 studies conducted over 22 years at the Harvard Forest in Petersham, Massachusetts, USA. We also used 24 site‐years of eddy‐covariance measurements from two Harvard Forest sites to examine the relationship between soil and ecosystem respiration (Re).Rs was highly variable at all spatial (respiration collar to forest stand) and temporal (minutes to years) scales of measurement. The response of Rs to experimental manipulations mimicking aspects of global change or aimed at partitioning Rs into component fluxes ranged from −70% to +52%. The response appears to arise from variations in substrate availability induced by changes in the size of soil C pools and of belowground C fluxes or in environmental conditions. In some cases (e.g., logging, warming), the effect of experimental manipulations on Rs was transient, but in other cases the time series were not long enough to rule out long‐term changes in respiration rates. Inter‐annual variations in weather and phenology induced variation among annual Rs estimates of a magnitude similar to that of other drivers of global change (i.e., invasive insects, forest management practices, N deposition). At both eddy‐covariance sites, aboveground respiration dominated Re early in the growing season, whereas belowground respiration dominated later. Unusual aboveground respiration patterns—high apparent rates of respiration during winter and very low rates in mid‐to‐late summer—at the Environmental Measurement Site suggest either bias in Rs and Re estimates caused by differences in the spatial scale of processes influencing fluxes, or that additional research on the hard‐to‐measure fluxes (e.g., wintertime Rs, unaccounted losses of CO2 from eddy covariance sites), daytime and nighttime canopy respiration and its impacts on estimates of Re, and independent measurements of flux partitioning (e.g., aboveground plant respiration, isotopic partitioning) may yield insight into the unusually high and low fluxes. Overall, however, this data‐rich analysis identifies important seasonal and experimental variations in Rs and Re and in the partitioning of Re above‐ vs. belowground.
Safely Exceeding Buckling Loads in Long Horizontal Wells: Case Study in Shale Plays
Authors: Menand S.. , Chen D.C.K.. C.K. 
Published: November 2013

Summary
Drilling operations face several limits that intensify uncertainty and risks. Because of the deeper and/or longer wells, drilling equipment is pushed to its mechanical and endurance limits. The general industry perception is that when drillstrings or casing strings exceed conventional helical-buckling criteria, they cannot be operated safely in the hole because the risk of failure or lockup is too high. However, some theoretical, experimental, and field case studies have shown that tubular may be run in the hole even in a buckling state, within safe limits. This paper shows a case study in long horizontal wells for which helical-buckling load has been exceeded without compromising the success of the operations.
Drilling data from Bakken field in North Dakota have been gathered, analyzed, and compared with an advanced drillstring-mechanics model that enables simultaneous calculation of torque, drag, and buckling. A strong focus has been placed on the comparison between conventional buckling criteria and drillpipe (DP) or tubular bending stresses. Field results supported by drillstring modeling suggest that the helical-buckling load has been exceeded during operation at some locations along the drillstring during slide drilling and liner running but with bending stresses at an acceptable level. However, in rotary drilling, buckling should be avoided because it will create high vibrations. In this case study, the effect of drillstring dynamics is not considered.
Demand Uncertainty and Cost Behavior
Authors: Banker Rajiv D. , Byzalov Dmitri , Plehn-Dujowich Jose M. 
Published: November 2013

ABSTRACT
We investigate analytically and empirically the relationship between demand uncertainty and cost behavior. We argue that with more uncertain demand, unusually high realizations of demand become more likely. Accordingly, firms will choose a higher capacity of fixed inputs when uncertainty increases in order to reduce congestion costs. Higher capacity levels imply a more rigid short-run cost structure with higher fixed and lower variable costs. We formalize this “counterintuitive” argument in a simple analytical model of capacity choice. Following this logic, we hypothesize that firms facing higher demand uncertainty have a more rigid short-run cost structure with higher fixed and lower variable costs. We test this hypothesis for the manufacturing sector using data from Compustat and the NBER-CES Industry Database. Evidence strongly supports our hypothesis for multiple cost categories in both datasets. The results are robust to alternative specifications.
Data Availability: All data used in this study are available from public sources.
Le rôle de l’aspect lexical et de la fréquence des formes dans l’input sur la production des formes du passé par des enfants apprenants du français L2 en début d’acquisition
Authors: Thomas Anita 
Published: November 2013

Résumé : L’objectif de cette étude est d’examiner le rôle de l’aspect lexical et de la fréquence des formes dans l’input dans la production orale des formes du passé par des enfants suédois (âgés de 4 à 9 ans) apprenants du français langue seconde (L2) en immersion. Le rôle de la fréquence dans l’input est souvent négligé dans les études sur l’influence de l’aspect lexical tout comme les caractéristiques spécifiques des verbes le sont dans les études consacrées à l’influence de la fréquence des formes. L’analyse de 21 verbes dans l’input puis dans la production des cinq enfants durant les deux premières années d’exposition au français montre un recoupement entre les deux facteurs. Bien que les enfants produisent la plupart des verbes selon leur aspect lexical, les fréquences type et d’occurrence dans l’input permettent d’expliquer à la fois le marquage correct du passé ainsi que la variation que l’on trouve dans les groupes de verbes étudiés. Les résultats confirment ainsi les prédictions d’une approche basée sur l’usage selon laquelle les apprenants construisent leur grammaire à partir de leur expérience de l’input.
Frequency and predictors of complications in neurological surgery: national trends from 2006 to 2011
Authors: Rolston John D. , Han Seunggu J. , Lau Catherine Y. , Berger Mitchel S. , Parsa Andrew T. 
Published: November 2013

Object
Surgical complications increase the cost of health care worldwide and directly contribute to patient morbidity and mortality. In an effort to mitigate morbidity and incentivize best practices, stakeholders such as health insurers and the US government are linking reimbursement to patient outcomes. In this study the authors analyzed a national database to determine basic metrics of how comorbidities specifically affect the subspecialty of neurosurgery.

Methods
Data on 1,777,035 patients for the years 2006–2011 were acquired from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database. Neurosurgical cases were extracted by querying the data for which the surgical specialty was listed as “neurological surgery.” Univariate statistics were calculated using the chi-square test, and 95% confidence intervals were determined for the resultant risk ratios. A multivariate model was constructed using significant variables from the univariate analysis (p < 0.05) with binary logistic regression.

Results
Over 38,000 neurosurgical cases were analyzed, with complications occurring in 14.3%. Cranial cases were 2.6 times more likely to have complications than spine cases, and African Americans and Asians/Pacific Islanders were also at higher risk. The most frequent complications were bleeding requiring transfusion (4.5% of patients) and reoperation within 30 days of the initial operation (4.3% of patients), followed by failure to wean from mechanical ventilation postoperatively (2.5%). Significant predictors of complications included preoperative stroke, sepsis, blood transfusion, and chronic steroid use.

Conclusions
Understanding the landscape of neurosurgical complications will allow better targeting of the most costly and harmful complications of preventive measures. Data from the ACS NSQIP database provide a starting point for developing paradigms of improved care of neurosurgical patients.
Iliac screw placement in neuromuscular scoliosis using anatomical landmarks and uniplanar anteroposterior fluoroscopic imaging with postoperative CT confirmation
Authors: Gressot Loyola V. , Patel Akash J. , Hwang Steven W. , Fulkerson Daniel H. , Jea Andrew 
Published: November 2013

Object
Neuromuscular scoliosis is a challenging pathology to treat. Surgical correction can involve long fusion constructs extending to the pelvis. The deformity inherent in these patients makes it difficult to obtain adequate lateral intraoperative radiographs for traditional image-guided placement of iliac screws.

Methods
A clinical and radiographic assessment of 14 patients with neuromuscular spinal deformity was conducted. From 2007 to 2013, 12 of these patients (mean age 14.25 years, range 10–20 years) underwent long spinal instrumentation (mean 15 levels, range 10–18 levels) and fusion to the pelvis, and 2 underwent placement of a growing rod construct with iliac screw placement at a single institution. The average length of follow-up was 33.7 months (range 6–64 months). Iliac screws were placed after identifying the posterior superior iliac spine and using only anteroposterior fluoroscopy (view of the inlet of the pelvis), rather than the technique of direct palpation of the sciatic notch. The accuracy of iliac screw placement was assessed with routine postoperative CT.

Results
A total of 12 patients had 24 screws placed as part of a long-segment fusion to the pelvis, and 2 patients had two iliac screws placed as part of a growing rod construct for neuromuscular scoliosis. There were no iliac screw misplacements, and no complications directly related to the technique of iliac screw placement. For cases of definitive fusion (n = 12), the average coronal Cobb angle of patients with neuromuscular spinal deformity measured 62° before surgery and 44.3° immediately after surgery. The average preoperative thoracic kyphosis and lumbar sagittal lordosis measured 37.3° and 60.7°, respectively. Immediately after surgery, the thoracic and lumbar angles measured 30° and 41.1°, respectively. At last follow-up, the average coronal Cobb angle was maintained at 45.1°, and the thoracic and lumbar sagittal angles were maintained at 32.8° and 45.3°, respectively.

Conclusions
A less invasive technique for iliac screw placement can be performed safely with a low likelihood of screw misplacement. This technique offers the biomechanical advantages of iliac fixation without the soft tissue exposure typically needed for safe screw insertion. The technique relies on identification of the posterior superior iliac spine and high quality anteroposterior fluoroscopic imaging for a view of the pelvic inlet.