bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-Term Variability of Daily North Atlantic–European Pressure Patterns since 1850 Classified by Simulated Annealing Clustering
Authors: Philipp A. , Della-Marta P. M. , Jacobeit J. , Fereday D. R. , Jones P. D. , Moberg A. , Wanner H. 
Published: August 2007

AbstractReconstructed daily mean sea level pressure patterns of the North Atlantic–European region are classified for the period 1850 to 2003 to explore long-term changes of the atmospheric circulation and its impact on long-term temperature variability in the central European region. Commonly used k-means clustering algorithms resulted in classifications of low quality because of methodological deficiencies leading to local optima by chance for complex datasets. In contrast, a newly implemented clustering scheme combining the concepts of simulated annealing and diversified randomization (SANDRA) is able to reduce substantially the influence of chance in the cluster assignment, leading to partitions that are noticeably nearer to the global optimum and more stable. The differences between conventional cluster analysis and the SANDRA scheme are significant for subsequent analyses of single clusters—in particular, for trend analysis. Conventional indices used to determine the appropriate number of clusters failed to provide clear guidance, indicating that no distinct separation between clusters of circulation types exists in the dataset. Therefore, the number of clusters is determined by an external indicator, the so-called dominance criteria for t-mode principal component analysis. Nevertheless, the resulting partitions are stable for certain numbers of clusters and provide meaningful and reproducible clusters. The resulting types of pressure patterns reveal pronounced long-term variability and various significant trends of the time series of seasonal cluster frequency. Tentative estimations of central European temperature changes based solely on seasonal cluster frequencies can explain between 33.9% (summer) and 59.0% (winter) of temperature variance on the seasonal time scale. However, the signs of long-term changes in temperature are correctly reproduced even on multidecadal–centennial time scales. Moreover, linear warming trends are reproduced, implying from one-third up to one-half of the observed temperature increase between 1851/52 and 2003 (except for summer, but with significant trends for spring and autumn), indicating that changes in daily circulation patterns contribute to the observed overall long-term warming in the central European region.
The Effect of Orbital Forcing on the Mean Climate and Variability of the Tropical Pacific
Authors: Timmermann A. , Lorenz S. J. , An S-I. , Clement A. , Xie S-P. 
Published: August 2007

Abstract
Using a coupled general circulation model, the responses of the climate mean state, the annual cycle, and the El Niño–Southern Oscillation (ENSO) phenomenon to orbital changes are studied. The authors analyze a 1650-yr-long simulation with accelerated orbital forcing, representing the period from 142 000 yr b.p. (before present) to 22 900 yr a.p. (after present). The model simulation does not include the time-varying boundary conditions due to ice sheet and greenhouse gas forcing.
Owing to the mean seasonal cycle of cloudiness in the off-equatorial regions, an annual mean precessional signal of temperatures is generated outside the equator. The resulting meridional SST gradient in the eastern equatorial Pacific modulates the annual mean meridional asymmetry and hence the strength of the equatorial annual cycle. In turn, changes of the equatorial annual cycle trigger abrupt changes of ENSO variability via frequency entrainment, resulting in an anticorrelation between annual cycle strength and ENSO amplitude on precessional time scales.
Improved Skill of Northern Hemisphere Winter Surface Temperature Predictions Based on Land–Atmosphere Fall Anomalies
Authors: Cohen Judah , Fletcher Christopher 
Published: August 2007

AbstractA statistical forecast model, referred to as the snow-cast (sCast) model, has been developed using observed October mean snow cover and sea level pressure anomalies to predict upcoming winter land surface temperatures for the extratropical Northern Hemisphere. In operational forecasts since 1999, snow cover has been used for seven winters, and sea level pressure anomalies for three winters. Presented are skill scores for these seven real-time forecasts and also for 33 winter hindcasts (1972/73–2004/05). The model demonstrates positive skill over much of the eastern United States and northern Eurasia—regions that have eluded skillful predictions among the existing major seasonal forecast centers. Comparison with three leading dynamical forecast systems shows that the statistical model produces superior skill for the same regions. Despite the increasing complexity of the dynamical models, they continue to derive their forecast skill predominantly from tropical atmosphere–ocean coupling, in particular from ENSO. Therefore, in the Northern Hemisphere extratropics, away from the influence of ENSO, the sCast model is expected to outperform the dynamical models into the foreseeable future.
Relative Roles of Different Components of the Basic State in the Phase Locking of El Niño Mature Phases
Authors: Yan Bangliang , Wu Renguang 
Published: August 2007

AbstractThe mature phases of El Niño events show a strong tendency of locking to the end of the calendar year. The roles of seasonal variations of the basic state and the relative contributions of individual components of the basic state in this phase locking are investigated using the Zebiak–Cane model. It is shown that seasonal variations of the mean state from July to November have a positive contribution and those from December to June have a negative contribution to preexisting warm SST anomalies. Among the basic-state parameters, the sea surface temperature (SST) is a major factor for the locking of the El Niño mature phase through the anomalous advection of the mean SST gradient. This result differs from previous studies that attribute the El Niño phase locking mainly to seasonal changes in the mean wind divergence. The present result indicates the importance of a proper simulation of mean SST and its seasonal evolution for the simulation of El Niño phase locking in coupled models. Further experiments show that the phase locking of the El Niño mature phase cannot be explained by a balance between the warming trend due to downwelling Kelvin waves and the cooling trend due to upwelling Rossby waves.
Influence of Arctic Wetlands on Arctic Atmospheric Circulation
Authors: Gutowski William J. , Wei Helin , Vörösmarty Charles J. , Fekete Balázs M. 
Published: August 2007

Abstract
The Arctic’s land surface has large areas of wetlands that exchange moisture, energy, and momentum with the atmosphere. The authors use a mesoscale, pan-Arctic model simulating the summer of 1986 to examine links between the wetlands and arctic atmospheric dynamics and water cycling. Simulations with and without wetlands are compared to simulations using perturbed initial and lateral boundary conditions to delineate when and where the wetlands influence rises above nonlinear internal variability. The perturbation runs expose the temporal variability of the circulation’s sensitivity to changes in lower boundary conditions. For the wetlands cases examined here, the period of the most significant influence is approximately two weeks, and the wetlands do not introduce new circulation changes but rather appear to reinforce and modify existing circulation responses to perturbations. The largest circulation sensitivity, and thus the largest wetlands influence, occurs in central Siberia. The circulation changes induced by adding the wetlands appear as a propagating, equivalent barotropic wave. The wetlands anomaly circulation spreads alterations of surface fluxes to other locations, which undermines the potential for the wetlands to present a distinctive, spatially fixed forcing to atmospheric circulation. Using the climatology of artic synoptic-storm occurrence to indicate when the arctic circulation is most sensitive to altered forcing, the results suggest that the circulation is susceptible to the direct influence of wetlands for a limited time period extending from spring thaw of wetlands until synoptic-storm occurrence diminishes in midsummer. Sensitivities in arctic circulation uncovered through this work occur during a period of substantial transition from a fundamentally frozen to thawed state, a period of major concern for impacts of greenhouse warming on pan-Arctic climate. Changing arctic climate could alter the behavior revealed here.
Horizontal and Vertical Structures of the Northward-Propagating Intraseasonal Oscillation in the South Asian Monsoon Region Simulated by an Intermediate Model*
Authors: Drbohlav Hae-Kyung Lee , Wang Bin 
Published: August 2007

Abstract
The structures and mechanism of the northward-propagating boreal summer intraseasonal oscillation (BSISO) in the southern Asian monsoon region are simulated and investigated in a three-dimensional intermediate model (3D model). The horizontal structure of the intraseasonal variability in the 3D model depicts the Kelvin–Rossby wave–type disturbance, which may or may not produce the northward-propagating disturbance in the Indian Ocean, depending on the seasonal-mean background winds.
Two experiments are conducted in order to identify what characteristic of seasonal-mean background can induce the northwestward-tilted band in the Kelvin–Rossby wave, whose overall eastward movement gives the impression of the northward propagation at a given longitude. When the prescribed boreal summer mean winds are excluded in the first experiment, the phase difference between the barotropic divergence tendency and convection disappears. Consequently, the Rossby wave–type convection forms a zonally elongated band. As a result, the northward propagation of convection at a given longitude disappears. When the easterly vertical shear is introduced in the second experiment, the horizontal and the vertical structures of BSISO become similar to that of the northward-propagating one. The reoccurrence of the northwestward-directed convective band and the phase difference between the barotropic divergence tendency and the convection suggest that the summer mean zonal winds in the boreal Indian summer monsoon region are a critical condition that causes the horizontal and vertical structures of northward-propagating BSISO in the southern Asian monsoon region.
Low-Frequency Variability of the Indian Monsoon–ENSO Relationship and the Tropical Atlantic: The “Weakening” of the 1980s and 1990s
Authors: Kucharski F. , Bracco A. , Yoo J. H. , Molteni F. 
Published: August 2007

Abstract
The Indian monsoon–El Niño–Southern Oscillation (ENSO) relationship, according to which a drier than normal monsoon season precedes peak El Niño conditions, weakened significantly during the last two decades of the twentieth century. In this work an ensemble of integrations of an atmospheric general circulation model (AGCM) coupled to an ocean model in the Indian Basin and forced with observed sea surface temperatures (SSTs) elsewhere is used to investigate the causes of such a weakening.
The observed interdecadal variability of the ENSO–monsoon relationship during the period 1950–99 is realistically simulated by the model and a dominant portion of the variability is associated with changes in the tropical Atlantic SSTs in boreal summer.
In correspondence to ENSO, the tropical Atlantic SSTs display negative anomalies south of the equator in the last quarter of the twentieth century and weakly positive anomalies in the previous period. Those anomalies in turn produce heating anomalies, which excite a Rossby wave response in the Indian Ocean in both the model and the reanalysis data, impacting the time-mean monsoon circulation.
The proposed mechanism of remote response of the Indian rainfall to tropical Atlantic sea surface temperatures is further tested forcing the AGCM coupled to the ocean model in the Indian Basin with climatological SSTs in the Atlantic Ocean and observed anomalies elsewhere. In this second ensemble the ENSO–monsoon relationship is characterized by a stable and strong anticorrelation through the whole second half of the twentieth century.
A Novel Bioabsorbable Conduit Augments Healing of Avascular Meniscal Tears in a Dog Model
Authors: Cook James L. , Fox Derek B. 
Published: August 2007

Background Avascular meniscal tears are a common and costly problem for which current treatment options are limited. Hypothesis A bioabsorbable conduit will allow for vascular tissue ingrowth that is associated with histologic and biomechanical evidence for avascular meniscal tear healing superior to that associated with meniscal trephining in dogs. Study Design Controlled laboratory study. Methods Twenty-five dogs underwent medial arthrotomy with creation of anterior and posterior tears in the medial menisci (N = 50 tears). The dogs were assigned treatments for their menisci: conduit (n = 29 tears) or trephine (n = 21 tears). Dogs were assessed for lameness by subjective scoring after surgery and sacrificed at 6, 12, or 24 weeks and assessed for articular cartilage damage, gross and histologic appearance of the operated menisci, and maximal load-to-failure values using tensile testing of meniscal tears. Tears were considered to demonstrate biomechanical integrity when histologic partial to complete healing was noted in conjunction with a measured load to failure that was significantly greater than controls. Results Based on histologic assessment, the conduit was associated with complete (n = 4) or partial (n = 5) healing in all avascular defects at 12 and 24 weeks after surgery in this study. No healing was seen in defects treated by trephination and repair. No lameness associated with surgery or meniscal treatment was noted after 4 weeks. No articular cartilage damage was noted in any joint. At both 12 and 24 weeks, mean load to failure for normal menisci (43.2 N and 28.6 N, respectively) was significantly (P < .017) higher than conduit-treated (22.3 N and 16.0 N, respectively) and trephine-treated (0.6 N and 2.1 N, respectively) menisci, and load to failure for conduit-treated menisci was significantly (P ≤ .05) higher than trephine-treated menisci. Biomechanical integrity was noted in 10 of 14 conduit-treated menisci. Conclusion Conduit treatment resulted in functional healing with bridging tissue and biomechanical integrity in 71% of avascular meniscal defects for up to 6 months after surgery. No functional healing was noted in avascular meniscal tears treated by trephination and suture repair. Clinical Relevance Clinical studies using the conduit in humans may be appropriate to determine the safety and efficacy of the device for cases of avascular and poorly vascularized meniscal tears, where the device can be successfully implanted from tear to meniscal rim, the tears can be surgically repaired, and patient compliance can be ensured.
Double-Bundle Anterior Cruciate Ligament Reconstruction
Authors: Ferretti Andrea , Monaco Edoardo , Labianca Luca , Conteduca Fabio , De Carli Angelo 
Published: August 2007

Background The biomechanical function of single-bundle anterior cruciate ligament reconstruction, in cadaveric studies, is successful in limiting anterior tibial translation in response to an anterior tibial load but seems to be insufficient to control a combined rotator load of internal and valgus torque. Anatomical double-bundle anterior cruciate ligament reconstruction might produce a better biomechanical outcome. Hypothesis The addition of the posterolateral bundle to the anteromedial bundle, in an in vivo double-bundle computer-assisted anterior cruciate ligament reconstruction, is able to reduce internal rotation of the tibia at 30° of knee flexion, compared with a standard single-bundle reconstruction. Study Design Controlled laboratory study. Methods Twenty consecutive anterior cruciate ligament reconstructions were performed in male patients in April and May 2006 with double-bundle gracilis and semitendinosus tendon grafts using the 2.0 OrthoPilot navigation system. Group A (10 patients) underwent standard single-bundle anterior cruciate ligament reconstruction with doubled gracilis and semitendinosus tendon graft; group B (10 patients) underwent double-bundle reconstruction with doubled gracilis and semitendinosus tendon graft. Anteroposterior displacement and internal and external rotation at 30° of knee flexion were evaluated before and after reconstruction, using manual maximum force. Results Both techniques significantly reduced anteroposterior displacement and internal and external rotation of the tibia with respect to preoperative anterior cruciate ligament–deficient condition ( P < .05). Comparing groups, no differences in anteroposterior tibial displacement and internal and external rotation of the tibia were found (anteroposterior, 3.7 mm and 5.2 mm; internal rotation, 16.3° and 16.6°; external rotation, 15.7° and 15.1°, respectively) in group A and B ( P = .06, .90, and .72, respectively). Conclusion The hypothesis that addition of the posterolateral bundle to the anteromedial bundle is able to reduce internal rotation of the tibia at 30° of knee flexion is not confirmed. Clinical Relevance The effective role of the anatomical double-bundle procedure in better restoring knee kinematics should be questioned in an in vivo model.
Increased TSLP availability restores T- and B-cell compartments in adult IL-7–deficient mice
Authors: Chappaz Stephane , Flueck Lukas , Farr Andrew G. , Rolink Antonius G. , Finke Daniela 
Published: August 2007

AbstractInterleukin 7 (IL-7) plays a crucial role in adult lymphopoiesis, while in fetal life its effect can be partially compensated by TSLP. Whether adult hematopoietic progenitor cells are unresponsive to TSLP or whether TSLP is less available in adult microenvironments is still a matter of debate. Here, we show that increased TSLP availability through transgene (Tg) expression fully restored lymphopoiesis in IL-7–deficient mice: it rescued B-cell development, increased thymic and splenic cellularities, and restored double-negative (DN) thymocytes, αβ and γδ T-cell generation, and all peripheral lymphoid compartments. Analysis of bone marrow chimeras demonstrated that hematopoietic progenitor cells from adult wild-type mice efficiently differentiated toward B- and T-cell lineages in lethally irradiated IL-7 deficient mice provided TSLP Tg was expressed in these mice. In vitro, TSLP promoted the differentiation of uncommitted adult bone marrow progenitors toward B and T lineages and the further differentiation of DN1 and DN2 thymocytes. Altogether, our results show that adult hematopoietic cells are TSLP responsive and that TSLP can sustain long-term adult lymphopoiesis.
Establishment of transplantable porcine tumor cell lines derived from MHC- inbred miniature swine
Authors: Cho Patricia S. , Lo Diana P. , Wikiel Krzysztof J. , Rowland Haley C. , Coburn Rebecca C. , McMorrow Isabel M. , Goodrich Jennifer G. , Arn J. Scott , Billiter Robert A. , Houser Stuart L. , Shimizu Akira , Yang Yong-Guang , Sachs David H. , Huang Christene A. 
Published: August 2007

AbstractThe lack of transplantable tumors has limited assessment of graft-versus-tumor effects following hematopoietic cell transplantation in clinically relevant large-animal models. We describe the derivation and characterization of porcine tumor cell lines with initial efforts of tumor transplantation using immunocompromised mice and highly inbred sublines of Massachusetts General Hospital major histocompatibility complex (MHC)–inbred miniature swine. Autopsies were performed routinely on swine that died unexpectedly or had suspicion of malignancy based on clinical symptoms or peripheral blood analysis. Tissue samples were obtained for pathology, phenotyped by flow cytometry, and placed in culture. Based on growth, lines were selected for passage into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice and miniature swine. Porcine tumor recipients were preconditioned with total body irradiation from 0 to 500 cGy or with a 30-day course of oral cyclosporine. We identified 19 cases of hematologic tumors. Nine distinct tumor cell lines were established from 8 of these cases, including 3 derived from highly inbred sublines. In vivo tumor growth and serial transfer were observed in immunocompromised mice for one tumor cell line and in miniature swine for 1 of 2 tumor cell lines expanded for this purpose. These results suggest the possibility of developing a transplantable tumor model in this large-animal system.
Effect of the complement inhibitor eculizumab on thromboembolism in patients with paroxysmal nocturnal hemoglobinuria
Authors: Hillmen Peter , Muus Petra , Dührsen Ulrich , Risitano Antonio M. , Schubert Jörg , Luzzatto Lucio , Schrezenmeier Hubert , Szer Jeffrey , Brodsky Robert A. , Hill Anita , Socié Gerard , Bessler Monica , Rollins Scott A. , Bell Leonard , Rother Russell P. , Young Neal S. 
Published: August 2007

AbstractHemolysis and hemoglobinemia contribute to serious clinical sequelae in hemolytic disorders. In paroxysmal nocturnal hemoglobinuria (PNH) patients, hemolysis can contribute to thromboembolism (TE), the most feared complication in PNH, and the leading cause of disease-related deaths. We evaluated whether long-term treatment with the complement inhibitor eculizumab reduces the rate of TE in patients with PNH. Clinical trial participants included all patients in the 3 eculizumab PNH clinical studies, which recruited patients between 2002 and 2005 (n = 195); patients from these studies continued treatment in the current multinational open-label extension study. Thromboembolism rate with eculizumab treatment was compared with the pretreatment rate in the same patients. The TE event rate with eculizumab treatment was 1.07 events/100 patient-years compared with 7.37 events/100 patient-years (P < .001) prior to eculizumab treatment (relative reduction, 85%; absolute reduction, 6.3 TE events/100 patient-years). With equalization of the duration of exposure before and during treatment for each patient, TE events were reduced from 39 events before eculizumab to 3 events during eculizumab (P < .001). The TE event rate in antithrombotic-treated patients (n = 103) was reduced from 10.61 to 0.62 events/100 patient-years with eculizumab treatment (P < .001). These results show that eculizumab treatment reduces the risk of clinical thromboembolism in patients with PNH. This study is registered at http://clinicaltrials.gov (study ID no. NCT00122317).