bluuebunny/crossref_metadata_2025 huggingface dataset:
Coordination and symmetry patterns during the drop vertical jump, 6‐months after first‐time lateral ankle sprain
Authors: Doherty Cailbhe , Bleakley Chris , Hertel Jay , Caulfield Brian , Ryan John , Sweeney Kevin , Patterson Matthew R. , Delahunt Eamonn
Published: May 2015

To evaluate the adaptive movement and motor control patterns of a group with a 6‐month history of first‐time lateral ankle sprain (LAS) injury during a drop vertical jump (DVJ) task. Fifty‐one participants with a 6‐month history of first‐time acute LAS injury and twenty controls performed a DVJ task. 3D kinematic and sagittal plane kinetic profiles were plotted for the lower extremity joints of both limbs for the drop jump (phase 1) and drop landing (phase 2) phases of the DVJ. Inter‐limb symmetry and the rate of impact modulation (RIM) relative to bodyweight (BW) during both phases of the DVJ were also determined. LAS participants displayed bilateral increases in knee flexion and an increase in ankle inversion during phases 1 and 2, respectively. They also displayed reduced ankle plantar flexion on their injured limb during both phases of the DVJ (p < 0.05); increased inter‐limb asymmetry of RIM was noted for both phases of the DVJ, while the moment‐of‐force profile exhibited bilaterally greater hip extensor dominance during phase 1. Participants with a 6‐month history of first‐time LAS display some movement patterns consistent with those observed in chronic ankle instability populations during similar tasks. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1537–1544, 2015.
Declining liver graft quality threatens the future of liver transplantation in the United States
Authors: Orman Eric S. , Mayorga Maria E. , Wheeler Stephanie B. , Townsley Rachel M. , Toro‐Diaz Hector H. , Hayashi Paul H. , Sidney Barritt A.
Published: May 2015

National liver transplantation (LT) volume has declined since 2006, in part because of worsening donor organ quality. Trends that degrade organ quality are expected to continue over the next 2 decades. We used the United Network for Organ Sharing (UNOS) database to inform a 20‐year discrete event simulation estimating LT volume from 2010 to 2030. Data to inform the model were obtained from deceased organ donors between 2000 and 2009. If donor liver utilization practices remain constant, utilization will fall from 78% to 44% by 2030, resulting in 2230 fewer LTs. If transplant centers increase their risk tolerance for marginal grafts, utilization would decrease to 48%. The institution of “opt‐out” organ donation policies to increase the donor pool would still result in 1380 to 1866 fewer transplants. Ex vivo perfusion techniques that increase the use of marginal donor livers may stabilize LT volume. Otherwise, the number of LTs in the United States will decrease substantially over the next 15 years. In conclusion, the transplant community will need to accept inferior grafts and potentially worse posttransplant outcomes and/or develop new strategies for increasing organ donation and utilization in order to maintain the number of LTs at the current level. Liver Transpl 21:1040‐1050, 2015. © 2015 AASLD.
Intracardiac thrombosis during liver transplant: A 17‐year single‐institution study
Authors: Peiris Prith , Pai Sher‐Lu , Aniskevich Stephen , Crawford Claudia C. , Torp Klaus D. , Ladlie Beth L. , Shine Timothy S. , Taner C. Burcin , Nguyen Justin H.
Published: May 2015

Intracardiac thrombosis (ICT) during orthotopic liver transplantation (OLT) is an uncommon event. However, it is a devastating complication with high mortality when it occurs. This study aimed to identify possible predisposing factors for ICT during OLT. We retrospectively identified the cases of all patients with ICT during OLT at our institution from 1998 to 2014. Of 2750 OLTs performed, 10 patients had ICT intraoperatively. The patients' immediate prethrombosis intraoperative hemodynamic and coagulation values and thromboelastography (TEG) data were reviewed. Preexisting venous thrombosis, atrial fibrillation, and the prior placement of a transjugular intrahepatic portosystemic shunt for portal hypertension were noted in several patients and may be related to ICT during OLT. A high Model of End‐Stage Liver Disease score, low cardiac output, and sepsis did not appear to be associated with ICT. ICT occurred in some patients without the administration of antifibrinolytic agents. TEG and coagulation parameters did not appear to be helpful in predicting the onset of ICT. Four patients had ICT in both right‐ and left‐sided heart chambers; none of these 4 patients survived. All 6 patients with only right‐sided thrombus survived. In those who survived, improved hemodynamics and clot disappearance on transesophageal echocardiography (TEE) occurred over time, even without the use of thrombolytics. Whether this is because of endogenous thrombolysis or distal clot propagation into the pulmonary vasculature, or both, is unclear. Tissue plasminogen activator may have a role in the resuscitation procedure. In conclusion, without the routine use of TEE during OLT, the incidence of ICT will remain an under‐recognized event. Liver Transpl 21:1280‐1285, 2015. © 2015 AASLD.
Charge Carrier Transport and Photogeneration in P3HT:PCBM Photovoltaic Blends
Authors: Laquai Frédéric , Andrienko Denis , Mauer Ralf , Blom Paul W. M.
Published: May 2015

This article reviews the charge transport and photogeneration in bulk‐heterojunction solar cells made from blend films of regioregular poly(3‐hexylthiophene) (RR‐P3HT) and methano­fullerene (PCBM). The charge transport, specifically the hole mobility in the RR‐P3HT phase of the polymer:fullerene photovoltaic blend, is dramatically affected by thermal annealing. The hole mobility increases more than three orders of magnitude and reaches a value of up to 2 × 10−4 cm2 V−1 s−1 after the thermal annealing process as a result of an improved semi‐crystallinity of the film. This significant increase of the hole mobility balances the electron and hole mobilities in a photovoltaic blend in turn reducing space‐charge formation, and this is the most important factor for the strong enhancement of the photovoltaic efficiency compared to an as cast, that is, non‐annealed device. In fact, the balanced charge carrier mobility in RR‐P3HT:PCBM blends in combination with a field‐ and temperature‐independent charge carrier generation and greatly reduced non‐geminate recombination explains the large quantum efficiencies mea­sured in P3HT:PCBM photovoltaic devices.

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Chromatin remodelling and histone mRNA accumulation in bovine germinal vesicle oocytes
Authors: Labrecque R. , Lodde V. , Dieci C. , Tessaro I. , Luciano A. M. , Sirard M. A.
Published: May 2015

Major remodelling of the chromatin enclosed within the germinal vesicle occurs towards the end of oocyte growth in mammals, but the mechanisms involved in this process are not completely understood. In bovine, four distinct stages of chromatin compaction—ranging from a diffused state (GV0) to a fully compacted configuration (GV3)—are linked to the gradual acquisition of developmental potential. To better understand the molecular events and to identify mRNA modulations occurring in the oocyte during the GV0‐to‐GV3 transition, transcriptomic analysis was performed with the EmbryoGENE microarray platform. The mRNA abundance of several genes decreased as chromatin compaction increased, which correlates with progressive transcriptional silencing that is characteristic of the end of oocyte growth. On the other hand, the abundance of some transcripts increased during the same period, particularly several histone gene transcripts from the H2A, H2B, H3, H4, and linker H1 family. In silico analysis predicted RNA‐protein interactions between specific histone transcripts and the bovine stem‐loop binding protein 2 (SLBP2), which helps regulate the translation of histone mRNA during oogenesis. These results suggest that some histone‐encoding transcripts are actively stored, possibly to sustain the needs of the embryo before genome activation. This dataset offers a unique opportunity to survey which histone mRNAs are needed to complete chromatin compaction during oocyte maturation and which are stockpiled for the first three cell cycles following fertilization. Mol. Reprod. Dev. 82: 450–462, 2015. © 2015 Wiley Periodicals, Inc.
LDPE/EVA/graphene nanocomposites with enhanced mechanical and gas permeability properties
Authors: Tayebi Meysam , Ramazani S.A Ahmad , Hamed Mosavian M. T. , Tayyebi Ahmad
Published: May 2015

In the present work, graphene oxide (GO) and reduced graphene oxide (RGO) were incorporated at low‐density polyethylene (LDPE)/ethylene vinyl acetate (EVA) copolymer blend using solution casting method. Monolayer GO with 1‐nm thickness and good transparency was synthesized using the well‐known Hummers's method. Fourier transform infrared and X‐ray photoelectron spectroscopy data exhibited efficient reduction of GO with almost high C/O ratio of RGO. Scanning electron microscopy showed the well distribution of GO and RGO within LDPE/EVA polymer matrix. The integrating effects of GO and RGO on mechanical and gas permeability of prepared films were examined. Young's modulus of nanocomposites are improved 65% and 92% by adding 7 wt% of GO and RGO, respectively. The tensile measurements showed that maximum tensile strength emerged in 3 wt% of loading for RGO and 5 wt% for GO. The measured oxygen and carbon dioxide permeability represented noticeably the attenuation of gas permeability in composite films compared with pristine LDPE/EVA blend. Copyright © 2015 John Wiley & Sons, Ltd.
Preparation and morphology control of three‐dimensional interconnected microporous PDMS for oil sorption
Authors: Si Pengxiang , Wang Jikui , Zhao Cong , Xu Heng , Yang Kun , Wang Wenqi
Published: May 2015

This study described an approach to impart controlled morphology and improved pore interconnectivity to poly(dimethylsiloxane) (PDMS) sponges for oil sorption by partially fusing the sugar particles together prior to creation of a continuous PDMS matrix. PDMS sponges with high absorption capacity, low water pickup, and remarkable reusability were fabricated by the polymerization of the PDMS prepolymer and a curing agent in cyclohexane. The PDMS sponge showed oil absorbency in the range from 790% to 4000% for various oils solvents, with the maximum absorption capacity reaching up to 23 times of its weight. Compressive modulus of PDMS subjected to sugar fusion for 24 hr was significantly increased to 1900 Mpa. The sponge also exhibited excellent repellency to corrosive strong acid and alkali. Besides, oil can be quickly adsorbed in tens of seconds and maintained for several months. Furthermore, PDMS sponges showed little loss of their absorption capacities and owned weights after 20 absorbing/recovering cycles. Copyright © 2015 John Wiley & Sons, Ltd.
Synthesis and non‐isothermal crystallization kinetics of poly(ethylene terephthalate)‐co‐poly(propylene glycol) copolymers
Authors: Qiu Dianluan , Zhang Pei , Zhang Shiyu , Sun Jun , Wang Jian‐jun , Dai Lixing
Published: May 2015

Poly(ethylene terephthalate)‐co‐poly(propylene glycol) (PET‐co‐PPG) copolymers with PPG ratio ranging from 0 to 0.90 mol% were synthesized by the melt copolycondensation. The intrinsic viscosity, structure, non‐isothermal crystallization behavior, nucleation and spherulitic growth of the copolymers were investigated by Ubbelohde viscometer, Proton Nuclear Magnetic Resonance (1H‐NMR), differential scanning calorimetry, and polarized optical microscopy, respectively. The non‐isothermal crystallization process of the copolymers was analyzed by Avrami, Ozawa, Mo's, Kissinger, and Dobreva methods, respectively. The results showed that the crystallizability of PET was apparently enhanced with incorporating a small amount of PPG, which first rose and then reduced with increasing amount of PPG in the copolymers at a given cooling rate. The crystallization mechanism was a three‐dimensional growth with both instantaneous and sporadic nucleation. Particularly, PET‐co‐PPG containing 0.60 mol% PPG exhibited the highest crystallizability among all the copolymers. Copyright © 2015 John Wiley & Sons, Ltd.
Active Layer Thickness Prediction on the Western Antarctic Peninsula
Authors: Wilhelm Kelly R. , Bockheim James G. , Kung Samuel
Published: May 2015

The effects of climate change along the climatically sensitive Western Antarctic Peninsula (WAP) on active layer dynamics have just begun to be monitored. But extreme climates and difficult access make borehole installation here challenging. This study was designed to examine the ability of two commonly used, minimally intrusive techniques (the Stefan and Kudryavtsev equations) to predict active layer temperature dynamics and maximum active layer thickness (ALT) on Amsler Island, on the WAP. The ALT in soils and unconsolidated materials was predicted to be between 4.7 and 8.7 m, and between 11.9 and 18.6 m in bedrock, consistent with measurements made in a 14.6 m deep borehole. The thermal model HYDRUS accurately predicted temperature dynamics at several monitored borehole depths. The success of the HYDRUS method indicates that the model can be a useful tool in predicting active layer temperatures and approximating ALTs in regions that are too difficult to install monitoring boreholes. Copyright © 2015 John Wiley & Sons, Ltd.
Antisite defects in nonstoichiometric Lu3Al5O12:Ce ceramic scintillators
Authors: Hu Chen , Liu Shuping , Shi Yun , Kou Huamin , Li Jiang , Pan Yubai , Feng Xiqi , Liu Qian
Published: May 2015

Antisite defects (ADs) in nonstoichiometric Lu3Al5O12:Ce (LuAG:Ce) were studied systematically by a combination of first‐principles calculation based on density functional theory (DFT), X‐ray diffraction (XRD), and electron spin resonance (ESR) experiments. Calculations illustrated that LuAl,16a AD is dominant in LuAG when an Lu2O3 excess exists. Nonstoichiometric LuAG:Ce ceramic with different Lu2O3 excess were prepared to verify the calculation results. The retrieved XRD lattice constants of Lu2O3 excess LuAG:Ce ceramics fit well with DFT calculation results on LuAl,16a AD model, and the same distorted Ce sites in single crystals were also found in LuAG:Ce ceramics by ESR, which suggests the existence of LuAl,16a ADs and they are dominant in nonstoichiometric LuAG:Ce ceramics, and thus measurable concentrations of ADs were detected in ceramics. This revealed that the formation of ADs is related to both temperature and chemical stoichiometry.

LuAl,16a antisite defects and nearest normal Lu sites.
Polycrystalline bismuth films: Correlation between grain structure and electron transport
Authors: Fedotov A. S. , Poznyak S. K. , Tsybulskaya L. S. , Shepelevich V. G. , Svito I. A. , Saad A. , Mazanik A. V. , Fedotov A. K.
Published: May 2015

Grain structure and the temperature dependences of resistivity, magnetoresistance, Hall and Seebeck coefficients measured in the range from 4 to 300 K were investigated for polycrystalline bismuth films obtained by the melt spinning (MS) and electrochemical deposition (ECD) methods. Charge‐carrier concentration and mobilities were calculated assuming the carrier scattering on acoustic deformation potential as the dominant scattering mechanism, parabolicity of holes dispersion law, implying the Lax model for L‐band electrons and neglecting the influence of L‐band holes on conductivity. The experimental results and calculations have demonstrated that the electrical properties of the Bi films studied are strongly affected by the grain‐boundary density.
Therapeutic Effect of Supercritical CO2 Extracts of Curcuma Species with Cancer Drugs in Rhabdomyosarcoma Cell Lines
Authors: Ramachandran Cheppail , Quirin Karl‐W. , Escalon Enrique A. , Lollett Ivonne V. , Melnick Steven J.
Published: May 2015

Synergistic effect of supercritical CO2 extracts of Curcuma species with conventional chemotherapeutic drugs was investigated in human alveolar (SJRH30) and embryonal (RD) rhabdomyosarcoma cell lines. The Curcuma amada (mango ginger) (CA) extract showed the highest levels of cytotoxicity with inhibitory concentration IC50 values of 7.133 µg/ml and 7.501 µg/ml for SJRH30 and RD cell lines, respectively, as compared with Curcuma longa (turmeric) and Curcuma xanthorrhiza (Javanese turmeric) extracts. CA showed synergistic cytotoxic effects with vinblastine (VBL) and cyclophosphamide (CP) as indicated by the combination index values of <1 for VBL + CA, CP + CA, and VBL + CP + CA combinations in both embryonal and alveolar rhabdomyosarcomas. When lower doses of CA (0.1–0.2 µg/ml) were combined with cancer drugs like CP and VBL, caspase‐3 activity increased significantly compared with individual agents and correlated with the percentage of apoptotic cells. CA in combination with VBL and CP induced a higher percentage of apoptosis than single agents in both cell lines. CA also modulated the expression of genes associated with intrinsic pathway of apoptosis (Bcl‐2, Bax, Bak, and p53) and also inhibited the expression of genes associated with inflammation such as COX‐2 and NF‐κB. Xenograft studies with SJRH30 tumors in nude mice showed that CA treatment inhibited tumor growth rate with and without VBL and increased the survival rate significantly. These results suggest that CA can be evaluated further as an adjuvant with cancer drugs for the treatment of rhabdomyosarcoma patients. Copyright © 2015 John Wiley & Sons, Ltd.
Isotopic disproportionation during hydrogen isotopic analysis of nitrogen‐bearing organic compounds
Authors: Nair Sreejesh , Geilmann Heike , Coplen Tyler B. , Qi Haiping , Gehre Matthias , Schimmelmann Arndt , Brand Willi A.
Published: May 2015

Rationale

High‐precision hydrogen isotope ratio analysis of nitrogen‐bearing organic materials using high‐temperature conversion (HTC) techniques has proven troublesome in the past. Formation of reaction products other than molecular hydrogen (H2) has been suspected as a possible cause of incomplete H2 yield and hydrogen isotopic fractionation.

Methods

The classical HTC reactor setup and a modified version including elemental chromium, both operated at temperatures in excess of 1400 °C, have been compared using a selection of nitrogen‐bearing organic compounds, including caffeine. A focus of the experiments was to avoid or suppress hydrogen cyanide (HCN) formation and to reach quantitative H2 yields. The technique also was optimized to provide acceptable sample throughput.

Results

The classical HTC reaction of a number of selected compounds exhibited H2 yields from 60 to 90 %. Yields close to 100 % were measured for the experiments with the chromium‐enhanced reactor. The δ2H values also were substantially different between the two types of experiments. For the majority of the compounds studied, a highly significant relationship was observed between the amount of missing H2 and the number of nitrogen atoms in the molecules, suggesting the pyrolytic formation of HCN as a byproduct. A similar linear relationship was found between the amount of missing H2 and the observed hydrogen isotopic result, reflecting isotopic fractionation.

Conclusions

The classical HTC technique to produce H2 from organic materials using high temperatures in the presence of glassy carbon is not suitable for nitrogen‐bearing compounds. Adding chromium to the reaction zone improves the yield to 100 % in most cases. The initial formation of HCN is accompanied by a strong hydrogen isotope effect, with the observed hydrogen isotope results on H2 being substantially shifted to more negative δ2H values. The reaction can be understood as an initial disproportionation leading to H2 and HCN with the HCN‐hydrogen systematically enriched in 2H by more than 50 ‰. In the reaction of HCN with chromium, H2 and chromium‐containing solid residues are formed quantitatively. Copyright © 2015 John Wiley & Sons, Ltd.
Leakage‐resilient certificate‐based encryption
Authors: Yu Qihong , Li Jiguo , Zhang Yichen
Published: May 2015

Certificate‐based encryption is a new cryptography primitive, which can be used to construct efficient public key infrastructure. However, side‐channel attacks are not considered in certificate‐based encryption. In order to capture these attacks, we formalize security model of certificate‐based encryption with leakage resilience. Furthermore, we present a leakage‐resilient certificate‐based encryption (LR‐CBE) scheme. To the best of our knowledge, this is the first LR‐CBE scheme. Based on decision bilinear Diffie‐Hellman assumption and decision generalized bilinear Diffie‐Hellman assumption, we prove that our scheme is secure against adaptive chosen ciphertext attacks in the random oracle model. Our scheme includes a certificate‐based key encapsulation algorithm and a symmetric encryption algorithm, where the encapsulated information is a symmetric key that is used to encrypt message. In order to obtain leakage‐resilient property, two‐source extractor is used to randomize the symmetric key. The designed scheme can resist entropy leakage. The performance analysis of leakage resilience shows that the relative leakage ratio almost amounts to 1. Copyright © 2015 John Wiley & Sons, Ltd.
A new approach to express ToF SIMS depth profiling
Authors: Yunin Pavel Andreevich , Drozdov Yurii Nikolaevich , Drozdov Mikhail Nikolaevich
Published: May 2015

We propose a new approach to express SIMS depth profiling on a TOF.SIMS‐5 time‐of‐flight mass spectrometer. The approach is based on the instrument capability to independently perform raster scans of sputter and probe ion beams. The probed area can be much smaller than the diameter of a sputter ion beam, like in the AES depth profiling method. This circumstance alleviates limitations on the sputter beam–raster size relation, which are critical in other types of SIMS, and enables analysis on a curved‐bottomed sputter crater. By considerably reducing the raster size, it is possible to increase the depth profiling speed by an order of magnitude without radically degrading the depth resolution. A technique is proposed for successive improvement of depth resolution through profile recovery with account for the developing curvature of the sputtered crater bottom in the probed area. Experimental study of the crater bottom form resulted in implementing a method to include contribution of the instrumental artifacts in a nonstationary depth resolution function within the Hofmann's mixing–roughness–information depth model. The real‐structure experiment has shown that the analysis technique combining reduction of a raster size with a successive nonstationary recovery ensures high speed of profiling at ~100 µm/h while maintaining the depth resolution of about 30 nm at a 5 µm depth. Copyright © 2015 John Wiley & Sons, Ltd.
Dichlorocarbene‐Functionalized Fluorographene: Synthesis and Reaction Mechanism
Authors: Lazar Petr , Chua Chun Kiang , Holá Kateřina , Zbořil Radek , Otyepka Michal , Pumera Martin
Published: May 2015

Halogen functionalization of graphene is an important branch of graphene research as it provides opportunities to tailor the band gap and catalytic properties of graphene. Monovalent C–X bond obviates pitfalls of functionalization with atoms of groups 13, 15, and 16, which can introduce various poorly defined groups. Here, the preparation of functionalized graphene containing both fluorine and chlorine atoms is shown. The starting material, fluorographite, undergoes a reaction with dichlorocarbene to provide dichlorocarbene‐functionalized fluorographene (DCC‐FG). The material is characterized by X‐ray photoelectron spectroscopy, Raman spectroscopy, and high‐resolution transmission electron microscopy with X‐ray dispersive spectroscopy. It is found that the chlorine atoms in DCC‐FG are distributed homogeneously over the entire area of the fluorographene sheet. Further density functional theory calculations show that the mechanism of dichlorocarbene attack on fluorographene sheet is a two‐step process. Dichlorocarbene detaches fluorine atoms from fluorographene sheet and subsequently adds to the newly formed sp2 carbons. Halogenated graphene consisting of two (or eventually three) types of halogen atoms is envisioned to find its way as new graphene materials with tailored properties.
Progress of Microfluidics for Biology and Medicine
Authors: Chen Jingdong , Chen Di , Xie Yao , Yuan Tao , Chen Xiang
Published: May 2015

Microfluidics has been considered as a potential technology to miniaturize the conventional equipments and technologies. It offers advantages in terms of small volume, low cost, short reaction time and highthroughput. The applications in biology and medicine research and related areas are almost the most extensive and profound. With the appropriate scale that matches the scales of cells, microfluidics is well positioned to contribute significantly to cell biology. Cell culture, fusion and apoptosis were successfully performed in microfluidics. Microfluidics provides unique opportunities for rare circulating tumor cells isolation and detection from the blood of patients, which furthers the discovery of cancer stem cell biomarkers and expands the understanding of the biology of metastasis. Nucleic acid amplification in microfluidics has extended to single-molecule, high-throughput and integration treatment in one chip. DNA computer which is based on the computational model of DNA biochemical reaction will come into practice from concept in the future. In addition, microfluidics offers a versatile platform for protein-protein interactions, protein crystallization and high-throughput screening. Although microfluidics is still in its infancy, its great potential has already been demonstrated and will provide novel solutions to the high-throughput applications.
Measurement of the Radiographic Anatomy of the Small and Ring Metacarpals using Computerized Tomographic Scans
Authors: Rivlin Michael , Kim Nayoung , Lutsky Kevin F. , Beredjiklian Pedro K.
Published: May 2015

Background

To date, only plain radiographic definitions of normal anatomical parameters have been described. Our study aims to describe normal anatomic measurements of small and ring metacarpals using a novel digital reconstruction technique based on raw CT image data. We hypothesize that current plain radiographic data incorrectly describes normal metacarpal anatomy in the lateral plane.

Methods

Thirty-five scans of the small and 30 scans of the ring metacarpals form the basis for this study. Using a custom digital 3D image reformatting software, CT sections were reconstructed in the plane of each studied metacarpal. The 3D images were converted to sagittal and coronal weighted projections to represent lateral and posteroanterior (PA) 2D images that are equivalent to “perfect orthogonal” radiographs. Using a customized image measurement program, shaft lengths, shaft-bending angle (SBA), and capital-axis angle (CAA) were measured.

Results

Our results show that CAA averaged 14 and 12° in the ring and small metacarpals, respectively. Apex dorsal SBA averaged 12 and 10° in the ring and small metacarpals, respectively. On the PA images, the shafts are nearly straight. In contrast to prior reported values, we found the CAA to be less acute and the metacarpal curvature less pronounced on the lateral projection. We also demonstrated that much of the metacarpal apex dorsal bend is in the shaft itself.

Conclusion

Normal anatomic parameters of metacarpals are based primarily on radiographic data, and as such are limited due to bony overlap in the lateral plane, as well as imperfect radiographic projections that are known to distort anatomical relationships. This novel method of image reconstruction eliminates metacarpal overlap and defines precise anatomical reference for metacarpals.
On the friction and adhesion hysteresis between polymer brushes attached to curved surfaces: Rate and solvation effects
Authors: de Beer Sissi , Kenmoé G. Djuidjé , Müser Martin H.
Published: May 2015

Computer simulations of friction between polymer brushes are usually simplified compared to real systems in terms of solvents and geometry. In most simulations, the solvent is only implicit with infinite compressibility and zero inertia. In addition, the model geometries are parallel walls rather than curved or rough as in reality. In this work, we study the effects of these approximations and more generally the relevance of solvation on dissipation in polymer-brush systems by comparing simulations based on different solvation schemes. We find that the rate dependence of the energy loss during the collision of brush-bearing asperities can be different for explicit and implicit solvent. Moreover, the non-Newtonian rate dependences differ noticeably between normal and transverse motion, i.e., between head-on and off-center asperity collisions. Lastly, when the two opposing brushes are made immiscible, the friction is dramatically reduced compared to an undersaturated miscible polymer-brush system, irrespective of the sliding direction.
Further Evidence ofDepdc7Dna Hypomethylation in Depression: a Study in Adult Twins
Authors: Córdova-Palomera A. , Fatjó-Vilas M. , Palma-Gudiel H. , Blasco-Fontecilla H. , Kebir O. , Fañanás L.
Published: May 2015

Late and early stressful factors have widely been recognized to play a role in the aetiology of depression. Recent research indicates that such adverse environmental stimuli may alter gene expression in humans via epigenetic modifications. While epigenetic changes such as DNA methylation are likely involved in these processes, it is still unknown what specific genomic loci may be hyper- or hypo-methylated in depression. The association between depressive symptoms during the last 30 days (Brief Symptom Inventory [BSI]) and peripheral-blood DNA methylation levels at genomic loci previously reported as epigenetically altered in saliva and brain of depressive patients was evaluated in a community sample of 34 adult Caucasian MZ twins (17 pairs). Intrapair DNA methylation differences in an intron ofDEPDC7(chr11:33040743) were associated with intrapair differences in current depressive symptoms. Accordingly, a site-specific 10% DNA hypomethylation in a co-twin would correlate with a current depressive symptom score around 3.1 BSI points above the score of his/her less-depressed co-twin. These findings indicate thatDEPDC7hypomethylation in peripheral blood DNA may be associated with recent depressive symptomatology, in line with previous results.
Biogeochemical specifics of sapropel formation in Cisbaikalian undrained lakes (exemplified by Lake Ochki)
Authors: Leonova G.A. , Bobrov V.A. , Krivonogov S.K. , Bogush A.A. , Bychinskii V.A. , Mal’tsev A.E. , Anoshin G.N.
Published: May 2015

The biogeochemistry of organic lacustrine sediments (sapropels) has been poorly studied in Siberia. In this paper we show the specifics of sapropel formation caused by low pH and mineralization of water by the example of Lake Ochki in Cisbaikalia. The main sources of organic matter are zoo- and phytoplankton, which concentrate mostly basic chemical elements and also some alkaline, alkali-earth, and chalcophile elements and move them to the sediment. The calculated enrichment factors (EF) have shown that the lake plankton is strongly enriched with phosphorus and chalcophile elements. The calculations have also revealed a great contribution of the plankton to the elemental composition of sapropel (Mebio, %): P (≈100), Cd (57), Br (45), Hg (40), Se and Na (30), Zn (23), K (21), and Ca (15). Elements are rather uniformly distributed throughout the 3.2 m thick sapropel layer. Lithophile elements (Al, Sc, Ti, Y, Zr, Nb) and LREE are mostly from a terrigenous source. The high contents of mobile elements (Cd, Sb, Sn, Pb, Zn) in the upper part of sapropel are probably due to anthropogenic factors. The high Cu and Zn contents in some sapropel layers are probably related to the inflow of deep-level groundwaters, and the elevated contents of Hg, Cd, and Sb might have been caused by forest fires.
Nonlinear waves and solitons in models of fault block geological media
Authors: Bykov V.G.
Published: May 2015

This is an overview of theoretical research on solitons and other nonlinear waves induced by deformation in fault block (fragmented) geological media, including a brief description of available models with their geophysical and geodynamic applications. The cited models correspond to the classical and perturbed sine-Gordon equations and use the rotation angle and displacement of fault blocks as dynamic variables. The models simulate kinematics and dynamics of traveling deformation fronts (kinks and solitons) generated in faulted rocks. The sine-Gordon equation is presented in its seismological and geomechanic applications for description of earthquake data and modeling of strain waves, faulting patterns, and subduction processes, including slow earthquakes and periodic episodic tremor and slow slip (ETS) effects.
Discriminación y violencia contra los estudiantes de medicina de la Universidad de Caldas
Authors: Moreno-Cubillos Carmen Leonor , Sepúlveda-Gallego Luz Elena
Published: May 2015

Objetivo: Evidenciar y caracterizar los actos de discriminación y violencia, que suceden entre los estudiantes del programa de medicina de la Universidad de Caldas (Colombia).  Materiales y método: Estudio descriptivo y de corte, realizado entre el segundo periodo académico de 2010 y el primero de 2011, con fuente de información primaria y muestra seleccionada aleatoriamente constituida por 88 estudiantes de pregrado.

Resultados: El 86.4% de los estudiantes tienen antecedente de haber sido víctima de alguno de los siguientes eventos estudiados: discriminación por aspecto físico, procedencia, género, estrato socioeconómico, orientación sexual y religión; agresión verbal, física y psicológica; abuso de autoridad; acoso laboral; amenaza o intimidación; sanción o castigo; chantaje; burlas, piropos o gestos obscenos; exclusión y acoso sexual. Los tipos de violencia más frecuentemente reportados fueron abuso de autoridad y agresión psicológica.

Conclusión: Los resultados muestran la existencia de discriminación y violencia contra los estudiantes de medicina, y fundamentan la necesidad de realizar intervenciones desde el punto de vista administrativo y de bienestar universitario.
Confiabilidad en la medición
Authors: Reidl-Martínez Lucy María
Published: May 2015

En la investigación educativa de tipo cuantitativo, los instrumentos para la recopilación de información deben llevar a la validez y confiabilidad de los resultados. Una pregunta que los investigadores se hacen con frecuencia es la referida, a qué tan alto o de qué tamaño tiene que ser el coeficiente de confiabilidad. Esto dependerá del propósito e importancia de las decisiones que se tomarán con base en los puntajes obtenidos por los sujetos. La confiabilidad es un atributo necesario en todas las pruebas cuantitativas que se utilicen para evaluar a alguien. El presente escrito tiene como propósito abordar la confiabilidad de la medición. Para lograrlo se revisan los siguientes puntos: teoría de la medición del error, modelo dominio-muestra, estabilidad temporal o coeficiente de estabilidad, formas paralelas o coeficiente de estabilidad y equivalencia y los coeficientes de consistencia interna más usuales.
Factores relacionados con el rendimiento académico en alumnos de fisiopatología
Authors: Sanguinetti José María , López Raquel , Vieta María Eugenia , Berruezo Silvana , Chagra Carolina
Published: May 2015

Introducción: El rendimiento académico está relacionado con diferentes variables.

Objetivos: Evaluar factores sociales, demográficos y hábitos, así como determinar su relación con el rendimiento académico.

Material y métodos: Trabajo observacional, transversal, correlacional entre abril y noviembre de 2012. Se realizó una encuesta a alumnos de Fisiopatología, de la Universidad Nacional de Salta y se constató en noviembre quienes habían regularizado la asignatura. Variables estudiadas: edad, sexo, provincia de origen, condición laboral, si tiene computadora, frecuencia de uso de correo electrónico, utilización de redes sociales, práctica regular de deportes, actividad en organización no gubernamental (ONG), nivel de satisfacción con la carrera, libros leídos en el último año, aprobación de Anatomía, si cursaba por primera vez, situación económica, tipo de educación secundaria.

Materiales y método: Medidas de resumen y comparativo con Test de Fisher para tablas de contingencia, estudiando la relación de: provincia de origen, actividad laboral, actividad en organizaciones no gubernamentales (ONG), hábitos de lectura, si cursaba por primera vez y final de Anatomía aprobado.

Resultados: Edad promedio 21.5 años, 91% sexo femenino, procedentes de Salta 70%, el 23.9% trabajan, 80.3% tienen PC, el 63.8% acceso a internet y el 86.1% Facebook®. El 14% checa diariamente su correo electrónico. El 36.7% practica deportes regularmente y el 25.5% participa en ONG. El 50.5% está “muy satisfecho” con su carrera, sólo el 43.4% leyó dos o más libros en el último año. El 50.3% aprobó Anatomía, el 55.3% cursaba por primera vez y el 52.1% percibía su situación económica como mala o regular. El 63.82% provenía de escuelas públicas y el 41.48% regularizó la materia. Análisis comparativo: Haber aprobado Anatomía y leer dos o más libros se relacionaron con un mejor rendimiento académico; el resto de las variables estudiadas no mostraron relación.

Conclusiones: Es importante tener en cuenta el perfil del estudiante, sus intereses y hábitos para el desarrollo de estrategias, que mejoren el rendimiento académico.
Personalidad, aprendizaje y rendimiento académico en medicina
Authors: Torres-Acosta Noel David , Rodríguez-Gómez Jaime , Acosta-Vargas Miriam
Published: May 2015

Introducción: El éxito académico durante la vida estudiantil se ve afectado por muchos factores. La personalidad, de acuerdo las Five Factor Model y los enfoques de aprendizaje (profundo, estratégico y superficial) han mostrado ser condicionantes importantes del rendimiento académico.

Objetivo: Encontrar las correlaciones entre enfoques de aprendizaje-promedio de calificaciones (PC), factores de personalidad-PC, enfoques de aprendizaje-factores de personalidad.Material y métodos: Estudio observacional, analítico, transversal y prospectivo. Población de estudio: 204 estudiantes de medicina en una universidad de Nuevo León. Se utilizaron Big Five Inventory (BFI) para medir la personalidad y Approaches and Study Skills Inventory for Students (ASSIST) para medir los enfoques de aprendizaje. Se utilizó correlación r de Pearson para ver las relaciones entre las variables principales del estudio y análisis discriminante para encontrar las variables que mejor describen el desempeño académico.

Resultados: Los resultados mostraron correlaciones significativas entre PC y enfoque profundo, PC y enfoque superficial y PC-responsabilidad de manera general. Asimismo, hubo correlaciones significativas entre neuroticismo-enfoque superficial y enfoque profundo, y los factores de responsabilidad y apertura a la experiencia. En el análisis discriminante se vio que el enfoque profundo y el factor de responsabilidad son los que mejor diferenciaron a los subgrupos.

Discusión: El presente estudio demuestra una asociación significativa entre el factor de responsabilidad y el enfoque profundo con el rendimiento académico, lo que concuerda con estudios previos.

Conclusión: Se sugiere realizar estudios similares utilizando BFI y ASSIST para acoplarlos más a la realidad mexicana.
Distractores en preguntas de opción múltiple para estudiantes de medicina: ¿cuál es su comportamiento en un examen sumativo de altas consecuencias?
Authors: Jurado-Núñez Alma , Flores-Hernández Fernando , Delgado-Maldonado Laura , Sommer-Cervantes Hermann , Martínez-González Adrián , Sánchez- Mendiola Melchor
Published: May 2015

Introducción: Los exámenes de opción múltiple son la herramienta más utilizada en la evaluación del conocimiento en estudiantes de medicina. Se ha demostrado que tres opciones para cada ítem son suficientes, sin embargo, muchos exámenes en nuestro medio aún están compuestos por preguntas con cinco opciones. El estudio de los distractores no funcionales (DNF) es necesario para mejorar la calidad de los exámenes. Objetivo: Identificar los DNF y su comportamiento en una evaluación sumativa de altas consecuencias en estudiantes de medicina. Método: Se realizó análisis psicométrico del Examen Profesional Teórico de la Facultad de Medicina de la Universidad Nacional Autónoma de México (UNAM), en la versión de 2008. Se calcularon dificultad, discriminación y correlación punto-biserial de cada ítem y de sus cuatro distractores. Se obtuvo la frecuencia de preguntas con cero a cuatro DNF y se valoraron las diferencias de DNF por ítem y sus características psicométricas. Se contrastó el comportamiento psicométrico del examen completo, con una versión en la que se eliminaron los ítems con cuatro DNF. Resultados: El examen tuvo 420 reactivos de opción múltiple con cinco opciones de respuesta, fue contestado por 882 sustentantes. El instrumento tuvo un alfa de Cronbach de 0.93. De los 1 680 distractores evaluados, sólo 788 (46.9%) fueron funcionales. Más de dos tercios del total de ítems contaron con dos o más DNF. Se encontró un promedio de 2.12 ± 0.99 DNF por ítem, la mayoría de los cuales fueron elegidos por menos de 5% de los sustentantes. A mayor cantidad de DNF, mayor índice de dificultad y menor poder de discriminación de los ítems. Conclusiones: Los ítems con dos distractores funcionales comprenden la mayoría de los reactivos del examen. Dos distractores plausibles representan una alternativa asequible para elaborar los ítems, manteniendo o mejorando la confiabilidad y el perfil psicométrico de este tipo de evaluaciones.
Un acercamiento a los métodos mixtos de investigación en educación médica
Authors: Hamui-Sutton Alicia
Published: May 2015

Los métodos mixtos (MM) combinan la perspectiva cuantitativa (cuanti) y cualitativa (cuali) en un mismo estudio, con el objetivo de darle profundidad al análisis cuando las preguntas de investigación son complejas. Más que la suma de resultados cuanti y cuali, la metodología mixta es una orientación con su cosmovisión, su vocabulario y sus propias técnicas, enraizada en la filosofía pragmática con énfasis en las consecuencias de la acción en las prácticas del mundo real. En este artículo se presentan los cuatro modelos de MM más utilizados en estudios relacionados con las ciencias de la salud en las últimas dos décadas, estos son: 1) modelo para desarrollar instrumentos; 2) modelo explicativo o aclaratorio; 3) modelo de triangulación; y 4) modelo de transformación longitudinal, así como algunos lineamientos para su utilización en la investigación educativa. Los MM permiten ampliar las preguntas y las teorías para dar cuenta de la realidad e incidir en los procesos de enseñanza y aprendizaje. Las respuestas obtenidas a través de la aplicación de MM son ricas, significativas y aportan a la comprensión de los fenómenos educativos que a su vez hacen surgir nuevas preguntas. Los MM le ofrecen al investigador la oportunidad de descubrir orientaciones novedosas, ensayar con variadas estrategias y encontrar sentidos que van más allá de aquellos derivados del uso de un solo método.
Who Struggles Most in Making a Career Choice and Why? Findings From a Cross-Sectional Survey of Australian High-School Students
Authors: Galliott Natal’ya , Graham Linda J. , Sweller Naomi
Published: May 2015

This article reports findings from an empirical study examining the influence of student background and educational experiences on the development of career choice capability. Secondary school students attending Years 9–12 (N= 706) in New South Wales, Australia, were invited to participate in an online survey that sought to examine factors influencing their readiness to make a career choice. The survey included questions relating to student demographics, parental occupation, attitudes to school and to learning, career aspirations, and students’ knowledge of the further education or skills required to achieve their desired goal. We found no significant differences in the proportions of students who were ‘uncertain’ of their future career aspirations with respect to their individual characteristics, such as age and gender. There were, however, significant differences in relation to students’ family background, and their perceptions associated with their own academic abilities and self-efficacy.
Empirical and theoretical study of atelostomate (Echinoidea, Echinodermata) plate architecture: using graph analysis to reveal structural constraints
Authors: Saucède Thomas , Laffont Rémi , Labruère Catherine , Jebrane Ahmed , François Eric , Eble Gunther J. , David Bruno
Published: May 2015

Describing patterns of connectivity among organs is essential for identifying anatomical homologies among taxa. It is also critical for revealing morphogenetic processes and the associated constraints that control the morphological diversification of clades. This is particularly relevant for studies of organisms with skeletons made of discrete elements such as arthropods, vertebrates, and echinoderms. Nonetheless, relatively few studies devoted to morphological disparity have considered connectivity patterns as a level of morphological organization or developed comparative frameworks with proper tools. Here, we analyze connectivity patterns among apical plates in Atelostomata, the most diversified clade among irregular echinoids. The clade comprises approximately 1600 fossil and Recent species (e.g., 25% of post-Paleozoic species of echinoids) and shows high levels of morphological disparity. Plate connectivity patterns were analyzed using tools and statistics of graph theory. To describe and explore the diversity of connectivity patterns among plates, we symbolized each pattern as a graph in which plates are coded as nodes that are connected pairwise by edges. We then generated a comparative framework as a morphospace of connections, in which the disparity of plate patterns observed in nature was mapped and analyzed. Main results show that apical plate patterns are both highly disparate between and within atelostomate groups and limited in number; overall, they also constitute small, compact, and simple structures compared to possible random patterns. Main traits of the evolution of apical plate patterns reveal the existence of strong morphogenetic constraints that are phylogenetically determined. In contrast, evolutionary radiations within atelostomates were accompanied by a clear increase in disparity, suggesting a release of some constraints at the origin of clades.
Nothing in (sponge) biology makes sense – except when based on holotypes
Authors: Erpenbeck Dirk , Ekins Merrick , Enghuber Nicole , Hooper John N.A. , Lehnert Helmut , Poliseno Angelo , Schuster Astrid , Setiawan Edwin , De Voogd Nicole J. , Wörheide Gert , Van Soest Rob W.M.
Published: May 2015

Sponge species are infamously difficult to identify for non-experts due to their high morphological plasticity and the paucity of informative morphological characters. The use of molecular techniques certainly helps with species identification, but unfortunately it requires prior reference sequences. Holotypes constitute the best reference material for species identification, however their usage in molecular systematics and taxonomy is scarce and frequently not even attempted, mostly due to their antiquity and preservation history. Here we provide case studies in which we demonstrate the importance of using holotype material to answer phylogenetic and taxonomic questions. We also demonstrate the possibility of sequencing DNA fragments out of century-old holotypes. Furthermore we propose the deposition of DNA sequences in conjunction with new species descriptions.