bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two‐echelon distribution systems with random demands and storage constraints
Authors: Federgruen Awi , Guetta C. Daniel , Iyengar Garud 
Published: December 2018

We consider a general two‐echelon distribution system consisting of a depot and multiple sales outlets, henceforth referred to as retailers, which face random demands for a given item. The replenishment process consists of two stages: the depot procures the item from an outside supplier, while the retailers' inventories are replenished by shipments from the depot. Both of the replenishment stages are associated with a given facility‐specific leadtime. The depot as well as the retailers faces a limited inventory capacity. Inventories are reviewed and orders are placed on a periodic basis. When a retailer runs out of stock, unmet demand is backlogged.We propose a new approach to the above class of dynamic programming models based on Lagrangian relaxation. Every choice of the vector of Lagrange multipliers generates a lower bound via the solution of a single dynamic program (DP) with a one‐dimensional state‐space. The best such bound is obtained by maximizing over the vector of multipliers. The strategy that is optimal for this (maximal) lower bound DP employs an (s, S) ordering policy (generally, with time‐dependent policy parameters). To arrive at an upper bound and an implementable heuristic, this (s, S) policy is paired with one of several possible allocation policies that allocate the system‐wide inventory across the different facilities.We report on an extensive numerical study with close to 14 000 instances which evaluates the accuracy of the lower bound and the optimality gap of the various heuristic policies. The study reveals that the lower bound and the heuristic strategy that is constructed on its basis perform exceedingly well, almost across the entire parameter spectrum, including instances where demands are rather volatile or the average cycle time between consecutive orders is relatively large. The exception arises when storage at the depot is as expensive as at the retailer level and the retailers have large storage capacities.
Coupled Atmosphere‐Fire Simulations of the Black Saturday Kilmore East Wildfires With the Unified Model
Authors: Toivanen Jussi , Engel Chermelle B. , Reeder Michael J. , Lane Todd P. , Davies Laura , Webster Stuart , Wales Scott 
Published: December 2018

AbstractA model for the spread of a wildfire is developed within the U.K. Met Office Unified Model (UM) and used to simulate the Kilmore East fire complex (in southeastern Australia) on Black Saturday (7 February 2009). The UM is configured with four nests with horizontal grid spacings of 4 km, 1.5 km, 444 m, and 144 m. In the first simulation, the UM simply provides predictions of the near‐surface conditions for the wildfire model with no feedbacks to the atmosphere from the fire. In the second, the atmosphere and fire are coupled, allowing the fire to affect the local‐scale weather. The agreement between the coupled simulation and the observed fire behavior is reasonably good. For example, the area burnt is approximately 80% of the actual area burnt. However, such agreement is achieved only by coupling the fire to the atmosphere and, importantly, by igniting 18 additional fires at the times and places the long‐range transport of burning material (spotting) was observed. Without coupling the burnt area is about half of that observed. The calculations reported here suggest that the behavior and spread of fires like the Kilmore East fire are predictable but only when long‐range spotting is included and the atmosphere and fires are coupled. Additional numerical experiments with coarser grids suggest that, although the details of the fire spread are lost, a grid spacing of 1.5 km may be sufficient to simulate the main features of the fire spread.
High‐Resolution Observations of Subsurface Fronts and Alongshore Bottom Temperature Variability Over the Inner Shelf
Authors: Connolly Thomas P. , Kirincich Anthony R. 
Published: December 2018

AbstractCirculation patterns over the inner continental shelf can be spatially complex and highly variable in time. However, few studies have examined alongshore variability over short scales of kilometers or less. To observe inner‐shelf bottom temperatures with high (5‐m) horizontal resolution, a fiber‐optic distributed temperature sensing system was deployed along a 5‐km‐long portion of the 15‐m isobath within a larger‐scale mooring array south of Martha's Vineyard, MA. Over the span of 4 months, variability at a range of scales was observed along the cable over time periods of less than a day. Notably, rapid cooling events propagated down the cable away from a tidal mixing front, showing that propagating fronts on the inner shelf can be generated locally near shallow bathymetric features in addition to remote offshore locations. Propagation velocities of observed fronts were influenced by background tidal currents in the alongshore component and show a weak correlation with theoretical gravity current speeds in the cross‐shore component. These events provide a source of cold, dense water into the inner shelf. However, differences in the magnitude and frequency of cooling events at sites separated by a few kilometers in the alongshore direction suggest that the characteristics of small‐scale variability can vary dramatically and can result in differential fluxes of water, heat, and other tracers. Thus, under stratified conditions, prolonged subsurface observations with high spatial and temporal resolution are needed to characterize the implications of three‐dimensional circulation patterns on exchange, especially in regions where the coastline and isobaths are not straight.
The Vertical Momentum Budget of Shallow Cumulus Convection: Insights From a Lagrangian Perspective
Authors: Tian Yang , Kuang Zhiming , Singh Martin S. , Nie Ji 
Published: December 2018

AbstractA Lagrangian Particle Dispersion Model is embedded into large eddy simulations to diagnose the responses of shallow cumulus convection to a small‐amplitude large‐scale temperature perturbation. The Lagrangian framework allows for a decomposition of the vertical momentum budget and diagnosis of the forces that regulate cloudy updrafts. The results are used to shed light on the parameterization of vertical velocity in convective schemes, where the treatment of the effects of entrainment as well as buoyancy‐induced and mechanically induced pressure gradients remains highly uncertain. We show that both buoyancy‐induced and mechanically induced pressure gradients are important for the vertical momentum budget of cloudy updrafts, whereas the entrainment dilution term is relatively less important. Based on the analysis of the dominant force balance, we propose a simple model to derive the perturbation pressure gradient forces. We further illustrate that the effective buoyancy and dynamic perturbation pressure can be approximated to a good extent using a simple cylindrical updraft model given the cloud radius. This finding has the potential for improving the parameterization of vertical velocity in convective schemes and the development of a unified scheme for cumulus convection.
Evaluating Marine Stratocumulus Clouds in the CNRM‐CM6‐1 Model Using Short‐Term Hindcasts
Authors: Brient Florent , Roehrig Romain , Voldoire Aurore 
Published: December 2018

AbstractThe representation of stratocumulus by the atmospheric component of the Centre National de Recherches Météorologiques model version 6 (CNRM‐CM6‐1) is assessed. An Atmospheric Model Intercomparison Project‐type simulation is first used to document the main model errors, namely, a large lack of stratocumulus over the eastern part of tropical ocean basins. Short‐term hindcasts, following the Transpose‐Atmospheric Model Intercomparison Project framework, are then used to better assess the timescales associated with the cloud bias growth and to highlight the processes leading to them. These biases are shown to appear within only a few hours, independently of errors in the large‐scale circulation that set up within a few days. Key processes underlying the low‐cloud formation are thus mainly local and, to the first order, do not imply any feedback between the model physics and the large‐scale dynamics. As a consequence, short‐term hindcasts provide a relevant framework to investigate whether the low‐cloud underestimate is related to errors in the large‐scale state variables or to errors in the model parameterizations. Sensitivity tests highlight that the involved processes arise (1) mostly from misrepresentation of subgrid effects on cloud formation and (2) partly from biases in drying induced by cloud‐top entrainment mixing. Improvements in the representation of stratocumulus in the CNRM‐CM6‐1 model might thus be expected by including a more realistic subgrid‐scale temperature and moisture distribution, that would link convective and turbulence processes. Finally, this study confirms the potential of short‐term hindcasts, which provide a trustworthy framework to evaluate and develop climate model parameterizations.
A T-cell receptor escape channel allows broad T-cell response to CD1b and membrane phospholipids
Authors: Shahine Adam , Reinink Peter , Reijneveld Josephine F. , Gras Stephanie , Holzheimer Mira , Cheng Tan-Yun , Minnaard Adriaan J. , Altman John D. , Lenz Steffi , Prandi Jacques , Kubler-Kielb Joanna , Moody D. Branch , Rossjohn Jamie , Van Rhijn Ildiko 
Published: December 2018

AbstractCD1 proteins are expressed on dendritic cells, where they display lipid antigens to T-cell receptors (TCRs). Here we describe T-cell autoreactivity towards ubiquitous human membrane phospholipids presented by CD1b. These T-cells discriminate between two major types of lipids, sphingolipids and phospholipids, but were broadly cross-reactive towards diverse phospholipids including phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine. The crystal structure of a representative TCR bound to CD1b-phosphatidylcholine provides a molecular mechanism for this promiscuous recognition. We observe a lateral escape channel in the TCR, which shunted phospholipid head groups sideways along the CD1b-TCR interface, without contacting the TCR. Instead the TCR recognition site involved the neck region phosphate that is common to all major self-phospholipids but absent in sphingolipids. Whereas prior studies have focused on foreign lipids or rare self-lipids, we define a new molecular mechanism of promiscuous recognition of common self-phospholipids including those that are known targets in human autoimmune disease.
Discoidin-domain receptor coordinates cell-matrix adhesion and collective polarity in migratory cardiopharyngeal progenitors
Authors: Bernadskaya Yelena Y. , Brahmbhatt Saahil , Gline Stephanie E. , Wang Wei , Christiaen Lionel 
Published: December 2018

AbstractIntegrated analyses of regulated effector genes, cellular processes, and extrinsic signals are required to understand how transcriptional networks coordinate fate specification and cell behavior during embryogenesis. Ciona cardiopharyngeal progenitors, the trunk ventral cells (TVCs), polarize as leader and trailer cells that migrate between the ventral epidermis and trunk endoderm. We show that the TVC-specific collagen-binding Discoidin-domain receptor (Ddr) cooperates with Integrin-β1 to promote cell-matrix adhesion. We find that endodermal cells secrete a collagen, Col9-a1, that is deposited in the basal epidermal matrix and promotes Ddr activation at the ventral membrane of migrating TVCs. A functional antagonism between Ddr/Intβ1-mediated cell-matrix adhesion and Vegfr signaling appears to modulate the position of cardiopharyngeal progenitors between the endoderm and epidermis. We show that Ddr promotes leader-trailer-polarized BMP-Smad signaling independently of its role in cell-matrix adhesion. We propose that dual functions of Ddr integrate transcriptional inputs to coordinate subcellular processes underlying collective polarity and migration.
Thromboembolism in Pregnancy: Gynecologists Perspective
Authors: Hari Anupama 
Published: December 2018

AbstractPregnancy is a thrombogenic condition in both antenatal and postpartum periods. Venous thromboembolism (VTE) is a common cause of morbidity, and the cause of maternal death in such situations is pulmonary embolism. There are several risk factors for thrombotic phenomena in pregnancy both acquired and hereditary. Accurate diagnosis of deep vein thrombosis (DVT) and its treatment are very important to prevent life-threatening pulmonary embolism. Among the diagnostic techniques, compression ultrasound is the mainstay for DVT diagnosis, whereas computed tomographic pulmonary angiography (CTPA) is for pulmonary embolism. Anticoagulants play a major role in therapy. They are used both in the active stage of thromboembolism and also in thromboprophylaxis in the postpartum period. Different types of heparins are available, which can be tailored to the individual requirements. During therapy they need monitoring to prevent hemorrhagic complications. Oral anticoagulants cannot be given in pregnancy as a general rule because of their teratogenicity, though they can be used in the postpartum period. Thrombolysis is can be taken up in selected cases in the acute situations. A very prolonged treatment of anticoagulants and compression stockings are needed in patients with past history of VTE. The most convenient drug regimen for prophylaxis is once-daily weight-adjusted low-molecular-weight heparin (LMWH). The goal of this article is to facilitate the recognition of thromboembolic disorders in pregnancy and different regimens in their management during antenatal, intrapartum, and postpartum periods. A few interesting and rare cases from the author’s experience are also presented at the end.
Cardiovascular Diseases of Genetic Etiology and Implications for the Pregnant Woman
Authors: Aggarwal Shagun 
Published: December 2018

AbstractPregnancy presents a unique hemodynamic challenge to women with cardiovascular disorders of genetic etiology. Many such women undergo decompensation during pregnancy or have acute cardiac events. In addition, there is a risk of transmission of the disease to the fetus, which warrants prenatal testing using invasive and noninvasive means. This article provides an overview of the management issues of these women during pregnancy.
Structural Heart Diseases during Pregnancy: Part 1—Valvular Heart Diseases
Authors: Patnaik Amar 
Published: December 2018

AbstractIt is estimated that about 3% pregnancies can have cardiac disease. There is wide variation in the spectrum of heart diseases. Pregnant women in India and other developing countries continue to show high prevalence of rheumatic heart disease (RHD). Pre-conception counseling based on a good echocardiographic evaluation is the most cost-effective method to prevent morbidity and mortality due to valvular heart disease. With advances in medical science, many with valvular heart disease are living to adulthood and undergoing successful pregnancy. Symptoms of a pregnant woman with a valvular disease depend on the altered hemodynamics of the specific valvular lesion in combination with the physiologic changes inherent to the pregnancy itself. A good echocardiographic evaluation of all pregnant women on their first visit to an obstetrician’s office is an effective strategy to prevent morbidity and mortality from valvular heart diseases. In general, the regurgitant lesions are well tolerated during pregnancy and labor. Asymptomatic but significant valve lesions can be decompensated by many factors. Severely stenosed mitral and, sometimes, aortic valve may have to be balloon-dilated by trained experts in midterm taking due care to avoid excess radiation. Valve surgery is rarely performed in absence of any other safer option. A multidisciplinary team approach is required to manage a pregnant woman with significant cardiac lesion with high-risk features and patients having mechanical valves that require continuous anticoagulation.
Anesthetic Management and Perioperative Events of Peripartum Cardiomyopathy during Cesarean Delivery a Series of Five Cases
Authors: Mellacheruvu Sree Rama , Chakravarthy Kousalya , Ahmed Khaliq 
Published: December 2018

AbstractPeripartum cardiomyopathy (PPCM) is a rare idiopathic cardiomyopathy having an incidence of less than 0.1%. PPCM is associated with high morbidity and mortality rates ranging from 5 to 32%. In this review, the authors report a series of five PPCM cases. The case reports included pregnant women with PPCM, admitted in the hospital from October 1, 2017 to June 1, 2018 over a period of 9 months who required cesarean section. The authors aim to discuss the presentation, optimization, anesthetic management, and postoperative care of this rare condition. One of the cases was a booked case. The remaining four pregnant patients were referred in late pregnancy with features of congestive cardiac failure. One patient was in acute pulmonary edema, required intubation, and subsequently had cesarean section under general anesthesia. Four patients were managed with incremental epidural anesthesia. The need for proper preoperative optimization and intra- and postoperative management was discussed. The authors had one maternal mortality in our series. There was no neonatal mortality. Early diagnosis of PPCM, prompt treatment of heart failure, planning the delivery, and postpartum care can decrease maternal morbidity and mortality. Incremental epidural dosing can be used for cesarean section and has the advantage of stable hemodynamic status without the risks associated with general anesthesia.
Physiological Changes in Cardiovascular System during Normal Pregnancy: A Review
Authors: Taranikanti Madhuri 
Published: December 2018

AbstractPregnancy is a complex biological process associated with changes in physiologic functions of the body. Dramatic changes take place in the cardiovascular physiology leading to gradual adaptation of these changes by the body of the pregnant woman. Cardiac output increases during pregnancy to 30 to 50% above the prepregnant levels. The increase in cardiac output occurs due to increase in stroke volume initially during gestation and later by increase in heart rate. These changes in cardiac output are attributed to either neurohumoral factors such as estrogen and progesterone or placental factors. Maternal body position affects cardiac output with highest in kneel-chest and left lateral positions. Along with these changes, variations in heart rate, blood pressure, and blood volume are observed following a specific pattern of change during pregnancy. Hence, it is necessary to understand the cardiovascular changes during pregnancy to interpret, predict, and diagnose any cardiac disease efficiently.
Heart Failure in Pregnancy
Authors: Mahilmaran Asha 
Published: December 2018

AbstractCardiovascular mortality remains an important cause of maternal mortality other than the obstetric direct causes. Most cardiovascular deaths occur due to heart failure. Rheumatic heart diseases (RHD) account for more than two-thirds of heart diseases in pregnancy in low–middle income countries. Among RHD patients, 49% of patients with severe mitral stenosis, 31% with moderate mitral stenosis, and 23% with moderate to severe mitral regurgitation present with heart failure during pregnancy. In the U.K. registry, 25% of patients had heart failure due to cardiomyopathy. Congenital heart diseases such as atrial septal defect with severe pulmonary hypertension, significant atrioventricular valve regurgitation, peripartum, or dilated cardiomyopathy are less common causes of heart failure in pregnancy. Coronary artery diseases usually present as acute coronary syndromes during pregnancy, and heart failure as presentation is a rare occurrence. Preeclampsia and chronic hypertension can lead to increased vascular resistance, diastolic dysfunction, acute pulmonary edema, and acute heart failure. Two-thirds of heart diseases are diagnosed during the antepartum period itself. Preconception counseling, optimal medical therapy and avoidance of teratogens, and planning interventional or surgical therapies in patients with severe or moderate valvular diseases and congenital heart diseases will enable patients to enter the pregnancy well compensated. During pregnancy and postpartum, close surveillance and a multidisciplinary approach involving the obstetrician, cardiologist, physician, and anesthetist will lead to better maternal and fetal outcomes.
Maternal Outcome in Mitral Valve Disease with Pulmonary Hypertension: Two Case Reports
Authors: Alagandala Anuradha , Vaswani Daya , Bharadwaj Vuduthala , Chakravarthy Kousalya 
Published: December 2018

AbstractChronic rheumatic heart disease is still the leading cause of heart disease complicating pregnancy in the developing countries. The physiologic changes in pregnancy and stress induced by the increase in cardiac output can cause asymptomatic patients with mitral stenosis to decompensate, especially in the third trimester. Severity of mitral stenosis is reflected by the decrease in the valve area and increase in the right ventricular systolic pressures (RVSPs). Venous thromboembolism (VTE) is two to five times more common in the postpartum period, and the risk is high with cesarean delivery. Pulmonary embolism in pregnancy can cause severe maternal morbidity and mortality. We describe two cases of severe mitral stenosis complicating pregnancy with grossly elevated RVSP. The first case is the successful management of a second gravida, presenting with severe mitral stenosis with RVSP 80 mm Hg, and the second, a fatal case of a 26-year-old para 1, live 1, delivered by cesarean section, presenting with massive fatal pulmonary embolism on 13th postoperative day (POD) with RVSP 90 mm Hg. A multidisciplinary approach involving the cardiologist, obstetrician, and obstetric anesthesiologist is crucial for management of severe mitral stenosis complicating pregnancy, to decrease the maternal morbidity and mortality during peripartum period.