bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Observational Analysis and Evaluation of Land Surface Model Accuracy in the Nebraska Sand Hills
Authors: Radell David B. , Rowe Clinton M. 
Published: August 2008

Abstract
In this study, the influence of subsurface water on the energy budget components of three locations with heterogeneous land surfaces in the Nebraska Sand Hills are examined through observations and use of the Noah land surface model (LSM). Observations of the four primary components of the surface energy budget are compared for a wet interdunal meadow valley, a dry interdunal valley, and a dunal upland location. With similar atmospheric forcing at each site, it was determined that differences in the partitioning of the mean diurnal net radiation (Rnet) existed among the three locations due to the influence of varied soil moisture and vegetation through the year. At the wet valley, observations indicated that almost 65% of the mean daily peak Rnet was used for latent heating, due to the relatively higher soil moisture content resulting from an annual upward gradient of subsurface water and denser vegetation. In sharp contrast, the dunal upland site yielded only 21% of the mean daily peak Rnet going to latent heating, and a greater mean diurnal soil heat flux with typically drier soils and sparser vegetation than at the wet valley. The dry valley partition of the peak Rnet fell between the wet valley and dunal upland site, with approximately 50% going to sensible heating and 50% toward latent heating. In addition to the observational analysis, an uncoupled land surface model was forced with the observations from each site to simulate the energy budgets, with no tuning of the model’s fundamental equations and with little adjustment of the model parameters to improve results. While the model was able to reasonably simulate the mean diurnal and annual energy budget components at all locations, in most instances with root-mean-square errors within 20%–25% of the observed values, the lack of explicit treatment of subsurface water within the model limited predictability, particularly at the wet valley site. For instance, only 25% of the peak mean diurnal Rnet went toward latent heating in the model simulation of the wet valley, compared to 65% as estimated by observations. Model evaluation statistics are presented to document the land surface model’s ability to capture the annual and mean diurnal variations in the surface energy budget terms at the dry valley and dunal upland sites, but the absence of subsurface water results in large errors in the wet valley simulation. From these results, a case is made for the future inclusion of the explicit treatment of subsurface water within the Noah LSM to better approximate the prediction of the surface energy budget in such environments.
The Role of Local Moisture Recycling Evaluated Using Stable Isotope Data from over the Middle of the Tibetan Plateau during the Monsoon Season
Authors: Kurita Naoyuki , Yamada Hiroyuki 
Published: August 2008

Abstract
Both meteorological data and stable isotope data were used to investigate the role that local moisture recycling plays in maintaining moist land surface conditions over the middle of the Tibetan Plateau during the summer monsoon season. Past studies have shown that precipitation events of the summer monsoon season can be categorized according to synoptic conditions as east-migrating trough types, heat low types, and regional circulation types. Precipitation events during an intensive observation period from 13 to 27 August 2004 were therefore classified into these three types. The contributions of locally recycled moisture in each precipitation type were investigated using isotopic features. The isotope data include precipitation, near-surface atmospheric moisture, and evapotranspiration. First, using a simple Rayleigh distillation model, the isotopic content of the moisture source of the rainfall was estimated from observed precipitation isotope data. The contribution of lower-atmospheric moisture to the precipitation was then evaluated by comparing isotopic values. Next, when rainfall was mainly fed by lower-atmosperic moisture, the contribution of evapotranspirated water in the lower atmosphere was assessed by considering the factors controlling the isotopic variability of lower-atmospheric moisture. The results show that, in the case of trough-type rainfall, moisture flux convergence occurred in this area and a remarkable increase in precipitable water was observed when a trough approached the site. Thus, observed large isotopic variation associated with the passage of a trough reflects the isotopic content of moisture advected from the surrounding areas. With the exception of trough-type rainfall, the simulated isotopic values agreed well with the isotopic value of lower-atmospheric moisture. This finding indicates that lower-atmospheric moisture is the dominant source of such rainfall. In these periods, temporal isotopic variation in lower-atmospheric moisture showed gradual increases accompanied by an increased contribution of evapotranspirated water that had relatively heavy isotopic values. In particular, when the regional circulation type of rainfall was observed, the local recycling ratio, which is the contribution of locally evapotranspirated water in the boundary layer, increased from 30% to 80%. Locally recycled moisture thus plays an important role in precipitation associated with regional circulation. Active moisture recycling contributes to a high frequency of precipitation events so that the moist land surface is maintained during the summer monsoon period in this region.
A Preliminary Analysis of Spatial Variability of Raindrop Size Distributions during Stratiform Rain Events
Authors: Lee Choong Ke , Lee Gyu Won , Zawadzki Isztar , Kim Kyung-Eak 
Published: August 2008

Abstract
The spatial variability of raindrop size distributions (DSDs) and precipitation fields is investigated utilizing disdrometric measurements from the four Precipitation Occurrence Sensor Systems (POSS) and radar reflectivity fields from S-band dual-polarization radar and vertically pointing X-band radar. The spatial cross correlation of the moments of DSDs, their ratio, error in rainfall estimate, and normalization parameters are quantified using a “noncentered” correlation function. The time-averaged spatial autocorrelation function of observed radar reflectivity factor (Ze) is smaller than that of estimated rainfall rate from Ze because of power-law R–Z transformation with its exponent larger than unity. The important spatial variability of DSDs and rain integral fields is revealed by the significant differences among average DSDs and leads to an average fractional error of 25% in estimating rainfall accumulation during an event. The spatial correlation of the reflectivity from POSS is larger than that of Ze because of larger measurement noise in Ze. The higher moments of DSDs are less correlated in space than lower moments. The correlation of rainfall estimate error is higher than that of estimated rainfall rate and of rainfall rate calculated from DSDs. The correlation of the characteristic number density is low (0.87 at 1.3-km distance), suggesting that the assumed homogeneity of the characteristic number density in space could result in larger errors in the retrieval of DSDs and rain-related parameters. However, the characteristic diameter is highly correlated in space.
On the Summertime Strengthening of the Northern Hemisphere Pacific Sea Level Pressure Anticyclone
Authors: Nigam Sumant , Chan Steven C. 
Published: August 2008

Abstract
This study revisits the question posed by Hoskins on why the Northern Hemisphere Pacific sea level pressure (SLP) anticyclone is strongest and maximally extended in summer when the Hadley cell descent in the northern subtropics is the weakest. The paradoxical evolution is revisited because anticyclone buildup to the majestic summer structure is gradual, spread evenly over the preceding 4–6 months, and not just confined to the monsoon-onset period, which is interesting, as monsoons are posited to be the cause of the summer vigor of the anticyclone.
Anticyclone buildup is moreover found focused in the extratropics, not the subtropics, where SLP seasonality is shown to be much weaker, generating a related paradox within the context of the Hadley cell’s striking seasonality. Showing this seasonality to arise from, and thus represent, remarkable descent variations in the Asian monsoon sector, but not over the central-eastern ocean basins, leads to the resolution of this paradox.
Evolution of other prominent anticyclones is analyzed to critique the development mechanisms: the Azores high evolves like the Pacific one, but without a monsoon to its immediate west. The Mascarene high evolves differently, peaking in austral winter. Monsoons are not implicated in both cases.
Diagnostic modeling of seasonal circulation development in the Pacific sector concludes this inquiry. Of the three forcing regions examined, the Pacific midlatitudes are found to be the most influential, accounting for over two-thirds of the winter-to-summer SLP development in the extratropics (6–8 hPa), with the bulk coming from the abatement of winter storm-track heating and transients. The Asian monsoon contribution (2–3 hPa) is dominant in the Pacific (and Atlantic) subtropics.
The modeling results resonate with observational findings and attest to the demise of winter storm tracks as the principal cause of the summer vigor of the Pacific anticyclone.
Intercomparison of Methods for the Temporal Interpolation of Synoptic Wind Fields
Authors: Gorman Richard M. 
Published: August 2008

Abstract
The problem of temporal interpolation of wind fields is addressed by comparing the performance of standard linear interpolation with two methods that aim to provide a more accurate description of advecting weather systems: the complex empirical orthogonal function (EOF) method introduced by Zavala-Hidalgo and a method based on fast Fourier transform (FFT) techniques. Two test cases are considered. In the first, wind fields representing an idealized fast-moving tropical cyclone were interpolated. In this case, the FFT method provided root-mean-square errors approximately two-thirds of those from linear interpolation, while the EOF method produced larger errors than linear interpolation. The second test case, using one month of ECMWF analysis fields on a Southern Hemisphere regional domain, showed that the FFT method is insufficiently robust for complex wind fields with multiple moving weather systems. The EOF method, on the other hand, produced smaller errors than linear interpolation.
Singular Vector Structure and Evolution of a Recurving Tropical Cyclone
Authors: Kim Hyun Mee , Jung Byoung-Joo 
Published: August 2008

Abstract
In this study, the structure and evolution of total energy singular vectors (SVs) of Typhoon Usagi (2007) are evaluated using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) and its tangent linear and adjoint models with a Lanczos algorithm. Horizontal structures of the initial SVs following the tropical cyclone (TC) evolution suggest that, relatively far from the region of TC recurvature, SVs near the TC center have larger magnitudes than those in the midlatitude trough. The SVs in the midlatitude trough region become dominant as the TC passes by the region of recurvature. Increasing magnitude of the SVs over the midlatitude trough regions is associated with the extratropical transition of the TC. While the SV sensitivities near the TC center are mostly associated with warming in the midtroposphere and inflow toward the TC along the edge of the subtropical high, the SV sensitivities in the midlatitude are located under the upper trough with upshear-tilted structures and associated with strong baroclinicity and frontogenesis in the lower troposphere. Given the results in this study, sensitive regions for adaptive observations of TCs may be different following the TC development stage. Far from the TC recurvature, sensitive regions near TC center may be important. Closer to the TC recurvature, effects of the midlatitude trough become dominant and the vertical structures of the SVs in the midlatitude are basically similar to those of extratropical cyclones.
Baroclinic Transition of a Long-Lived Mesoscale Convective Vortex
Authors: Galarneau Thomas J. , Bosart Lance F. , Davis Christopher A. , McTaggart-Cowan Ron 
Published: August 2008

Abstract
The period 5–15 June 2003, during the field phase of the Bow Echo and Mesoscale Convective Vortex (MCV) Experiment (BAMEX), was noteworthy for the wide variety of mesoscale convective systems (MCSs) that occurred. Of particular interest was a long-lived MCV that formed in the trailing stratiform region of an MCS over west Texas at 0600 UTC 10 June. This MCV was noteworthy for its (i) longevity as it can be tracked from 0600 UTC 10 June to 1200 UTC 14 June, (ii) development of a surface cyclonic circulation and attendant −2- to −4-hPa sea level pressure perturbation, (iii) ability to retrigger convection and produce widespread rains over several diurnal heating cycles, and (iv) transition into a baroclinic surface cyclone with distinct frontal features. Baroclinic transition, defined here as the acquisition of surface fronts, occurred as the MCV interacted with a remnant cold front, left behind by a predecessor extratropical cyclone, over the Great Lakes region. Although the MCV developed well-defined frontal structure, which helped to focus heavy precipitation, weakening occurred throughout the baroclinic transition process. Energetics calculations indicated that weakening occurred as the diabatic and baroclinic energy conversion terms approached zero just prior and during baroclinic transition. This weakening can be attributed to (i) an increase in environmental wind shear, (ii) the development of a downshear tilt and associated anticyclonic vorticity advection over the surface low center, and (iii) the eastward relative movement of organized convection away from the MCV center.
Early relapses after the first dose of natalizumab in active multiple sclerosis patients
Authors: Centonze D , Furlan R , Gasperini C , Salvetti M , Battistini L 
Published: August 2008

Background Natalizumab is prescribed in Italy in patients who experienced at least two clinical relapses during a 12-month therapy with other approved immunomodulatory agents. Results In 7 of 35 patients selected on the basis of these recommendations, we have observed clinical relapses occurring within 24 h after the first dose of natalizumab. Conclusion The mechanism by which a first injection of natalizumab may precipitate a clinical relapse in patients with MS is unknown. We speculate that natalizumab can promote the release of inflammatory mediators from lymphocytes present in the central nervous system at the time of the first infusion, thus favoring the clinical manifestation of a pre-existing active lesion.
Human endogenous retrovirus-K18 Env as a risk factor in multiple sclerosis
Authors: Tai AK , O’Reilly EJ , Alroy KA , Simon KC , Munger KL , Huber BT , Ascherio A 
Published: August 2008

Background The human endogenous retrovirus (HERV)-K18 Env is an Epstein-Barr virus (EBV)-associated superantigen. Given the evidence for a role of EBV in the etiology of multiple sclerosis (MS), HERV-K18 Env is a plausible candidate for association with MS. Objective To assess whether variation in HERV-K18 Env is a risk factor for MS. Methods We developed a single nucleotide polymorphism-based genotyping method to determine the distribution of the three alleles of HERV-K18 env. We then conducted a nested case-control study including 207 MS cases and 403 matched controls. Analyses were replicated in an independent series of 909 MS cases and 339 controls. Results Overall, there was a significant association between HERV-K18 env genotype and MS risk (χ2 P = 0.03). As compared with K18.2/K18.2 individuals, risk of MS was three fold higher among K18.3/K18.3 individuals ( P = 0.03). An increase in MS risk among carriers of the K18.3 allele was also observed in the replication study, but did not reach statistical significance. In pooled analyses, K18.3/K18.3 individuals had a significantly increased risk of MS (relative risks [RR] comparing K18.3/K18.3 vs K18.2/K18.2 = 2.7; 95% confidence interval: 1.1–6.4). Conclusion Variation in EBV-associated superantigen HERV-K18 Env could influence the genetic susceptibility to MS.
Frequency and risk factors of mitoxantrone-induced amenorrhea in multiple sclerosis: the FEMIMS study
Authors: Cocco E , Sardu C , Gallo P , Capra R , Amato MP , Trojano M , Uccelli A , Marrosu MG ,   the FEMIMS group*
Published: August 2008

Background Improved prognosis in women with multiple sclerosis (MS) undergoing immunosuppressive treatment with mitoxantrone (MITO) has led to an increased interest in the effect of such treatments on fertility. FErtility and Mitoxantrone In MS (FEMIMS) is a collaborative retrospective study aimed at evaluating the impact of MITO treatment on fertility in women with MS. Methods Occurrence of chemotherapy-induced amenorrhea (CIA) was evaluated in 189 women with MS treated with MITO before the age of 45. An “ad hoc” questionnaire, paying particular attention to onset of CIA either during or post-MITO treatment, was administered to each patient. The probability of CIA was calculated using a multivariate logistic regression analysis taking into account age at exposure, cumulative dose, and use of estroprogestinic (EP) drugs during treatment. Results Forty-eight (26%) patients presented CIA following MITO. The probability of CIA was increased by 2%/mg/m2 of cumulative dose and by 18% for each year of age, whereas it was reduced by administration of EP during treatment. Conclusions MITO treatment may affect reproductive capacity in women with MS. Patients of childbearing age should be properly counseled before MITO treatment and EP therapy should be administered to reduce the risk of CIA.
Use of health services in people with multiple sclerosis with and without fatigue
Authors: Johansson S , Ytterberg C , Gottberg K , Widén Holmqvist L , von Koch L 
Published: August 2008

Objective To explore and compare the use of health services in people with multiple sclerosis (MS) with and without fatigue. Methods Over a period of 30 months, the use of health services in 48 MS outpatients with persistent fatigue and 36 without fatigue was studied. Data were collected from a computerized register and by interviews, and analyzed with regard to disease severity categorized as mild or moderate/severe MS. Results Fatigued people with mild MS used more hospital outpatient care and primary care including rehabilitation, and a higher proportion had transportation service, compared with non-fatigued people with mild MS. In moderate/severe MS, the differences were that non-fatigued people used more occupational therapy in primary care and a higher proportion had salaried service. Regardless of MS severity, informal care was more common among fatigued people. Conclusions Overall, fatigued people with mild MS have more contacts with outpatient health care compared with non-fatigued people. There are few such differences in people with moderate/severe MS. The reasons for the differences in use between fatigued and non-fatigued people are not understood and need further exploration. Fatigued people more often receive informal care, thus support to caregivers are of particular importance if fatigue is present.
Higher levels of 25-hydroxyvitamin D are associated with a lower incidence of multiple sclerosis only in women
Authors: Kragt JJ , van Amerongen BM , Killestein J , Dijkstra CD , Uitdehaag BMJ , Polman CH , Lips P 
Published: August 2008

Introduction Multiple sclerosis (MS) is a chronic inflammatory disease with an as yet not fully understood etiological background. The geographical distribution of MS is striking with a prevalence that increases with latitude. For this reason, vitamin D deficiency is considered a possible pathogenic co-factor in MS. Materials and methods To study the role of the vitamin D metabolism in MS, blood samples were taken twice (summer and winter) from 103 patients with MS and 110 healthy controls. Serum concentrations of 25-hydroxyvitamin D (25(OH) D) and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured, and detailed information on disease characteristics and environmental factors that might influence the vitamin D metabolite levels was collected. Results Mean serum 25(OH)D and 1,25(OH)2D concentrations were significantly higher in summer compared to winter in both patients and controls. Using logistic regression methods, we found that in women for every 10 nmol/L increase of serum 25(OH)D level the odds of MS was reduced by 19% (odds ratio 0.81; 95% confidence interval: 0.69–0.95), suggesting a “protective” effect of higher 25(OH)D serum levels. In addition, also restricted to women, a negative correlation was found between Expanded Disability Status Scale and 25(OH)D levels ( r = −0.29, P = 0.020). Conclusions Our data suggest that higher circulating levels of 25(OH)D are associated with a lower incidence of MS and MS-related disability in women. This may imply clues to the pathogenesis of the sex difference in risk and to the nature of the environmental factors involved in MS.
Angiotensin II receptor blockade and type 2 diabetic nephropathy
Authors: Bilous Rudy W 
Published: August 2008

ACE inhibitors have been shown to reduce albuminuria and slow the progression of nephropathy in type 1 diabetes. There are fewer data in type 2 patients. Three large studies: IRbesartan in patients with type 2 diabetes and MicroAlbuminuria Study (IRMA2), Irbesartan Diabetic Nephropathy Trial (IDNT) and Reduction in End points in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL), of the angiotensin II receptor blockers (ARBs) irbesartan and losartan in microalbuminuric (IRMA2) and nephropathic (IDNT and RENAAL) patients have recently been published. They compared ARBs to conventional treatment, and one used amlodipine as a comparator (IDNT). IRMA2 showed that irbesartan reduced albuminuria in a dose-dependent fashion, achieving a magnitude of response similar to that seen in type 1 diabetic patients. The adjusted hazard ratio for progressing to nephropathy was 0.32 for patients treated with irbesartan 300 mg. IDNT and RENAAL showed that irbesartan 300 mg or losartan 100 mg reduced by 16—19% the numbers of patients reaching a combined end point of doubling of baseline serum creatinine, end-stage renal failure, or all-cause mortality. This effect was not seen in amlodipine treated patients, implying a specific benefit of ARBs. ARBs should be considered as first line therapy in both early and established type 2 diabetic nephropathy.