bluuebunny/crossref_metadata_2025_split huggingface dataset:
Caffeine and risk of Parkinson's disease in a large cohort of men and women
Authors: Palacios Natalia , Gao Xiang , McCullough Marjorie L. , Schwarzschild Michael A. , Shah Roma , Gapstur Susan , Ascherio Alberto 
Published: August 2012

AbstractCaffeine consumption has been associated with a reduced risk of Parkinson's disease (PD). The association is strong and consistent in men, but uncertain in women, possibly because of an interaction with hormone replacement therapy (HRT). We sought to confirm these findings using data on PD incidence in the Cancer Prevention Study II Nutrition Cohort (CPS II–Nutrition), a large, prospective study of men and women. We conducted a prospective study of caffeine intake and risk of PD within the CPS II Nutrition Cohort. Intakes of coffee and other sources of caffeine were assessed at baseline. Incident cases of PD (n = 317; 197 men and 120 women) were confirmed by treating physicians and medical record review. Relative risks (RRs) were estimated using proportional hazards models, adjusting for age, smoking, and alcohol consumption. After adjustment for age, smoking, and alcohol intake, high caffeine consumption was associated with a reduced risk of PD. The RR comparing the 5th to the 1st quintile of caffeine intake was 0.43 (95% confidence interval [CI]: 0.26, 0.71; P trend = <0.002) in men, and 0.61 (95% CI: 0.34, 1.09; P trend = 0.05) in women. Among women, this association was stronger among never users of HRT (RR = 0.32) than among ever users (RR = 0.81; P interaction = 0.15). Consumption of decaffeinated coffee was not associated with PD risk. Findings from this large, prospective study of men and women are consistent with a protective effect of caffeine intake on PD incidence, with an attenuating influence of HRT in women. © 2012 Movement Disorder Society
Short latency activation of cortex by clinically effective thalamic brain stimulation for tremor
Authors: Walker Harrison C. , Huang He , Gonzalez Christopher L. , Bryant James E. , Killen Jeffrey , Knowlton Robert C. , Montgomery Erwin B. , Cutter Gary C. , Yildirim Abidin , Guthrie Bart L. , Watts Ray L. 
Published: August 2012

AbstractDeep brain stimulation (DBS) relieves disabling symptoms of neurologic and psychiatric diseases when medical treatments fail, yet its therapeutic mechanism is unknown. We hypothesized that ventral intermediate (VIM) nucleus stimulation for essential tremor activates the cortex at short latencies, and that this potential is related to the suppression of tremor in the contralateral arm. We measured cortical activity with electroencephalography in 5 subjects (seven brain hemispheres) across a range of stimulator settings, and reversal of the anode and cathode electrode contacts minimized the stimulus artifact, allowing visualization of brain activity. Regression quantified the relationship between stimulation parameters and both the peak of the short latency potential and tremor suppression. Stimulation generated a polyphasic event‐related potential in the ipsilateral sensorimotor cortex, with peaks at discrete latencies beginning less than 1 ms after stimulus onset (mean latencies 0.9 ± 0.2, 5.6 ± 0.7, and 13.9 ± 1.4 ms, denoted R1, R2, and R3, respectively). R1 showed more fixed timing than the subsequent peaks in the response (P < 0.0001, Levene's test), and R1 amplitude and frequency were both closely associated with tremor suppression (P < 0.0001, respectively). These findings demonstrate that effective VIM thalamic stimulation for essential tremor activates the cerebral cortex at approximately 1 ms after the stimulus pulse. The association between this short latency potential and tremor suppression suggests that DBS may improve tremor by synchronizing the precise timing of discharges in nearby axons and, by extension, the distributed motor network to the stimulation frequency or one of its subharmonics. © 2012 Movement Disorder Society
Kalman filter techniques for accelerated Cartesian dynamic cardiac imaging
Authors: Feng Xue , Salerno Michael , Kramer Christopher M. , Meyer Craig H. 
Published: August 2012

AbstractIn dynamic MRI, spatial and temporal parallel imaging can be exploited to reduce scan time. Real‐time reconstruction enables immediate visualization during the scan. Commonly used view‐sharing techniques suffer from limited temporal resolution, and many of the more advanced reconstruction methods are either retrospective, time‐consuming, or both. A Kalman filter model capable of real‐time reconstruction can be used to increase the spatial and temporal resolution in dynamic MRI reconstruction. The original study describing the use of the Kalman filter in dynamic MRI was limited to non‐Cartesian trajectories because of a limitation intrinsic to the dynamic model used in that study. Here the limitation is overcome, and the model is applied to the more commonly used Cartesian trajectory with fast reconstruction. Furthermore, a combination of the Kalman filter model with Cartesian parallel imaging is presented to further increase the spatial and temporal resolution and signal‐to‐noise ratio. Simulations and experiments were conducted to demonstrate that the Kalman filter model can increase the temporal resolution of the image series compared with view‐sharing techniques and decrease the spatial aliasing compared with TGRAPPA. The method requires relatively little computation, and thus is suitable for real‐time reconstruction. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
A robust genomic signature for the detection of colorectal cancer patients with microsatellite instability phenotype and high mutation frequency
Authors: Tian Sun , Roepman Paul , Popovici Vlad , Michaut Magali , Majewski Ian , Salazar Ramon , Santos Cristina , Rosenberg Robert , Nitsche Ulrich , Mesker Wilma E , Bruin Sjoerd , Tejpar Sabine , Delorenzi Mauro , Bernards Rene , Simon Iris 
Published: August 2012

AbstractMicrosatellite instability (MSI) occurs in 10–20% of colorectal tumours and is associated with good prognosis. Here we describe the development and validation of a genomic signature that identifies colorectal cancer patients with MSI caused by DNA mismatch repair deficiency with high accuracy. Microsatellite status for 276 stage II and III colorectal tumours has been determined. Full‐genome expression data was used to identify genes that correlate with MSI status. A subset of these samples (n = 73) had sequencing data for 615 genes available. An MSI gene signature of 64 genes was developed and validated in two independent validation sets: the first consisting of frozen samples from 132 stage II patients; and the second consisting of FFPE samples from the PETACC‐3 trial (n = 625). The 64‐gene MSI signature identified MSI patients in the first validation set with a sensitivity of 90.3% and an overall accuracy of 84.8%, with an AUC of 0.942 (95% CI, 0.888–0.975). In the second validation, the signature also showed excellent performance, with a sensitivity 94.3% and an overall accuracy of 90.6%, with an AUC of 0.965 (95% CI, 0.943–0.988). Besides correct identification of MSI patients, the gene signature identified a group of MSI‐like patients that were MSS by standard assessment but MSI by signature assessment. The MSI‐signature could be linked to a deficient MMR phenotype, as both MSI and MSI‐like patients showed a high mutation frequency (8.2% and 6.4% of 615 genes assayed, respectively) as compared to patients classified as MSS (1.6% mutation frequency). The MSI signature showed prognostic power in stage II patients (n = 215) with a hazard ratio of 0.252 (p = 0.0145). Patients with an MSI‐like phenotype had also an improved survival when compared to MSS patients. The MSI signature was translated to a diagnostic microarray and technically and clinically validated in FFPE and frozen samples. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Protocadherin 17 acts as a tumour suppressor inducing tumour cell apoptosis and autophagy, and is frequently methylated in gastric and colorectal cancers
Authors: Hu Xiaotong , Sui Xinbing , Li Lili , Huang Xuefeng , Rong Rong , Su Xianwei , Shi Qinglan , Mo Lijuan , Shu Xingsheng , Kuang Yeye , Tao Qian , He Chao 
Published: August 2012

AbstractGastric and colorectal cancers are among the most common cancers worldwide and cause serious cancer mortality. Both epigenetic and genetic disruptions of tumour suppressor genes (TSGs) are frequently involved in their pathogenesis. Here, we studied the epigenetic and genetic alterations of a novel TSG–PCDH17 and its functions in the pathogenesis of these tumours. We found that PCDH17 was frequently silenced and methylated in almost all gastric and colorectal tumour cell lines as well as in ∼95% of primary tumours, but not in normal gastric and colonic mucosa. Moreover, its deletion was detected in only 18% of gastric and 12% of colorectal cancer tissues, suggesting that epigenetic and genetic inactivation of PCDH17 are both involved in gastric and colorectal tumourigenesis. PCDH17 protein expression was significantly correlated with low tumour stage and less lymph node metastasis of gastric and colorectal cancer patients, indicating its potential as a tumour marker. Restoring PCDH17 expression inhibited tumour cell growth in vitro and in vivo through promoting apoptosis, as evidenced by increased TUNEL staining and caspase‐3 activation. Furthermore, PCDH17‐induced autophagy, along with increased numbers of autophagic vacuoles and up‐regulated autophagic proteins Atg‐5, Atg‐12 and LC3B II. Thus, PCDH17 acts as a tumour suppressor, exerting its anti‐proliferative activity through inducing apoptosis and autophagy, and is frequently silenced in gastric and colorectal cancers. PCDH17 methylation is a tumour‐specific event that could serve as an epigenetic biomarker for these tumours.
Developmental stage‐specific contribution of LGR5+ cells to basal and luminal epithelial lineages in the postnatal mammary gland
Authors: de Visser Karin E , Ciampricotti Metamia , Michalak Ewa M , Tan David Wei‐Min , Speksnijder Ewoud N , Hau Cheei‐Sing , Clevers Hans , Barker Nick , Jonkers Jos 
Published: August 2012

AbstractThe leucine‐rich repeat‐containing heterotrimeric guanine nucleotide‐binding protein‐coupled receptor 5 (LGR5) has been identified as a marker of cycling stem cells in several epithelial tissues, including small intestine, colon, stomach and hair follicle. To investigate whether LGR5 also marks mammary epithelial stem cells, we performed in situ lineage‐tracing studies and mammary gland reconstitutions with LGR5‐expressing mammary epithelial cells. Interestingly, the LGR5 progeny population in mammary epithelium switches from the luminal to the myoepithelial compartment during the first 12 days of postnatal development, likely reflecting local changes in Wnt signalling. Together, our findings point to a stage‐specific contribution of LGR5‐expressing cells to luminal and basal epithelial lineages during postnatal mammary gland development. Copyright © 2012 Pathological Society of Great Britain and Ireland.
Stem cell research points the way to the cell of origin for intracranial germ cell tumours
Authors: Tan Chris , Scotting Paul J 
Published: August 2012

AbstractGerm cell tumours found in the brain (intracranial GCTs) are a very unusual class of tumour for two reasons. First, they include a very diverse range of histological subtypes classified together due to their proposed common cell of origin. Second, this proposed cell of origin, the germ cell progenitor, would not normally be found in the tissue where these tumours arise. This is in contrast to all other primary brain tumours, in which the cell of origin is believed to be a brain cell. Indeed, no other class of primary cancer arises from a cell from a distant organ. This theory for the origins of intracranial GCTs has been in place for many decades, but recent data arising from studies of induced pluripotency for regenerative medicine raise serious questions about this dogma. Here we review the cellular origins of intracranial GCTs in the light of these new data and reanalyse the existing data on the biology of this unusual class of tumours. Together, these considerations lead us to conclude that the evidence now falls in favour of a model in which these tumours arise from the transformation of endogenous brain cells. This theory should inform future studies of the aetiology of these tumours and so lead the way to animal models in which to study their development and potential biological therapeutics. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Electro‐optical study of a ×1024 concentrator photovoltaic system
Authors: Pereira Alexandre , Dargent Loïc , Lorin Géraldine , Schwartz Wilfrid , Baffie Thierry , Mangeant Christophe , Mariotto Mathieu , de Salins Jean‐Edouard , Vives Guillaume 
Published: August 2012

ABSTRACTConcentrator photovoltaic (CPV) systems are one of the most promising technologies for future energy supply. Several studies reported the interest of using a Fresnel lens coupled with a secondary optical element in such a system. For high concentration factor, the optimization of the optical configuration plays a key role regarding electrical performances. On the other hand, the thermal management of the solar cell is also critical to ensure a better module efficiency. This paper presents a study of a ×1024 CPV system performances and a methodology for estimating the optical chain efficiency, the cell temperature impact and the alignment requirements. Module efficiencies were then measured as a function of the cell temperature and correlated to optical performances through current‐tension characterizations under real solar illumination conditions and the estimation of the power density received by the solar cell. The system yield was up to 27% for a cell temperature around 30 °C, confirming that high concentration ratio should be of great interest in the near future. A 1D model was also developed in order to quantify the possible improvements of this CPV system. Using a solar cell with an efficiency of 36.7% at ×600, we then demonstrated that the ×1024 CPV system could reach up to 30% in standard test conditions. Copyright © 2012 John Wiley & Sons, Ltd.
Gene expression analysis in prostate cancer: The importance of the endogenous control
Authors: Vajda Alice , Marignol Laure , Barrett Ciara , Madden Stephen F. , Lynch Thomas H. , Hollywood Donal , Perry Antoinette S. 
Published: August 2012

AbstractBACKGROUNDAberrant gene expression is a hallmark of cancer. Quantitative reverse‐transcription PCR (qRT‐PCR) is the gold‐standard for quantifying gene expression, and commonly employs a house‐keeping gene (HKG) as an endogenous control to normalize results; the choice of which is critical for accurate data interpretation. Many factors, including sample type, pathological state, and oxygen levels influence gene expression including putative HKGs. The aim of this study was to determine the suitability of commonly used HKGs for qRT‐PCR in prostate cancer.METHODSProstate cancer (LNCaP, 22Rv1, PC3, and DU145) and normal (PWR1E and RWPE1) cell lines were cultured in air and hypoxia. The performance of 16 HKGs was assessed using Normfinder and coefficient of variation. In silico promoter analysis was performed to identify putative hypoxia response elements (HREs). The impact of the endogenous control on expression levels of HIF1A and GSTP1 was investigated by qRT‐PCR in cell lines and tissue specimens respectively.RESULTSHypoxia altered expression of several HKGs: IPO8, B2M, and PGK1. The most stably expressed HKGs were ACTB, PPIA, and UBC. Both UBC and ACTB showed constitutive expression of HIF1A in air and hypoxia, while PGK1 falsely implied a sixfold hypoxia‐induced down‐regulation. In prostate tumors, UBC and PGK1 both revealed down‐regulation of GSTP1 relative to matched benign, whereas ACTB showed variability.CONCLUSIONSThis study demonstrates that no universal endogenous control exists for gene expression studies, even within one disease type. It highlights the importance of validating expression of intended HKGs between different sample types and environmental exposures. Prostate 73: 382–390, 2013. © 2012 Wiley Periodicals, Inc.
Deep level studies in high‐temperature annealed silicon wafers for layer transfer in thin‐film solar cells
Authors: Simoen Eddy , Depauw Valerie , Gordon Ivan , Poortmans Jef 
Published: August 2012

AbstractDeep‐level transient spectroscopy (DLTS) has been applied to high‐temperature annealed n‐ and p‐type Si wafers. The aim is to identify the deep levels responsible for the observed minority carrier lifetime degradation after thin‐film transfer to a glass substrate. Anneals have been performed at 1150 °C in H2 or Ar. Care has been taken to avoid radiation defect formation during the fabrication of the Al Schottky barriers used for DLTS. It is shown that besides a change in the carrier doping density and profile, an annealing‐induced electron trap at 0.43 eV below the conduction band edge can be found, which is related to a vacancy–impurity complex.
UV‐illuminated dielectrophoresis by two‐dimensional electron gas (2DEG) in AlGaN/GaN heterojunction
Authors: Fu Junxue , Luo Yuan , Yobas Levent , Chen Kevin J. 
Published: August 2012

AbstractDielectrophoresis (DEP) induced by activating a patterned two‐dimensional electron gas (2DEG) at the interface of compound semiconductor AlGaN/GaN heterojunction has been demonstrated for the first time in our previous work. Briefly, with a peak voltage of ±10 V and a frequency from 100 kHz to 1 MHz, characteristics of both positive and negative DEP have been observed successfully manipulating 2 µm polystyrene microspheres in a drop of deionized (DI) water (pH ∼ 7 and conductivity 1 × 10−4 S m−1) over castellated 2DEG electrodes separated by critical dimensions 50 and 150 µm. This study reports a peculiar observation encountered when performing the DEP experiments under ultraviolet (UV) radiation: The microspheres have been repelled from the 2DEG electrodes yet remained on the surface during pDEP and then levitated upon switching to nDEP. This behavior is not observed in DEP with conventional microelectrodes and explained here by the UV‐induced electron–hole generation and the subsequent charge redistribution in the AlGaN/GaN heterostructure.
Structural and optical properties of crystalline silicon thin films deposited on porous alumina
Authors: Ktifa S. , Ghrib M. , Saadallah F. , Yacoubi N. 
Published: August 2012

AbstractThe goal of this work is to investigate the influence of the anodization current on the optical properties of porous alumina layer, on which crystalline silicon films are deposited by a PECVD technique. Porous alumina layers were grown by a simple electrochemical anodization method, varying the anodizing voltage between 200 to 400 mV.The structural properties of the Si/Al2O3 films were studied by using Raman spectroscopy and XRD. Photothermal deflection spectroscopy (PDS) is used to determine the gap energy and the optical absorption spectrum by comparing the experimental amplitude of the photothermal signal to the corresponding theoretical one (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A detailed investigation on the failure mechanisms for IGBTs under successive short‐circuit conditions
Authors: Benbahouche Ly. , Merabet A. , Zegadi A. 
Published: August 2012

AbstractThe increasing demand in terms of device performance and reliability requires continuous developments of power semiconductors that operate under hard switching conditions SOA (Safe Operating Area). The aim of this paper to enable a better understanding of the main problems that are associated with successive short circuit failure modes like (latch up and second breakdown) and also to clarify the correlation with respect to the circuit elements. It investigates the temperature impact of successive short‐circuit delay time effects on the failure mechanisms evolutions and to evaluates the feasibility and issues of IGBT under successive short‐circuit conditions. The device behaviour can predicted at critical operations such as its latch up during a turn off short circuit condition or if there is an observable aging effect. It is shown that when applied to IXGH‐IGBT at its worst short circuit condition (successive short circuit), this one can work securely without affecting the normal system operation at higher temperatures. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DFT study of the effect of hydrostatic pressure on formation and migration enthalpies of intrinsic point defects in single crystal Si
Authors: Sueoka Koji , Kamiyama Eiji , Kariyazaki Hiroaki , Vanhellemont Jan 
Published: August 2012

AbstractThe dependence of the formation enthalpy (Hf) of the self‐interstitial I and the vacancy V on the hydrostatic pressure P was obtained by calculating the formation energy (Ef) and the relaxation volume (vf). The dependence of the migration enthalpy (Hm) of I and V on the pressure P was also obtained by calculating the change of Hf during the migration. Density functional theory calculations were used with 216‐atom supercells and with special attention for the convergence of the calculations. The neutral I and V are found to have quasi constant formation energies EfI and EfV for pressures between – 1 GPa to 1 GPa. For the relaxation volume, vfI is almost constant while vfV decreases with increasing pressure P. The formation and migration enthalpies HfI and HmI, respectively, at the [110] dumbbell site are given by HfI = 3.425 – 0.055×P (eV) and HmI = 0.981 – 0.039×P (eV) with hydrostatic pressure P given in GPa. The HfV and HmV dependencies on P are given by HfV =3.543 – 0.024×P2– 0.009×P (eV) and HmV = 0.249 + 0.005×P2 – 0.030×P (eV). These results indicate that hydrostatic pressure leads to a slight increase of the equilibrium concentration and diffusion of vacancies but this increase is considerably smaller than that of self‐interstitials (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect generation by argon implantation: microscopy characterization and electrical properties
Authors: Mica Isabella , Polignano Maria Luisa , Codegoni Davide , Mauri Aurelio , Soncini Valter 
Published: August 2012

AbstractIn this work defects generated by argon implantation were studied both by Transmission Electron Microscopy (TEM) inspections and by measurements of the defect electrical activity at the oxide‐silicon interface and in the bulk. TEM analyses showed defects close to the surface for argon doses equal or larger than 1013cm‐2, and stacking faults in the sample implanted with 1015 cm‐2 dose. The maximum defect depth was about 50 nm. The generation lifetime was heavily degraded even with the lowest argon dose. Besides, positive charge and a relevant population of interface states were found to be related to argon implantation. In addition, DLTS revealed four deep levels starting with the samples implanted with 1013cm‐2 argon dose. These levels evolve with increasing the argon dose and are located much deeper than the defects revealed by TEM, i.e. down to a few micron depth. The dependence of the signal amplitude on the filling pulse width was analyzed, and showed that all the observed levels are related to extended defects. Kinetic Monte Carlo simulations of the implantation and annealing process indicate that argon atoms interact with implantation‐induced defects and enhance the formation of extended defects. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)