bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the forecasting accuracy of multivariate GARCH models
Authors: Laurent Sébastien , Rombouts Jeroen V. K. , Violante Francesco 
Published: April 2011

SUMMARYThis paper addresses the question of the selection of multivariate generalized autoregressive conditional heteroskedastic (GARCH) models in terms of variance matrix forecasting accuracy, with a particular focus on relatively large‐scale problems. We consider 10 assets from the New York Stock Exchange and compare 125 models based 1‐, 5‐ and 20‐day‐ahead conditional variance forecasts over a period of 10 years using the model confidence set (MCS) and the superior predictive ability (SPA) tests. Model performance is evaluated using four statistical loss functions which account for different types and degrees of asymmetry with respect to over‐/under‐predictions. When considering the full sample, MCS results are strongly driven by short periods of high market instability during which multivariate GARCH models appear to be inaccurate. Over relatively unstable periods, i.e. the dot‐com bubble, the set of superior models is composed of sophisticated specifications such as orthogonal and dynamic conditional correlation (DCC), both with leverage effect in the conditional variances. However, unlike the DCC models, our results show that the orthogonal specifications tend to underestimate the conditional variance. Over calm periods, a simple assumption like constant conditional correlation and symmetry in the conditional variances cannot be rejected. Finally, during the 2007–2008 financial crisis, accounting for non‐stationarity in the conditional variance process generates superior forecasts. The SPA test suggests that, independently from the period, the best models do not provide significantly better forecasts than the DCC model of Engle (2002,Journal of Business and Economic Statistics20: 339–350) with leverage in the conditional variances of the returns. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and biological activities of a novel series of 3,6‐disubstituted‐1,2,4‐triazolo‐[3,4‐b]‐1,3,4‐thiadiazoles containing gem‐dimethylbenzyl moiety
Authors: Puthiyapurayil Pushpan , Poojary Boja , Kumar Sunil , Hunnur Raveendra 
Published: April 2011

AbstractA novel series of 3,6‐disubstituted‐1,2,4‐triazolo‐[3,4‐b]‐1,3,4‐thiadiazoles (6a–r) containing gem‐dimethyl benzyl moiety were prepared by the condensation of 4‐amino‐3‐aryl/aralkyl substituted‐5‐mercapto‐1,2,4‐triazoles (5a, 5b, 5c) with various fluoro substituted aromatic acids in the presence of POCl3. IR, 1H NMR, 13C NMR, 2D NMR (COSY), and mass spectral data confirmed the structures of all the synthesized compounds. All the compounds were also screened for their antibacterial, antifungal and analgesic activities. Compounds 6b, 6d, 6f, 6g, 6h, 6i, 6m, 6n, 6o, 6p, and 6r exhibited promising antibacterial and compounds 6a, 6d, 6f, 6g, 6h, 6k, 6m, 6o, 6p, and 6q showed significant analgesic activities. J. Heterocyclic Chem., (2011)
A convenient synthesis of pyrrolo‐annelated 1,3‐diselenole‐2‐thione and 1,3‐diselenol‐2‐one derivatives via dipyrrolo‐annelated 1,2,5,6‐tetraselenocine derivatives
Authors: Park Joon Bum , Kim Ja Hong , Zong Kyukwan 
Published: April 2011

AbstractThe reaction of 2,5‐dimethyl‐3,4‐diselenocyanato‐1H‐pyrrole by NaBH4 or NaOCH3 led to tetraselenide 7 in quantitative yield. Treatment of protected tetraselenide 8 with LiAlH4 afforded the aluminum complex intermediate that was converted into pyrrole‐annelated 1,3‐diselenolo‐2‐thione 9 in excellent yield. Similarly, treatment of tetraselenide 8 with LiAlH4 followed by TFA afforded 1,2‐diselenol intermediate that was converted into pyrrole‐annelated 1,3‐diselenolo‐2‐one 10 upon treatment of diimidazole carbonate. J. Heterocyclic Chem., (2011).
Transcription and pathway analysis of the superior temporal cortex and anterior prefrontal cortex in schizophrenia
Authors: Barnes Michael R. , Huxley‐Jones Julie , Maycox Peter R. , Lennon Mark , Thornber Amy , Kelly Fiona , Bates Stewart , Taylor Adam , Reid Juliet , Jones Neil , Schroeder Jörn , Scorer Carol A. , Davies Ceri , Hagan Jim J. , Kew James N.C. , Angelinetta Claire , Akbar Tariq , Hirsch Steven , Mortimer Ann M. , Barnes Thomas R.E. , de Belleroche Jackie 
Published: April 2011

AbstractThe molecular basis of schizophrenia is poorly understood; however, different brain regions are believed to play distinct roles in disease symptomology. We have studied gene expression in the superior temporal cortex (Brodmann area 22; BA22), which may play a role in positive pathophysiology, and compared our results with data from the anterior prefrontal cortex (BA10), which shows evidence for a role in negative symptoms. Genome‐wide mRNA expression was determined in the BA22 region in 23 schizophrenics and 19 controls and compared with a BA10 data set from the same subjects. After adjustments for confounding sources of variation, we carried out GeneGO pathway enrichment analysis in each region. Significant differences were seen in age‐related transcriptional changes between the BA22 and the BA10 regions, 21.8% and 41.4% of disease‐associated transcripts showing age association, respectively. After removing age associated changes from our data, we saw the highest enrichment in processes mediating cell adhesion, synaptic contact, cytoskeletal remodelling, and apoptosis in the BA22 region. For the BA10 region, we observed the strongest changes in reproductive signalling, tissue remodelling, and cell differentiation. Further exploratory analysis also identified potentially disease‐relevant processes that were undetected in our more stringent primary analysis, including autophagy in the BA22 region and the amyloid process in the BA10 region. Collectively, our analysis suggests disruption of many common pathways and processes underpinning synaptic plasticity in both regions in schizophrenia, whereas individual regions emphasize changes in certain pathways that may help to highlight pathway‐specific therapeutic opportunities to treat negative or positive symptoms of the disease. © 2011 Wiley‐Liss, Inc.
Seasonal anomalous rainfall in the central and eastern Amazon and associated anomalous oceanic and atmospheric patterns
Authors: Andreoli Rita Valéria , Ferreira de Souza Rodrigo Augusto , Kayano Mary Toshie , Candido Luiz Antônio 
Published: April 2011

AbstractPrevious papers have shown that the rainfall anomalies over the Amazon region result from the independent or combined effects of the eastern tropical Pacific and Atlantic Basins. Here, the monthly rainfall data of Itaituba, Manaus, Parintins, and Santarém for the 1931–1996 period has been used to classify its dry and rainy seasons into dry, very dry, wet, and very wet categories. The sea surface temperature (SST) and sea level pressure (SLP) patterns associated with these climate conditions in the central and eastern Amazon are discussed in terms of the relative influence of the tropical Atlantic and Pacific sectors, as well as their seasonal differences. These seasonal differences are, in part, determined by the seasonal phase locking of the El Niño‐Southern Oscillation (ENSO) and Atlantic equatorial modes. The rainy season cases are mostly driven by the ENSO and the inter‐hemispheric SST gradient mode in the tropical Atlantic, and the dry season cases, by the Atlantic equatorial mode (AEM). A new result here is the role of the inter‐Pacific‐Atlantic anomalous SST gradient mode on the rainfall anomalies. This mode acts concordantly with the Atlantic modes on the rainfall over the central and eastern Amazon, and is responsible for precipitation extreme cases during the dry season and for the very wet rainy season case. In other words, the intense inter‐Pacific‐Atlantic mode for these cases is the differential factor in relation to the moderate cases. The results here, especially in relation to the role of the inter‐Pacific‐Atlantic gradient in the central and eastern Amazon precipitation, have not been discussed before and should be taken into consideration in the diagnostic activities. Copyright © 2011 Royal Meteorological Society
Summer night‐time temperature trends on the Iberian Peninsula and their connection with large‐scale atmospheric circulation patterns
Authors: Sanchez‐Lorenzo Arturo , Pereira Paulo , Lopez‐Bustins Joan A. , Lolis Christos J. 
Published: April 2011

AbstractThe present paper studies the variability and trends of Tropical Nights (>20 °C) (TNs) on the Iberian Peninsula (IP) over the 1961–2007 period during the extended summer (defined as June, July, August, and September, JJAS). The analyses were performed with the mean series calculated for the whole IP and for different subregions. We conducted a regionalisation by means of a S‐Mode Principal Component Analysis (PCA), which identified three subregions where the variability of TNs behaves similarly: the Mediterranean (M) region, the centre‐north of the Peninsula (CN) region, and the Atlantic (A) region. Throughout the entire period, the mean summer TN series for the whole IP shows a significant increase; there are, however, some regional differences, as the CN and M regions present higher rates of warming than the A region. Using Canonical Correlation Analysis (CCA) we detected the large‐scale atmospheric circulation patterns controlling the interannual variability of TNs over the IP. The occurrence of TNs in the M and CN subregions is highly dependent on anticyclonic conditions over Western Europe in the mid‐troposphere level. The increase in the positive phase of this canonical mode during the last three decades might explain part of the positive trend of the TNs detected in summer on the IP. Copyright © 2011 Royal Meteorological Society
Statistical analysis of freezing temperatures in Central and Southern Florida
Authors: Waylen Peter R. 
Published: April 2011

AbstractThe probability distributions of the number of freezing periods per year, their timing and severity are examined at 25 stations in southern and central Florida. The proposed distributions, derived from stochastic crossing theory, provide adequate fits with the exception of three variables at different stations. The estimated parameter values reflect the changing geography of the freeze hazard. The freeze variable that exhibits the greatest variability over the area appears to be the number of periods, while the average severity of freezes and their timings are fairly homogeneous. The theoretical basis of the method permits estimation of the distribution of the dates of first and last freezes and the distribution of the coldest temperature likely to be encountered during any period of interest. The risks of periods of extremely cold temperatures, rarely observed in the historic records, may also be obtained from those at the more commonly encountered level. The technique provides a thorough yet easily interpreted summary of cold‐spell risks at any location.
The role of radiation geometry in the climate response of mount kenya's glaciers, part 2: Sloping versus horizontal surfaces
Authors: Hastenrath Stefan , Kruss Phillip D. 
Published: April 2011

AbstractThis part of the study expands the modelling of incident solar radiation on Mount Kenya and its glaciers to include the behaviour for sloping as compared to horizontal surfaces. It is concluded that for the purposes of the ongoing climate study the broad‐scale generalizations reached in part 1 of the study for horizontal reference surfaces remain inviolate for sloping reference surfaces. However, significant additional information is brought out by reference to sloping surfaces. Further, differences in absolute radiation magnitudes are significant for realistic situations of cloudiness and shading when modelling short‐term (e.g. monthly) radiation means. In the annual case, these differences are small for glaciers having mean gradients up to 45°; for the one extremely steep glacier with mean slope approaching 60°, these differences are significant. It is anticipated that for higher latitudes the discrepancies between sloping and horizontal reference surfaces in the annual case may well be more substantial. For Mount Kenya, located as it is almost directly under the Equator, it must be concluded that the conventional horizontal reference surface is indeed appropriate for climatic heat and mass budget analyses.
Role of trabecular microarchitecture in the formation, accumulation, and morphology of microdamage in human cancellous bone
Authors: Karim Lamya , Vashishth Deepak 
Published: April 2011

AbstractAlterations in microdamage morphology and accumulation are typically attributed to impaired remodeling, but may also result from changes in microdamage initiation and propagation. Such alterations are relevant for cancellous bone with high metabolic activity and numerous bone quality changes. This study investigates the role of trabecular microarchitecture on morphology and accumulation of microdamage in human cancellous bone. Trabecular bone cores from donors of varying ages and bone volume fraction (BV/TV) were separated into high and low BV/TV groups. Samples were subjected to no load or uniaxial compression to 0.6% (pre‐yield) or 1.1% (post‐yield) strain. Microdamage was stained with lead uranyl acetate and specimens were imaged via microcomputed tomography to quantify microdamage and determine its morphology in three‐dimensions (3D). Donors with high BV/TV had greater post‐yield strain and were tougher than low BV/TV donors. High BV/TV bone had less microdamage than low BV/TV bone under post‐ but not pre‐yield loading. Microdamage under both loading conditions showed significant correlations with microarchitecture and BV/TV, but the key predictor was structure model index (SMI). As SMI increased (more trabecular rods), microdamage morphology became crack‐like. Thus, low BV/TV and increased SMI have strong influences on microdamage accumulation in bone through altered initiation. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1739–1744, 2011
Long‐term survival after esophagectomy for early esophageal squamous cell carcinoma in Linxian, China
Authors: Song Philip I. , Liang Hao , Fan Jin‐Hu , Wei Wen‐Qiang , Wang Guo‐Qing , Qiao You‐Lin 
Published: April 2011

AbstractBackground and ObjectivesLinxian in Henan Province, China, has among the highest rates of esophageal cancer worldwide. Little is known about long‐term survival after esophagectomy for early neoplastic lesions found during early detection screening. A long‐term survival analysis was performed for 315 patients from Linxian who received esophagectomy for early esophageal squamous cell carcinoma (ESCC).MethodsCases that received esophagectomy for early ESCC were age‐ and gender‐matched with two healthy controls, and Kaplan–Meier survival analyses were performed for both groups.ResultsTen‐year survival was 77% for cases and 64% for controls, and this difference was not statistically significant (P = 0.33). There were no significant differences in survival based on age or gender (P > 0.05). Cases with ESCC in situ had significantly better survival than cases with invasive ESCC (P = 0.035).ConclusionsSurvival of cases who received esophagectomy for early ESCC was not significantly different from survival of age‐ and gender‐matched controls. Early intervention probably improved survival rates for these patients who otherwise would most likely have developed advanced esophageal carcinoma. Early screening and intervention are highly relevant in areas with a high risk of esophageal cancer such as Linxian, China. J. Surg. Oncol. 2011;104:176–180. © 2011 Wiley‐Liss, Inc.
Experimental design applied to the analysis of volatile compounds in apple juice by headspace solid‐phase microextraction
Authors: Llorente Daniel Díaz , Abrodo Pilar Arias , de la Fuente Enrique Dapena , Álvarez Jaime González , Álvarez Maria Dolores Gutiérrez , Gomis Domingo Blanco 
Published: April 2011

AbstractA simple and fast method based on solid‐phase microextraction (SPME) followed by fast gas chromatography (Fast GC) has been developed for the analysis of volatile compounds in Asturian apple juices employed in the cider production. Three different fiber coatings have been checked (PDMS, PDMS‐DVB and CAR‐PDMS) and PDMS‐DVB has been presented to be the most suitable one. Experimental design has been employed in the optimization of extraction factors and robustness assessment. The use of Fast GC allowed the separation of 14 compounds (esters, aldehydes and alcohols) in approximately 4 min, clearly reducing the analysis time when compared to conventional GC. Good linearity, recoveries and repeatability of the solid‐phase microextraction were obtained with r2 values, recoveries and relative standard deviations ranging from 0.9822 to 0.9998, 83.2 to 109.8% and 0.5 to 11.7%, respectively, using standard solution.
Mixed aqueous solutions as dilution media in the determination of residual solvents by static headspace gas chromatography
Authors: D'Autry Ward , Zheng Chao , Wolfs Kris , Yarramraju Sitaramaraju , Hoogmartens Jos , Van Schepdael Ann , Adams Erwin 
Published: April 2011

AbstractStatic headspace (HS) sampling has been commonly used to test for volatile organic chemicals, usually referred to as residual solvents (RS) in pharmaceuticals. If the sample is not soluble in water, organic solvents are used. However, these seriously reduce the sensitivity in the determination of some RS. Here, mixed aqueous dilution media (a mixture of water and an organic solvent like dimethyl formamide, dimethyl sulfoxide or dimethyl acetamide) were studied as alternative media for static HS‐gas chromatographic analysis. Although it has been known that mixed aqueous dilution media can often improve sensitivity for many RS, this study used a systematic approach to investigate phase volumes and the organic content in the HS sampling media. Reference solutions using 18 different class 1, 2 and 3 RS were evaluated. The effect of salt addition was also studied in this work. A significant increase in the peak area was observed for all RS using mixed aqueous dilution media, when compared with organic solvents alone. Matrix effects related to the mixed aqueous dilution media were also investigated and reported. Repeatability and linearity obtained with mixed aqueous dilution media were found to be similar to those observed with pure organic solvents.
Validated dispersive liquid–liquid microextraction for analysis of organophosphorous pesticides in water
Authors: Alves Andreia Cristina Henriques , Gonçalves Maria Margarida Pontes Boavida , Bernardo Maria Manuel Serrano , Mendes Benilde Simões 
Published: April 2011

AbstractDispersive liquid–liquid microextraction (DLLME) combined with gas chromatography and mass spectrometry (GC‐MS) was applied to the determination of six organophosphorous pesticides (OPPs) in water samples. The analytes included in this study were prophos, diazinon, chlorpyrifos methyl, methyl parathion, fenchlorphos and chlorpyrifos. Several extraction and dispersion solvents were tested for dispersive liquid–liquid microextraction of these analytes and the best results were obtained using chloroform as extraction solvent and 2‐propanol as dispersion solvent. Calibration curves of the analytes in water samples were constructed in the concentration range from 100 to 1100 ng/L for prophos, diazinon and methyl parathion and in the range from 100 to 1000 ng/L for chlorpyrifos methyl, fenchlorphos and chlorpyrifos. Limits of detection (LODs) were in the range of 1.5–9.1 ng/L and limits of quantification (LOQs) were in the range of 5.1–30.3 ng/L, below the maximum admissible level for drinking water. Relative standard deviations (RSDs) were between 6.5 and 10.1% in the concentration range of 100–1000 ng/L. The relative recoveries (%RRs) of tap, well and irrigation water samples fortified at 800 ng/L were in the range of 46.1–129.4%, with a larger matrix effect being detected in tap water.
Antibiotic prophylaxis in uncontaminated neck dissection
Authors: Man Li‐Xing , Beswick Daniel M. , Johnson Jonas T. 
Published: April 2011

AbstractObjectives/Hypothesis:To describe our institution's experience with antibiotic prophylaxis in uncontaminated neck dissection and to identify risk factors associated with postoperative wound infection.Study Design:Retrospective chart review.Methods:Between April 2006 and June 2010, 244 patients underwent 273 uncontaminated neck dissections at a single tertiary care center. Patient factors, operative details, and postoperative complications were recorded. Patients were separated into three groups: no prophylactic antibiotics, intraoperative antibiotics only, and intra‐ and postoperative antibiotics.Results:Wound infections occurred after nine of the 273 procedures (3.3%). All of the wound infections occurred in patients receiving intraoperative antibiotics only (4 of 157) or intra‐ and postoperative antibiotics (5 of 75) (P = .11). The development of a wound infection was not associated with age, sex, history of tobacco and alcohol use, history of head and neck surgery, or history of radiation or chemotherapy. Wound infection was independently associated with operative time (adjusted odds ratio, 1.35; 95% confidence interval, 1.07–1.71; P = .011, for each additional hour of surgery) and with radical or extended neck dissection (adjusted odds ratio, 14.61; 95% confidence interval, 2.37–90.01, P = .004).Conclusions:Our data did not support the use of antibiotic prophylaxis in routine uncontaminated neck dissection. Prophylactic antibiotics, however, may be indicated for more extensive lymphadenectomy procedures.
Temporal bone histopathology in neurofibromatosis type 2
Authors: Nam Sung‐Il , Linthicum Fred H. , Merchant Saumil N. 
Published: April 2011

AbstractObjectives/Hypothesis:To describe the histopathologic findings in the temporal bone in patients with neurofibromatosis type 2 (NF2). The literature contains limited data on otopathology of NF2.Study Design:Basic science study.Methods:Twenty‐six temporal bones from 16 patients with NF2 were examined by light microscopy. The diagnosis of NF2 was made on the basis of bilateral cochleovestibular schwannomas. Clinical information was obtained from review of the medical records.Results:The tumors were multicentric in origin in 19 of 26 (73%) ears. Typically, tumors were seen arising within the internal auditory canal and from various locations within the labyrinth. The majority of schwannomas showed high cellularity with involvement of the labyrinth. Most cases showed significant degrees of degeneration of sensory and neural elements within the cochlea. Fusion tumors were sometimes seen as a result of a schwannoma merging with an adjacent meningioma. Fifteen of 26 (58%) ears showed facial nerve involvement by schwannoma.Conclusions:Cochleovestibular schwannomas in NF2 are aggressive neoplasms; they are often multicentric and demonstrate a propensity to involve the labyrinth. There is often associated secondary degeneration within the cochlea. These features make total removal of these tumors and their removal with preservation of hearing more difficult than with sporadic unilateral cochleovestibular schwannoma.