bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hurricane formation in diabatic Ekman turbulence
Authors: Schecter David A. , Dunkerton Timothy J. 
Published: April 2009

AbstractThis article investigates the emergence of hurricanes from chaotic swirling motions in a three‐layer model of the tropical troposphere that includes basic parametrizations of cumulus convection and air‐‐sea interaction. The chaotic flow is referred to as diabatic Ekman turbulence (DET), in order to emphasize that cumulus convection and Ekman pumping are critical to its behaviour. The time required for hurricane formation in DET is examined over a broad range of sea‐surface temperatures, tropical latitudes and surface exchange coefficients for moist entropy and momentum. The mean trends are sensible, but for a given set of parameters, the genesis time can vary significantly with subtle changes to the initial turbulence. Moreover, hurricanes do not always form. In the event that a tropical depression develops into a hurricane, the process is highly asymmetric. Intensification involves a shear‐flow instability, the production of mesovortices and contraction of the basic circulation. Despite the complex evolution, the intensification rate is largely consistent with the expectations of a quasi‐linear stability analysis. Properties of mature hurricanes and the nature of their fluctuations are discussed in the context of the model. Copyright © 2009 Royal Meteorological Society
The impact of moist processes on the African easterly jet–African easterly wave system
Authors: Cornforth R. J. , Hoskins B. J. , Thorncroft C. D. 
Published: April 2009

AbstractThe African Easterly Jet–Easterly Wave (AEJ–AEW) system was explored in an idealised model. Prescribed zonally symmetric surface temperature and moisture profiles determine the AEJ which becomes established through meridional contrasts in dry and moist convection.As in previous studies, a realistic AEJ developed with only dry convection. Including moist processes, increased its development rate, but reduced its speed and meridional extent. AEWs grew through barotropic–baroclinic conversions. Negative meridional potential vorticity (PV) gradients arose in the zonally symmetric state through the intrusion of the low‐PV Saharan boundary layer. Since moist processes strengthened this significantly through diabatically generated PV in the Intertropical Convergence Zone, moist AEWs were three times stronger. Larger barotropic conversions and faster AEJ development increased the moist wave growth‐rate. Jet‐level and northerly low‐level amplitudes grew, but in the moist case the low‐level amplitudes weakened as the AEW interacted with convection, consistent with their absence from observations during the peak monsoon. Striking dependencies between the AEJ, AEW and rainfall existed. Two time‐scales governed their evolution, depending on the transfer coefficients: (1) the AEJ's replenishment rate influenced by heat fluxes, and (2) the wave growth‐rate, by damping, and the slower jet development rate.Moist AEWs were characterized by intermittent growth/decay, with growth preceded by increased mean rainfall and later, weakening AEJs. These dependencies established an internal 8–10‐day variability, consistent with intra‐seasonal observations of 9‐day rainy sequences. This internal variability offers an alternative explanation to the previously proposed external forcing and a new view of the moist AEW life cycle. Copyright © 2009 Royal Meteorological Society
Measurements of aerosol properties from aircraft, satellite and ground‐based remote sensing: a case‐study from the Dust and Biomass‐burning Experiment (DABEX)
Authors: Johnson B. T. , Christopher S. , Haywood J. M. , Osborne S. R. , McFarlane S. , Hsu C. , Salustro C. , Kahn R. 
Published: April 2009

AbstractThis paper presents aircraft measurements of aerosol optical properties and radiative effects from the Dust and Biomass‐burning Experiment (DABEX) over West Africa. On 19 January 2006 cloud‐free skies and high aerosol loading provided ideal conditions for an intercomparison of aircraft, satellite and ground‐based remote sensing instruments. Aerosol size distributions, optical properties, aerosol optical depth (AOD) and downwelling solar radiation were measured by the UK FAAM aircraft in the region of Niamey, Niger. The aircraft in situ measurements showed a mixture of dust and biomass‐burning aerosols and indicated an AOD of 0.79 (at 550 nm) that compared well against AODs from the Banizoumbou Aerosol Robotic Network (AERONET) site (0.74) and a Microtops sunphotometer (0.72). AERONET size distributions showed a good degree of similarity with the aircraft in situ measurements. AERONET single‐scattering albedos were also in fairly close agreement with the aircraft, having values of 0.85 and 0.87, respectively (at 550 nm). Measurements of downwelling solar radiation from the aircraft compared well with measurements from the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) at Niamey. Radiative transfer modelling suggested a 130–160 W m−2 instantaneous reduction of downwelling solar radiation by the aerosol column (15–18% of the total flux). Measurements of downwelling solar radiation compared reasonably well against radiative transfer modelling based on the aircraft in situ data. Satellite retrievals of AOD from MISR and MODIS Deep Blue were within 0.05 of the ground‐based sunphotometers measurements although there were discrepancies in optical properties retrieved by MISR, as compared to AERONET and the aircraft. Copyright © Royal Meteorological Society, Crown Copyright 2009
Infrasound generation by tornadic supercell storms
Authors: Akhalkatsi M. , Gogoberidze G. 
Published: April 2009

AbstractAcoustic wave generation by turbulence in a stratified, moist atmosphere is studied. It is shown that, in saturated moist air turbulence, in addition to the Lighthill's quadrupole and dipole sources of sound (related to stratification and temperature fluctuations), there exist monopole sources related to heat and mass production during the condensation of moisture. We determine the acoustic power of these monopole sources and show that this radiation is dominant for typical parameters of strong convective storms. The results are in good qualitative agreement with the main observed characteristics of infrasound radiation by strong convective storms, e.g. total acoustic power and characteristic frequency. Copyright © 2009 Royal Meteorological Society
Improving the numerical prediction of a cyclone in the Mediterranean by local potential vorticity modifications
Authors: Argence Sébastien , Lambert Dominique , Richard Evelyne , Pierre Chaboureau Jean , Philippe Arbogast Jean , Maynard Karine 
Published: April 2009

AbstractThis study explores the benefit that can be drawn from incorporating local potential vorticity (PV) modifications into a numerical forecast. The case under study is the severe cyclogenesis that occurred in the Western Mediterranean from 9 to 12 November 2001. This case was shown to be extremely sensitive to the upper‐level flow, which governed to a great extent the deepening of the depression and the location and intensity of its associated precipitation. Corrections of PV were guided by METEOSAT‐7 water vapour observations and restricted to the upper troposphere, mainly altering the topography of the dynamical tropopause. Using both the French operational global model ARPEGE and the non‐hydrostatic mesoscale model Meso‐NH, it is shown that carefully designed PV corrections lead to a substantial improvement in the simulation of the storm, both in terms of surface pressure, cloud cover and precipitation forecasts. Furthermore, the impact of the modifications is shown to be a maximum when they are introduced at the time corresponding to the incipient stage of cyclogenesis. Copyright © 2009 Royal Meteorological Society
Factors influencing cloud area at the capping inversion for shallow cumulus clouds
Authors: Lock A. P. 
Published: April 2009

AbstractLarge‐eddy simulations of marine cumulus clouds are performed. Aspects of the simulations are varied in order to identify those parameters that play a role in determining when the cumulus clouds spread out under the capping inversion into stratocumulus. These include the strength of the surface fluxes, which also affects the strength of the cumulus mass transport, the strength of the capping inversion, the moisture content of the free atmosphere, the strength of cloud‐top radiative cooling and whether there is significant precipitation or sedimentation of cloud drops. Tests are also performed to evaluate sensitivity to the model resolution.As in previous studies, having sufficient resolution at the capping inversion is found to be important for robust simulation of any stratiform cloud that forms there. In addition, the cloud cover is found to be sensitive to many of the physical processes investigated. In the end, though, a clear and robust dependence emerges on the cloud‐top entrainment instability parameter, κ. For large κ, a typical (small) shallow cumulus cloud cover is seen. For κ below the threshold for buoyancy reversal, the cumulus spreads into a solid sheet of stratocumulus beneath the inversion. Consistent with previous studies, there is no abrupt transition and the cloud cover decreases smoothly as κ increases. The conclusion is reached that varying other parameters in the simulations affects the cloud cover through their impact on the size of the jumps across the inversion and thence κ. The implications for turbulent mixing parametrizations in general circulation models are discussed. © Crown Copyright 2009. Reproduced with the permission of HMSO. Published by John Wiley & Sons, Ltd.
Optimized port placement for in vivo biosensors
Authors: King Brady W. , Reisner Luke A. , Ellis R. Darin , Klein Michael D. , Auner Gregory W. , Pandya Abhilash K. 
Published: April 2009

AbstractBackgroundWe discuss the implementation of an automated port placement system for use with laparoscopic in vivo biosensors. Biosensors have physical limitations that make port placement crucial to proper data collection. The port placement process is prohibitively complex to execute optimally by human estimation.MethodsPort placement algorithms were integrated into an image‐guided surgery system. Variables for optimization of ports include biosensor length, data collection restrictions, obstacles, and regions of interest. The port placement is applied to 3D virtual ‘patients’ created from medical imaging data. An example implementation for a Raman biosensor probe was created.ResultsThe prototype system can correctly find ideal port locations on a virtual patient based on biosensor limitations and regions of interest. Conversely, the system can evaluate and score an individual port selected by a user.ConclusionAs biosensors become incorporated into laparoscopic surgical environments, an automated port placement system would enable their optimized integration. Copyright © 2009 John Wiley & Sons, Ltd.
Involvement of the nucleolus in replication of human viruses
Authors: Greco Anna 
Published: April 2009

AbstractViruses are intracellular pathogens that have to usurp some of the cellular machineries to provide an optimal environment for their own replication. An increasing number of reports reveal that many viruses induce modifications of nuclear substructures including nucleoli, whether they replicate or not in the nucleus of infected cells. Indeed, during infection of cells with various types of human viruses, nucleoli undergo important morphological modifications. A large number of viral components traffic to and from the nucleolus where they interact with different cellular and/or viral factors, numerous host nucleolar proteins are redistributed in other cell compartments or are modified and some cellular proteins are delocalised in the nucleolus of infected cells. Well‐documented studies have established that several of these nucleolar modifications play a role in some steps of the viral cycle, and also in fundamental cellular pathways. The nucleolus itself is the place where several essential steps of the viral cycle take place. In other cases, viruses divert host nucleolar proteins from their known functions in order to exert new unexpected role(s). Copyright © 2009 John Wiley & Sons, Ltd.
Investigations on the leaf surface ultrastructure in grapevine (Vitis vinifera L.) by scanning microscopy
Authors: Bensalem‐fnayou A. , Jellouli N. , Bouamama B. , Mliki A. , Ghorbel A. 
Published: April 2009

AbstractSeveral Scanning microscopy techniques were used to investigate the leaf surface ultrastructure in the local “Razegui” grapevine cultivar (Vitis vinifera L.). Conventional scanning electron microscopy performed on glutaraldehyde‐fixed samples allowed observation of well‐preserved epidermal cells with an overlaying waxy layer. At a high magnification, the waxy layer exhibited crystalline projections in the form of horizontal and vertical platelets. Also, to avoid eventual ultrastructural alterations inherent in the use of solvents during sample preparation, fresh leaf blade samples were directly observed by environmental scanning electron microscopy. A classical image of convex living epidermal cells was observed. At 2400× magnification, epicuticular waxes exhibited a granular structure. However, high‐magnification images were not obtained with this device. The atomic force microscopy (AFM) performed on fresh leaf blade samples allowed observation of a textured surface and heterogeneous profiles attributed to epicuticular wax deposits. AFM topography images confirmed further, the presence of irregular crystalloid wax projections as multishaped platelets on the adaxial surface of grapevine leaf. SCANNING 31: 127–131, 2009. © 2009 Wiley Periodicals, Inc.
Hierarchical additive modeling of nonlinear association with spatial correlations—An application to relate alcohol outlet density and neighborhood assault rates
Authors: Yu Qingzhao , Li Bin , Scribner Richard Allen 
Published: April 2009

AbstractPrevious studies have suggested a link between alcohol outlets and assaults. In this paper, we explore the effects of alcohol availability on assaults at the census tract level over time. In addition, we use a natural experiment to check whether a sudden loss of alcohol outlets is associated with deeper decreasing in assault violence. Several features of the data raise statistical challenges: (1) the association between covariates (for example, the alcohol outlet density of each census tract) and the assault rates may be complex and therefore cannot be described using a linear model without covariates transformation, (2) the covariates may be highly correlated with each other, (3) there are a number of observations that have missing inputs, and (4) there is spatial association in assault rates at the census tract level. We propose a hierarchical additive model, where the nonlinear correlations and the complex interaction effects are modeled using the multiple additive regression trees and the residual spatial association in the assault rates that cannot be explained in the model are smoothed using a conditional autoregressive (CAR) method. We develop a two‐stage algorithm that connects the nonparametric trees with CAR to look for important covariates associated with the assault rates, while taking into account the spatial association of assault rates in adjacent census tracts. The proposed method is applied to the Los Angeles assault data (1990–1999). To assess the efficiency of the method, the results are compared with those obtained from a hierarchical linear model. Copyright © 2009 John Wiley & Sons, Ltd.
Accurate estimates without local data?
Authors: Menzies Tim , Williams Steve , Elrawas Oussama , Baker Daniel , Boehm Barry , Hihn Jairus , Lum Karen , Madachy Ray 
Published: April 2009

AbstractModels of software projects input project details and output predictions via their internal tunings. The output predictions, therefore, are affected by variance in the project details P and variance in the internal tunings T. Local data is often used to constrain the internal tunings (reducing T).While constraining internal tunings with local data is always the preferred option, there exist some models for which constraining tuning is optional. We show empirically that, for the USC COCOMO family of models, the effects of P dominate the effects of T i.e. the output variance of these models can be controlled without using local data to constrain the tuning variance (in ten case studies, we show that the estimates generated by only constraining P are very similar to those produced by constraining T with historical data).We conclude that, if possible, models should be designed such that the effects of the project options dominate the effects of the tuning options. Such models can be used for the purposes of decision making without elaborate, tedious, and time‐consuming data collection from the local domain. Copyright © 2009 John Wiley & Sons, Ltd.
Fetal intraperitoneal transfusion for iatrogenic twin anemia–polycythemia sequence after laser therapy
Authors: Herway C. , Johnson A. , Moise K. , Moise K. J. 
Published: April 2009

AbstractTwin anemia–polycythemia sequence (TAPS) is a rare variant of twin–twin transfusion syndrome (TTTS) without the characteristic twin oligohydramnios–polyhydramnios sequence and cardiovascular milieu attributed to renin–angiotensin system mediators. It can occur spontaneously or iatrogenically after fetoscopic laser surgery. We report the case of a woman, gravida 2 para 1, with a monochorionic diamniotic pregnancy who developed Quintero Stage III TTTS. She underwent laser photocoagulation of identifiable anastomotic vessels and subsequently developed suspected TAPS 2 weeks later. The pregnancy was successfully treated with serial intrauterine intraperitoneal transfusions (IUT‐PTs) of red blood cells. Although TAPS is a rare condition, serial middle cerebral artery peak systolic velocity measurements are warranted as follow‐up in patients who have undergone fetoscopic laser surgery for TTTS. IUT‐PTs may be superior to intravascular intrauterine transfusions in the treatment of this condition. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal dilated cardiomyopathy caused by persistent junctional reciprocating tachycardia
Authors: Cornette J. , Ten Harkel A. D. J. , Steegers E. A. P 
Published: April 2009

AbstractUltrasound examination of a fetus at 32 weeks' gestation revealed dilated cardiomyopathy and a heart rate of 170 beats per minute. Prenatally, this mild tachycardia was not primarily suspected to be the cause of the myocardial changes. Postnatal electrocardiography revealed a persistent junctional reciprocating tachycardia (PJRT) and the diagnosis of tachycardia‐induced cardiomyopathy (TICM) became apparent. After conversion to a sinus rhythm under digoxin and amiodarone, the cardiac changes regressed. PJRT is a rare form of supraventricular tachycardia. The prenatal findings in the condition have previously been described retrospectively, but it can only be diagnosed postnatally by its characteristic electrocardiographic properties. This case indicates that TICM can occur at lower heart rates than previously assumed. Even severe prenatal cardiomyopathy may be reversible once sinus rhythm has been restored. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Role of uterine artery Doppler in interpreting low PAPP‐A values in first‐trimester screening for Down syndrome in pregnancies at high risk of impaired placentation
Authors: Herraiz I. , López‐Jiménez E. A. , García‐Burguillo A. , Nieto O. , Villar O. P. , Escribano D. , Galindo A. 
Published: April 2009

AbstractObjectivesLow maternal serum levels of pregnancy‐associated plasma protein‐A (PAPP‐A) are associated with both increased risk of aneuploidies and impaired trophoblastic invasion, while high uterine artery (UtA) resistance is associated with impaired trophoblastic invasion but not with an increased risk of aneuploidies. The aim of this study was to determine whether high UtA resistance plays a role in explaining low PAPP‐A levels in the absence of aneuploidies.MethodsThis was a prospective study of 116 singleton pregnancies at high risk for impaired placentation (having at least one major risk factor: prior history of pre‐eclampsia, pregestational diabetes mellitus, chronic hypertension, chronic kidney disease, body mass index >30, autoimmune disorder, thrombophilia or recurrent pregnancy loss), booked for routine assessment of risk for aneuploidies by means of the first‐trimester combined screening test (nuchal translucency thickness (NT) + PAPP‐A + beta‐human chorionic gonadotropin (β‐hCG)). Measurement of NT and the mean UtA pulsatility index (PI) were carried out at the 11 to 13 + 6‐week scan. All values were calculated in multiples of the median (MoM) adjusted for gestational age. A cut‐off risk of 1/270 at time of sampling was adopted to differentiate high‐ from low‐risk groups for trisomy 21.ResultsThere were 108 patients deemed to be at low risk for trisomy 21 and eight at high risk. None had chromosomal defects, giving a false‐positive rate for trisomy 21 of 6.9%. The greatest differences between patients at low risk and those at high risk for trisomy 21 were found in their PAPP‐A (0.98 vs. 0.38 MoM, P < 0.01) and β‐hCG (1.09 vs. 1.77 MoM, P = 0.04) values. Greater NT thickness (1.02 vs. 0.90 MoM) and higher mean UtA‐PI (1.05 vs. 0.96 MoM) were recorded in the high‐risk group, although the differences did not reach statistical significance (P = 0.19 and 0.40, respectively). After log‐transformation there were no significant correlations between mean UtA‐PI and NT and between mean UtA‐PI and β‐hCG. There was a significant negative linear correlation between mean UtA‐PI and PAPP‐A (r = −0.331; P < 0.01). After adjusting the PAPP‐A values by UtA‐PI, the false‐positive rate for trisomy 21 decreased to 2.6%.ConclusionMean UtA‐PI at the 11 to 13 + 6‐week scan may be an effect‐modifier variable for PAPP‐A that should be taken into account in the first‐trimester combined screening for aneuploidies, at least in pregnancies at high risk for impaired placentation. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Can quantitative three‐dimensional power Doppler angiography be used to predict ovarian hyperstimulation syndrome?
Authors: Jayaprakasan K. , Jayaprakasan R. , Al‐Hasie H. A. , Clewes J. S. , Campbell B. K. , Johnson I. R. , Raine‐Fenning N. J. 
Published: April 2009

AbstractObjectiveTo test the hypothesis that ovarian vascularity is increased in women developing ovarian hyperstimulation syndrome (OHSS) and to assess its value as a predictor of OHSS during in‐vitro fertilization (IVF).Methods118 subjects undergoing their first cycle of IVF had a three‐dimensional (3D) transvaginal ultrasound scan in the early follicular phase of the menstrual cycle preceding IVF treatment. 18 of them developed moderate or severe OHSS and 100 subjects had normal ovarian response. Antral follicle count, ovarian volume, and ovarian vascularity (vascularization index (VI), flow index (FI) and vascularization flow index (VFI)) were compared between OHSS and control groups. Multiple regression analysis was used to assess the predictive value of these variables against age, body mass index and basal follicle‐stimulating hormone level for the development of OHSS.ResultsThe ovarian blood flow indices VI (11.1 ± 11.6 vs. 8.6 ± 7.3%; P = 0.23), FI (38.0 ± 4.8 vs. 38.0 ± 5.5; P = 0.95) and VFI (4.2 ± 3.3 vs. 3.5 ± 3.1; P = 0.40) were similar in the OHSS group and the normal responders. While antral follicle count was significantly higher in women developing OHSS (33.0 ± 15.1) than in the control group (19.2 ± 9.9, P < 0.001), ovarian volume did not differ between the two groups (10.6 ± 3.8 vs. 8.9 ± 4.8 cm3, respectively, P = 0.11). On multiple regression analysis, antral follicle count was the only significant predictor of OHSS (P < 0.01).ConclusionsWomen developing OHSS during IVF do not demonstrate an increased ovarian blood flow as measured by 3D ultrasound but do have a significantly higher antral follicle count, which is the only significant predictor of OHSS. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.