bluuebunny/crossref_metadata_2025_split huggingface dataset:
A POD reduced‐order 4D‐Var adaptive mesh ocean modelling approach
Authors: Fang F. , Pain C. C. , Navon I. M. , Piggott M. D. , Gorman G. J. , Farrell P. E. , Allison P. A. , Goddard A. J. H. 
Published: September 2008

AbstractA novel proper orthogonal decomposition (POD) inverse model, developed for an adaptive mesh ocean model (the Imperial College Ocean Model, ICOM), is presented here. The new POD model is validated using the Munk gyre flow test case, where it inverts for initial conditions. The optimized velocity fields exhibit overall good agreement with those generated by the full model. The correlation between the inverted and the true velocity is 80–98% over the majority of the domain. Error estimation was used to judge the quality of reduced‐order adaptive mesh models. The cost function is reduced by 20% of its original value, and further by 70% after the POD bases are updated.In this study, the reduced adjoint model is derived directly from the discretized reduced forward model. The whole optimization procedure is undertaken completely in reduced space. The computational cost for the four‐dimensional variational (4D‐Var) data assimilation is significantly reduced (here a decrease of 70% in the test case) by decreasing the dimensional size of the control space, in both the forward and adjoint models. Computational efficiency is further enhanced since both the reduced forward and adjoint models are constructed by a series of time‐independent sub‐matrices. The reduced forward and adjoint models can be run repeatedly with negligible computational costs.An adaptive POD 4D‐Var is employed to update the POD bases as minimization advances and loses control, thus adaptive updating of the POD bases is necessary. Previously developed numerical approaches Fang et al. (Int. J. Numer. Meth. Fluids 2008) are employed to accurately represent the geostrophic balance and improve the efficiency of the POD simulation. Copyright © 2008 John Wiley & Sons, Ltd.
The information content in implied idiosyncratic volatility and the cross‐section of stock returns: Evidence from the option markets
Authors: Diavatopoulos Dean , Doran James S. , Peterson David R. 
Published: September 2008

AbstractCurrent literature is inconclusive as to whether idiosyncratic risk influences future stock returns and the direction of the impact. Earlier studies are based on historical realized volatility. Implied volatilities from option prices represent the market's assessment of future risk and are likely a superior measure to historical realized volatility. Implied idiosyncratic volatilities on firms with traded options are used to examine the relationship between idiosyncratic volatility and future returns. A strong positive link was found between implied idiosyncratic risk and future returns. After considering the impact of implied idiosyncratic volatility, historical realized idiosyncratic volatility is unimportant. This performance is strongly tied to small size and high book‐to‐market equity firms. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28: 1013–1039, 2008
The economic value of volatility transmission between the stock and bond markets
Authors: Chuliá Helena , Torró Hipòlit 
Published: September 2008

AbstractThis study has two main objectives. Firstly, volatility transmission between stocks and bonds in European markets is studied using the two most important financial assets in these fields: the DJ Euro Stoxx 50 index futures contract and the Euro Bund futures contract. Secondly, a trading rule for the major European futures contracts is designed. This rule can be applied to different markets and assets to analyze the economic significance of volatility spillovers observed between them. The results indicate that volatility spillovers take place in both directions and that the stock‐bond trading rule offers very profitable returns after transaction costs. These results have important implications for portfolio management and asset allocation. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28:1066–1094, 2008
Dynamic hedging with futures: A copula‐based GARCH model
Authors: Hsu Chih‐Chiang , Tseng Chih‐Ping , Wang Yaw‐Huei 
Published: September 2008

AbstractIn a number of earlier studies it has been demonstrated that the traditional regression‐based static approach is inappropriate for hedging with futures, with the result that a variety of alternative dynamic hedging strategies have emerged. In this study the authors propose a class of new copula‐based GARCH models for the estimation of the optimal hedge ratio and compare their effectiveness with that of other hedging models, including the conventional static, the constant conditional correlation (CCC) GARCH, and the dynamic conditional correlation (DCC) GARCH models. With regard to the reduction of variance in the returns of hedged portfolios, the empirical results show that in both the in‐sample and out‐of‐sample tests, with full flexibility in the distribution specifications, the copula‐based GARCH models perform more effectively than other dynamic hedging models. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28:1095–1116, 2008
Stratigraphic and structural evolution of the Blue Nile Basin, Northwestern Ethiopian Plateau
Authors: Gani N. DS. , Abdelsalam M. G. , Gera S. , Gani M. R. 
Published: September 2008

AbstractThe Blue Nile Basin, situated in the Northwestern Ethiopian Plateau, contains ∼1400 m thick Mesozoic sedimentary section underlain by Neoproterozoic basement rocks and overlain by Early–Late Oligocene and Quaternary volcanic rocks. This study outlines the stratigraphic and structural evolution of the Blue Nile Basin based on field and remote sensing studies along the Gorge of the Nile. The Blue Nile Basin has evolved in three main phases: (1) pre‐sedimentation phase, include pre‐rift peneplanation of the Neoproterozoic basement rocks, possibly during Palaeozoic time; (2) sedimentation phase from Triassic to Early Cretaceous, including: (a) Triassic–Early Jurassic fluvial sedimentation (Lower Sandstone, ∼300 m thick); (b) Early Jurassic marine transgression (glauconitic sandy mudstone, ∼30 m thick); (c) Early–Middle Jurassic deepening of the basin (Lower Limestone, ∼450 m thick); (d) desiccation of the basin and deposition of Early–Middle Jurassic gypsum; (e) Middle–Late Jurassic marine transgression (Upper Limestone, ∼400 m thick); (f) Late Jurassic–Early Cretaceous basin‐uplift and marine regression (alluvial/fluvial Upper Sandstone, ∼280 m thick); (3) the post‐sedimentation phase, including Early–Late Oligocene eruption of 500–2000 m thick Lower volcanic rocks, related to the Afar Mantle Plume and emplacement of ∼300 m thick Quaternary Upper volcanic rocks. The Mesozoic to Cenozoic units were deposited during extension attributed to Triassic–Cretaceous NE–SW‐directed extension related to the Mesozoic rifting of Gondwana. The Blue Nile Basin was formed as a NW‐trending rift, within which much of the Mesozoic clastic and marine sediments were deposited. This was followed by Late Miocene NW–SE‐directed extension related to the Main Ethiopian Rift that formed NE‐trending faults, affecting Lower volcanic rocks and the upper part of the Mesozoic section. The region was subsequently affected by Quaternary E–W and NNE–SSW‐directed extensions related to oblique opening of the Main Ethiopian Rift and development of E‐trending transverse faults, as well as NE–SW‐directed extension in southern Afar (related to northeastward separation of the Arabian Plate from the African Plate) and E–W‐directed extensions in western Afar (related to the stepping of the Red Sea axis into Afar). These Quaternary stress regimes resulted in the development of N‐, ESE‐ and NW‐trending extensional structures within the Blue Nile Basin. Copyright © 2008 John Wiley & Sons, Ltd.
Undiagnosed sleep‐related breathing disorders are associated with focal brainstem atrophy in the elderly
Authors: Celle Sébastien , Peyron Roland , Faillenot Isabelle , Pichot Vincent , Alabdullah Majed , Gaspoz Jean‐Michel , Laurent Bernard , Barthélémy Jean‐Claude , Roche Frédéric 
Published: September 2008

AbstractBackground: Sleep‐related breathing disorders (SRBDs) affect as many as 40% of elderly people. The association of SRBDs with structural brain abnormalities remains unclear. In this observational study, we evaluated gray matter changes in the brain associated with sleep abnormalities in volunteers and their relationship with the severity of SRBDs. Methods: One hundred fifty two healthy subjects aged 66.0 ± 0.6 years‐old underwent tridimensional brain MRI and nocturnal polygraphic recording during which apnea/hypopnea index (AHI) and the oxyhemoglobin desaturation index (ODI) were measured. Using voxel‐based morphometry, we investigated the presence of gray matter abnormalities in association with AHI and ODI. Findings: Seventy‐six subjects (50%) had SRBDs defined by an AHI ≥ to 15 and 25 subjects (16%) SRBDs defined by an ODI ≥ 15, in the absence of systematic excessive daytime sleepiness. A significant symmetrical loss of gray matter in the intermediate reticular zone of the bulbopontine area was found to correlate with both AHI and ODI (P < 0.05 corrected for multiple comparisons for cluster significance). Interpretation: This gray matter volume decrease in brain regions involved in breathing/autonomic functions, as well as their correlation with the severity of the disorder, suggests a pathophysiological link between structural changes and SRBDs. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
Regional networks underlying interhemispheric connectivity: An EEG and DTI study in healthy ageing and amnestic mild cognitive impairment
Authors: Teipel Stefan J. , Pogarell Oliver , Meindl Thomas , Dietrich Olaf , Sydykova Djyldyz , Hunklinger Ulrike , Georgii Bea , Mulert Christoph , Reiser Maximilian F. , Möller Hans‐Jürgen , Hampel Harald 
Published: September 2008

AbstractInterhemispheric coherence derived from electroencephalogram (EEG) recordings is a measure of functional interhemispheric connectivity. Diffusion tensor imaging (DTI) determines the integrity of subcortical fiber tracts. We studied the pattern of subcortical fiber tracts underlying interhemispheric coherence and its alteration in 16 subjects with amnestic mild cognitive impairment (MCI), an at risk syndrome for Alzheimer's disease, and 20 cognitively healthy elderly control subjects using resting state EEG and high resolution DTI at 3 T. We used a multivariate network approach based on principal component analysis to determine effects of coherence on the regional pattern of diffusivity. Temporo‐parietal coherence in the α band was significantly correlated with diffusivity in predominantly posterior white matter tracts including posterior corpus callosum, parietal, temporal and occipital lobe white matter, thalamus, midbrain, pons, and cerebellum, both in MCI subjects and controls (P < 0.05). In MCI subjects, frontal coherence in the α band was significantly correlated with a predominately frontal pattern of diffusivity including fiber tracts of the anterior corpus callosum, frontal lobe white matter, thalamus, pons, and cerebellum (P < 0.05). The study provides a methodology to access specific networks of subcortical fiber tracts subserving the maintenance of interhemispheric resting state coherence in the human brain. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
Instinctive modulation of cognitive behavior: A human evoked potential study
Authors: Nahum Louis , Morand Stéphanie , Barcellona‐Lehmann Sandra , Schnider Armin 
Published: September 2008

AbstractSuccessful adaptive behavior requires fast information processing. Behavioral switches may be necessary in response to threatening stimuli or when anticipated outcomes fail to occur. In this study, we explored the cortical processing of these two components using high‐resolution evoked potentials. Subjects made a reversal learning task where they had to predict which one of two faces had a target stimulus on the nose. We found early electrocortical differences at 100–200 ms depending on whether the target stimulus was a spider or a disk. Source estimation indicated that this distinction was mediated by an anterior medial temporal region including the amygdala and adjacent cortex. When a switch to the alternate face was required, there was a discrete early electrocortical correlate after 200 ms, mediated by ventromedial prefrontal areas. Continued validity of stimulus‐target associations was signaled at 400–520 ms, mediated by the parahippocampal region. The study indicates rapid serial processing of innate emotional quality, then cognitive‐behavioral relevance of stimuli, mediated by limbic and paralimbic structures. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
Characterization of a glycine N‐methyltransferase gene knockout mouse model for hepatocellular carcinoma: Implications of the gender disparity in liver cancer susceptibility
Authors: Liao Yi‐Jen , Liu Shih‐Ping , Lee Cheng‐Ming , Yen Chia‐Hung , Chuang Pei‐Chun , Chen Chia‐Yen , Tsai Ting‐Fen , Huang Shiu‐Feng , Lee Yan‐Hwa Wu , Chen Yi‐Ming Arthur 
Published: September 2008

AbstractHepatocellular carcinoma (HCC) is the fifth common cancer in the world and it mainly occurs in men. Glycine N‐methyltransferase (GNMT) participates in one‐carbon metabolism and affects DNA methylation by regulating the ratio of S‐adenosylmethionine to S‐adenosylhomocystine. Previously, we described that the expression of GNMT was diminished in human HCC. Here, we showed that 50% (3/6) male and 100% (7/7) female Gnmt−/− mice developed HCC, and their mean ages of HCC development were 17 and 16.5 months, respectively. In addition, 42.9% (3/7) of female Gnmt−/− mice had hemangioma. Wnt reporter assay demonstrated that Gnmt is a negative regulator for canonical Wnt signaling pathway. Beta‐catenin, cyclin D1 and c‐Myc, genes related to Wnt pathway, were upregulated in the liver tissues from both 11 weeks and HCC stage of Gnmt−/− mice. Furthermore, global DNA hypomethylation and aberrant expression of DNA methyltransferases 1 and 3b were found in the early and late stages of HCC development. Hierarchical cluster analysis of 6,023 transcripts from microarray data found that gene expression patterns of HCC tumors from male and female Gnmt−/− mice were distinctively different. Real‐time PCR confirmed that Gadd45a, Pak1, Mapk3 and Dsup3 genes of mitogen‐activated protein kinase (MAPK) pathway were activated in Gnmt−/− mice, especially in the female mice. Therefore, GNMT is a tumor suppressor gene for liver cancer, and it is associated with gender disparity in liver cancer susceptibility. © 2008 Wiley‐Liss, Inc.
Evaluation of molecular forms of prostate‐specific antigen and human kallikrein 2 in predicting biochemical failure after radical prostatectomy
Authors: Wenske Sven , Korets Ruslan , Cronin Angel M. , Vickers Andrew J. , Fleisher Martin , Scher Howard I. , Pettersson Kim , Guillonneau Bertrand , Scardino Peter T. , Eastham James A. , Lilja Hans 
Published: September 2008

AbstractMost pretreatment risk‐assessment models to predict biochemical recurrence (BCR) after radical prostatectomy (RP) for prostate cancer rely on total prostate‐specific antigen (PSA), clinical stage, and biopsy Gleason grade. We investigated whether free PSA (fPSA) and human glandular kallikrein‐2 (hK2) would enhance the predictive accuracy of this standard model. Preoperative serum samples and complete clinical data were available for 1,356 patients who underwent RP for localized prostate cancer from 1993 to 2005. A case‐control design was used, and conditional logistic regression models were used to evaluate the association between preoperative predictors and BCR after RP. We constructed multivariable models with fPSA and hK2 as additional preoperative predictors to the base model. Predictive accuracy was assessed with the area under the ROC curve (AUC). There were 146 BCR cases; the median follow up for patients without BCR was 3.2 years. Overall, 436 controls were matched to 146 BCR cases. The AUC of the base model was 0.786 in the entire cohort; adding fPSA and hK2 to this model enhanced the AUC to 0.798 (p= 0.053), an effect largely driven by fPSA. In the subgroup of men with total PSA ≤10 ng/ml (48% of cases), adding fPSA and hK2 enhanced the AUC of the base model to a similar degree (from 0.720 to 0.726,p= 0.2). fPSA is routinely measured during prostate cancer detection. We suggest that the role of fPSA in aiding preoperative prediction should be investigated in further cohorts. © 2008 Wiley‐Liss, Inc.
Imbalance of DNA‐dependent protein kinase subunits in polycythemia vera peripheral blood stem cells
Authors: Siebolts Udo , Breuhahn Kai , Hennecke Andrea , Schultze Joachim L. , Wickenhauser Claudia 
Published: September 2008

AbstractPolycythemia vera (PV) is a clonal hematopoietic stem cell disease characterized by a trilinear accumulation of blood cells that has been recently associated with a JAK2V617F point mutation. However, this molecular defect represents a rather late event in the disease progression, is not specific for this disease, and is not ascertained in all patients indicating that additional factors contribute to the specific phenotype of PV. Therefore, cDNA microarray analyses were performed on CD34+ peripheral blood stem cells (PBSC) with subsequent evaluation on mRNA and protein level of a larger cohort of PV patients. Microarray analyses revealed a significant dysregulation of 11 genes. KU86, a gene coding for a subunit of the DNA‐dependent protein kinase (DNA‐PK), displayed the strongest upregulation in all patients under study. This peculiarity was accompanied by downregulation of the catalytic DNA‐PK subunit DNA‐PKcs. Also Ku86 protein was upregulated and expressed in the vast majority of CD34+ PBSC nuclei while a weak nuclear expression was detected in only one blood donor. Differential expression of several genes, imbalance of the distinct subunits of DNA‐PK, and particularly the strong upregulation of Ku86 protein, are new findings in PV CD34+ PBSC. These factors may contribute to the accumulation of chromosomal aberrations, accumulation of hematopoietic cells (especially of erythropoiesis), and prolongation of CD34+ PBSC life span observed in PV. © 2008 Wiley‐Liss, Inc.
Cure of established GL261 mouse gliomas after combined immunotherapy with GM‐CSF and IFNγ is mediated by both CD8+ and CD4+ T‐cells
Authors: Smith Karin Enell , Fritzell Sara , Badn Wiaam , Eberstål Sofia , Janelidze Shorena , Visse Edward , Darabi Anna , Siesjö Peter 
Published: September 2008

AbstractWe were the first to demonstrate that combined immunotherapy with GM‐CSF producing GL261 cells and recombinant IFNγ of preestablished GL261 gliomas could cure 90% of immunized mice. To extend these findings and to uncover the underlying mechanisms, the ensuing experiments were undertaken. We hypothesized that immunizations combining both GM‐CSF and IFNγ systemically would increase the number of immature myeloid cells, which then would mature and differentiate into dendritic cells (DCs) and macrophages, thereby augmenting tumor antigen presentation and T‐cell activation. Indeed, the combined therapy induced a systemic increase of both immature and mature myeloid cells but also an increase in T regulatory cells (T‐regs). Cytotoxic anti‐tumor responses, mirrored by an increase in Granzyme B‐positive cells as well as IFNγ‐producing T‐cells, were augmented after immunizations with GM‐CSF and IFNγ. We also show that the combined therapy induced a long‐term memory with rejection of intracerebral (i.c.) rechallenges. Depletion of T‐cells showed that both CD4+ and CD8+ T‐cells were essential for the combined GM‐CSF and IFNγ effect. Finally, when immunizations were delayed until day 5 after tumor inoculation, only mice receiving immunotherapy with both GM‐CSF and IFNγ survived. We conclude that the addition of recombinant IFNγ to immunizations with GM‐CSF producing tumor cells increased the number of activated tumoricidal T‐cells, which could eradicate established intracerebral tumors. These results clearly demonstrate that the combination of cytokines in immunotherapy of brain tumors have synergistic effects that have implications for clinical immunotherapy of human malignant brain tumors. © 2008 Wiley‐Liss, Inc.
Causes of death among Belgian professional military radar operators: A 37‐year retrospective cohort study
Authors: Degrave Etienne , Meeusen Ben , Grivegnée André‐Robert , Boniol Mathieu , Autier Philippe 
Published: September 2008

AbstractConcerns have been raised about the safety of the electromagnetic (microwave) emissions of radars, as well as about the ionizing radiation that is emitted on short distances (<2 m) by devices in the radars producing the microwaves. We retrospectively compared the cause specific mortality of 4,417 Belgian professional male military personnel who served in anti‐aircraft radar units in Germany between 1963 and 1994 to the cause specific mortality of 2,932 Belgian military personnel who served at the same time in the same place in battalions not equipped with radars. Mean follow‐up was 26 years in the 2 groups. Age‐adjusted rate ratio (RR) and 95% confidence intervals were derived from a Poisson regression model. Four hundred twenty‐four deaths in the battalions groups and 271 deaths in the control battalions occurred (RR = 1.04 (0.96–1.14)). For specific causes of deaths, RRs were 1.22 (1.03–1.47) for neoplasms and 3.51 (1.19–10.3) for symptoms, signs and ill defined conditions. RRs for other causes of death were not significantly different from 1.00. Among deaths from neoplasms, RR for hemolymphatic cancer was 7.22 (1.09–47.9). RRs for other causes of cancer deaths were not significantly different from 1.00. The results for specific tumor types were all based on very small numbers. The RR for cancer increased with decreasing age and suggested that the RR for cancer increased with the duration of stay in radar battalions. In conclusion, exposure of professional military personnel to anti‐aircraft radars that existed in Western Europe from the 1960s until the 1990s may have resulted in an increase in the incidence of hemolymphatic cancers. It remains to be established whether this increase is due to microwaves generated by radars or ionizing radiation produced by electronic devices producing the microwaves. © 2008 Wiley‐Liss, Inc.