bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitigation of overburden effects in fracture prediction using azimuthal AVO analysis: An example from a Middle East carbonate field
Authors: Liu Enru , Zelewski Gregg , Lu Chih-Ping , Reilly Joseph M. , Shevchek Zygmount J.
Published: July 2011

The ability to identify fracture clusters and corridors and their prevalent direction within many carbonates and unconventional shale gas/tight gas reservoirs may have a significant impact on field development planning as well as on the placement of individual wells. We believe seismic fracture prediction provides the best opportunity to identify the spatial distribution of fracture corridors, but the reliability of seismic fracture detection technology is constantly being questioned. The criticism results from the degree to which the acquisition footprint, random and coherent noise in the seismic data, and near-surface/overburden issues affect extracted seismic “fracture” attributes. Therefore, a key issue is the separation of artifacts caused by the acquisition footprint and near-surface or overburden anisotropy/structural variations from the anomalies caused by the presence of fractures.
Seismic reservoir characterization in resource shale plays: Stress analysis and sweet spot discrimination
Authors: Sena Arcangelo , Castillo Gabino , Chesser Kevin , Voisey Simon , Estrada Jorge , Carcuz Juan , Carmona Emilio , Hodgkins Peggy
Published: July 2011

Surface seismic data have proven to be an invaluable asset for organizations producing hydrocarbons from unconventional resource plays. Initially, a primary benefit of surface seismic was the ability to locate and avoid drilling into zones with faults, fractures, and karsting which adversely affected the ability to complete the well successfully. More recent advances in prestack seismic data analysis yield attributes that appear to be correlated to formation lithology, rock strength, and stress fields. Knowledge and proper utilization of these attributes may prove valuable in the optimization of drilling and completion activities.
Seismic anisotropy in microseismic event location analysis
Authors: Van Dok Richard , Fuller Brian , Engelbrecht Les , Sterling Marc
Published: July 2011

Seismic velocity anisotropy has been known for many years to be an important factor in correctly imaging subsurface structures with reflection seismic methods (Alkhalifah et al., 1996). Fine vertical velocity layering naturally gives rise to VTI (vertical transverse isotropic) velocity in which seismic-wave velocity is faster in the horizontal direction than in the vertical direction. Similarly, vertically oriented natural fractures and stress fields influence seismic velocities in an azimuthal or compass direction which is described as HTI (horizontal transverse isotropic) velocity variation (Schoenberg and Sayers, 1995). HTI velocity analysis in seismic reflection imaging commonly has two main objectives: placing geologic features in the correct spatial location and characterizing fracture orientation and density to optimize oil and gas production strategy.
Effective VTI anisotropy for consistent monitoring of microseismic events
Authors: Eisner Leo , Zhang Yang , Duncan Peter , Mueller Michael C. , Thornton Michael P. , Gei Davide
Published: July 2011

The monitoring of induced or triggered microseismic events increasingly is being used to inform the efficient production of unconventional reservoirs. A key aspect of economic production in these low-permeability rocks is hydraulic fracture stimulation, usually in horizontal wells. To evaluate the success of the stimulation, engineers rely on monitoring the induced (or triggered) microseismic events that are then interpreted to map the stimulated reservoir volume and likely drainage area of the well. These microseismic events can be mapped either from downhole or surface monitoring arrays. In this study, we discuss a newly developed methodology that allows economic and consistent mapping of microseismic events from multiple stimulated wells across an entire field. This approach allows better comparison of stimulation techniques between wells in order to optimize long-term development of the reservoir. As well, the method enables a relatively robust observation of velocity anisotropy that leads to better wave-propagation modeling and more accurate event locations
Microsatellite Instability and Loss of Heterozygosity at Chromosomal Location 18q: Prospective Evaluation of Biomarkers for Stages II and III Colon Cancer—A Study of CALGB 9581 and 89803
Authors: Bertagnolli Monica M. , Redston Mark , Compton Carolyn C. , Niedzwiecki Donna , Mayer Robert J. , Goldberg Richard M. , Colacchio Thomas A. , Saltz Leonard B. , Warren Robert S.
Published: July 2011

Purpose

Colorectal cancer (CRC) develops as a result of a series of accumulated genomic changes that produce oncogene activation and tumor suppressor gene loss. These characteristics may classify CRC into subsets of distinct clinical behaviors.

Patients and Methods

We studied two of these genomic defects—mismatch repair deficiency (MMR-D) and loss of heterozygosity at chromosomal location 18q (18qLOH)—in patients enrolled onto two phase III cooperative group trials for treatment of potentially curable colon cancer. These trials included prospective secondary analyses to determine the relationship between these markers and treatment outcome. A total of 1,852 patients were tested for MMR status and 955 (excluding patients with MMR-D tumors) for 18qLOH.

Results

Compared with stage III, more stage II tumors were MMR-D (21.3% v 14.4%; P < .001) and were intact at 18q (24.2% v 15.1%; P = .001). For the combined cohort, patients with MMR-D tumors had better 5-year disease-free survival (DFS; 0.76 v 0.67; P < .001) and overall survival (OS; 0.81 v 0.78; P = .029) than those with MMR intact (MMR-I) tumors. Among patients with MMR-I tumors, the status of 18q did not affect outcome, with 5-year values for patients with 18q intact versus 18qLOH tumors of 0.74 versus 0.65 (P = .18) for DFS and 0.81 versus 0.77 (P = .18) for OS.

Conclusion

We conclude that MMR-D tumor status, but not the presence of 18qLOH, has prognostic value for stages II and III colon cancer.
Compendium of Unpublished Phase III Trials in Oncology: Characteristics and Impact on Clinical Practice
Authors: Tam Vincent C. , Tannock Ian F. , Massey Christine , Rauw Jennifer , Krzyzanowska Monika K.
Published: July 2011

Purpose

Many phase III trials presented at annual meetings of the American Society of Clinical Oncology (ASCO) remain unpublished. The results of these unpublished trials, if more generally known, might have an impact on clinical practice.

Methods

Abstracts of large phase III trials evaluating systemic cancer treatment were identified from conference proceedings of the 1989 to 2003 ASCO annual meetings. PubMed, Medline, and Embase were searched for corresponding publications. A compendium of unpublished phase III trials was assembled. Clinical significance of nonpublication was determined by disease site-specific oncology experts from two academic cancer centers in Canada.

Results

A total of 709 phase III trials were identified of which 66 (9.3%) remain without a subsequent publication at a minimum of 6.5 years of follow-up and 94 (13%) were published after a delay of ≥ 5 years from their initial presentation. Of the unpublished trials, 48% were presented as oral sessions at an ASCO meeting, and 71% of the abstracts reported negative results. The experts judged that 70% of the unpublished trials addressed an important question and 59% might have had clinical impact if their results had been published promptly.

Conclusion

A substantial number of cancer clinical trials with potential influence on clinical practice remain unpublished and many other trials are published after a substantial delay. Nonpublication of clinical trials breaks an implicit contract with participants, institutional review boards, and sponsors.
Randomized Phase II Study of Pemetrexed, Carboplatin, and Thoracic Radiation With or Without Cetuximab in Patients With Locally Advanced Unresectable Non–Small-Cell Lung Cancer: Cancer and Leukemia Group B Trial 30407
Authors: Govindan Ramaswamy , Bogart Jeffrey , Stinchcombe Thomas , Wang Xiaofei , Hodgson Lydia , Kratzke Robert , Garst Jennifer , Brotherton Timothy , Vokes Everett E.
Published: July 2011

Purpose

Cancer and Leukemia Group B conducted a randomized phase II trial to investigate two novel chemotherapy regimens in combination with concurrent thoracic radiation therapy (TRT).

Patients and Methods

Patients with unresectable stage III non–small-cell lung cancer (NSCLC) were randomly assigned to carboplatin (area under the curve, 5) and pemetrexed (500 mg/m2) every 21 days for four cycles and TRT (70 Gy; arm A) or the same treatment with cetuximab administered concurrent only with TRT (arm B). Patients in both arms received up to four cycles of pemetrexed as consolidation therapy. The primary end point was the 18-month overall survival (OS) rate; if the 18-month OS rate was ≥ 55%, the regimen(s) would be considered for further study.

Results

Of the 101 eligible patients enrolled (48 in arm A and 53 in arm B), 60% were male; the median age was 66 years (range, 32 to 81 years); 44% and 35% had adenocarcinoma and squamous carcinoma, respectively; and more patients enrolled onto arm A compared with arm B had a performance status of 0 (58% v 34%, respectively; P = .04). The 18-month OS rate was 58% (95% CI, 46% to 74%) in arm A and 54% (95% CI, 42% to 70%) in arm B. No significant difference in OS between patients with squamous and nonsquamous NSCLC was observed (P = .667). The toxicities observed were consistent with toxicities associated with concurrent chemoradiotherapy.

Conclusion

The combination of pemetrexed, carboplatin, and TRT met the prespecified criteria for further evaluation. This regimen should be studied further in patients with locally advanced unresectable nonsquamous NSCLC.
Positron Emission Tomography–Computed Tomography (PET-CT) After Induction Therapy Is Highly Predictive of Patient Outcome in Follicular Lymphoma: Analysis of PET-CT in a Subset of PRIMA Trial Participants
Authors: Trotman Judith , Fournier Marion , Lamy Thierry , Seymour John Francis , Sonet Anne , Janikova Andrea , Shpilberg Ofer , Gyan Emmanuel , Tilly Hervé , Estell Jane , Forsyth Cecily , Decaudin Didier , Fabiani Bettina , Gabarre Jean , Salles Bruno , Van Den Neste Eric , Canioni Danielle , Garin Etienne , Fulham Michael , Vander Borght Thierry , Salles Gilles
Published: July 2011

Purpose

The utility of [18F]fluorodeoxyglucose (FDG) positron emission tomography–computed tomography (PET-CT) in assessing response at the end of induction therapy is well documented in Hodgkin's and diffuse large B-cell lymphomas, but its role in follicular lymphoma (FL) remains undetermined. We investigated the prognostic significance of PET-CT performed after first-line therapy in patients with FL treated in the prospective Primary Rituximab and Maintenance (PRIMA) study.

Patients and Methods

Results of PET-CT scans performed after induction immunochemotherapy were recorded retrospectively. Patients went on to either observation or rituximab maintenance per protocol independent of the PET-CT result. Patient characteristics and outcomes were then evaluated.

Results

Of 122 PET-CT scans performed at the end of the induction immunochemotherapy, 32 (26%) were reported as positive by the local investigator. Initial demographic or disease characteristics did not differ between PET-CT–positive (PET-positive) and PET-CT–negative (PET-negative) patients. PET status correlated with conventional response criteria (P < .001). Patients remaining PET positive had a significantly (P < .001) inferior progression-free survival at 42 months of 32.9% (95% CI, 17.2% to 49.5%) compared with 70.7% (95% CI, 59.3% to 79.4%) in those who became PET negative. PET status, but not conventional response (complete response or complete response unconfirmed v partial response) according to IWC 1999, was an independent predictive factor for lymphoma progression. The risk of death was also increased in PET-positive patients (hazard ratio 7.0; P = .0011).

Conclusion

[18F]FDG PET-CT status at the end of immunochemotherapy induction in patients with FL is strongly predictive of outcome and should be considered a meaningful clinical end point in future studies.
Regulation of spinal interneuron development by the Olig-related protein Bhlhb5 and Notch signaling
Authors: Skaggs Kaia , Martin Donna M. , Novitch Bennett G.
Published: July 2011

The neural circuits that control motor activities depend on the spatially and temporally ordered generation of distinct classes of spinal interneurons. Despite the importance of these interneurons, the mechanisms underlying their genesis are poorly understood. Here, we demonstrate that the Olig-related transcription factor Bhlhb5 (recently renamed Bhlhe22) plays two central roles in this process. Our findings suggest that Bhlhb5 repressor activity acts downstream of retinoid signaling and homeodomain proteins to promote the formation of dI6, V1 and V2 interneuron progenitors and their differentiated progeny. In addition, Bhlhb5 is required to organize the spatially restricted expression of the Notch ligands and Fringe proteins that both elicit the formation of the interneuron populations that arise adjacent to Bhlhb5+ cells and influence the global pattern of neuronal differentiation. Through these actions, Bhlhb5 helps transform the spatial information established by morphogen signaling into local cell-cell interactions associated with Notch signaling that control the progression of neurogenesis and extend neuronal diversity within the developing spinal cord.
The L6 domain tetraspanin Tm4sf4 regulates endocrine pancreas differentiation and directed cell migration
Authors: Anderson Keith R. , Singer Ruth A. , Balderes Dina A. , Hernandez-Lagunas Laura , Johnson Christopher W. , Artinger Kristin B. , Sussel Lori
Published: July 2011

The homeodomain transcription factor Nkx2.2 is essential for pancreatic development and islet cell type differentiation. We have identified Tm4sf4, an L6 domain tetraspanin family member, as a transcriptional target of Nkx2.2 that is greatly upregulated during pancreas development in Nkx2.2–/– mice. Tetraspanins and L6 domain proteins recruit other membrane receptors to form active signaling centers that coordinate processes such as cell adhesion, migration and differentiation. In this study, we determined that Tm4sf4 is localized to the ductal epithelial compartment and is prominent in the Ngn3+ islet progenitor cells. We also established that pancreatic tm4sf4 expression and regulation by Nkx2.2 is conserved during zebrafish development. Loss-of-function studies in zebrafish revealed that tm4sf4 inhibits α and β cell specification, but is necessary for ε cell fates. Thus, Tm4sf4 functional output opposes that of Nkx2.2. Further investigation of how Tm4sf4 functions at the cellular level in vitro showed that Tm4sf4 inhibits Rho-activated cell migration and actin organization in a ROCK-independent fashion. We propose that the primary role of Nkx2.2 is to inhibit Tm4sf4 in endocrine progenitor cells, allowing for delamination, migration and/or appropriate cell fate decisions. Identification of a role for Tm4sf4 during endocrine differentiation provides insight into islet progenitor cell behaviors and potential targetable regenerative mechanisms.
Wnt6 activates endoderm in the sea urchin gene regulatory network
Authors: Croce Jenifer , Range Ryan , Wu Shu-Yu , Miranda Esther , Lhomond Guy , Peng Jeff Chieh-fu , Lepage Thierry , McClay David R.
Published: July 2011

In the sea urchin, entry of β-catenin into the nuclei of the vegetal cells at 4th and 5th cleavages is necessary for activation of the endomesoderm gene regulatory network. Beyond that, little is known about how the embryo uses maternal information to initiate specification. Here, experiments establish that of the three maternal Wnts in the egg, Wnt6 is necessary for activation of endodermal genes in the endomesoderm GRN. A small region of the vegetal cortex is shown to be necessary for activation of the endomesoderm GRN. If that cortical region of the egg is removed, addition of Wnt6 rescues endoderm. At a molecular level, the vegetal cortex region contains a localized concentration of Dishevelled (Dsh) protein, a transducer of the canonical Wnt pathway; however, Wnt6 mRNA is not similarly localized. Ectopic activation of the Wnt pathway, through the expression of an activated form of β-catenin, of a dominant-negative variant of GSK-3β or of Dsh itself, rescues endomesoderm specification in eggs depleted of the vegetal cortex. Knockdown experiments in whole embryos show that absence of Wnt6 produces embryos that lack endoderm, but those embryos continue to express a number of mesoderm markers. Thus, maternal Wnt6 plus a localized vegetal cortical molecule, possibly Dsh, is necessary for endoderm specification; this has been verified in two species of sea urchin. The data also show that Wnt6 is only one of what are likely to be multiple components that are necessary for activation of the entire endomesoderm gene regulatory network.
Universal patterns of stem cell fate in cycling adult tissues
Authors: Klein Allon M. , Simons Benjamin D.
Published: July 2011

In cycling tissues that exhibit high turnover, tissue maintenance and repair are coordinated by stem cells. But, how frequently stem cells are replaced following differentiation, aging or injury remains unclear. By drawing together the results of recent lineage-tracing studies, we propose that tissue stem cells are routinely lost and replaced in a stochastic manner. We show that stem cell replacement leads to neutral competition between clones, resulting in two characteristic and recurring patterns of clone fate dynamics, which provide a unifying framework for interpreting clone fate data and for measuring rates of stem cell loss and replacement in vivo. Thus, we challenge the concept of the stem cell as an immortal, slow-cycling, asymmetrically dividing cell.
Generation of mice with functional inactivation oftalpid3, a gene first identified in chicken
Authors: Bangs Fiona , Antonio Nicole , Thongnuek Peerapat , Welten Monique , Davey Megan G. , Briscoe James , Tickle Cheryll
Published: July 2011

Specification of digit number and identity is central to digit pattern in vertebrate limbs. The classical talpid3 chicken mutant has many unpatterned digits together with defects in other regions, depending on hedgehog (Hh) signalling, and exhibits embryonic lethality. The talpid3 chicken has a mutation in KIAA0586, which encodes a centrosomal protein required for the formation of primary cilia, which are sites of vertebrate Hh signalling. The highly conserved exons 11 and 12 of KIAA0586 are essential to rescue cilia in talpid3 chicken mutants. We constitutively deleted these two exons to make a talpid3–/– mouse. Mutant mouse embryos lack primary cilia and, like talpid3 chicken embryos, have face and neural tube defects but also defects in left/right asymmetry. Conditional deletion in mouse limb mesenchyme results in polydactyly and in brachydactyly and a failure of subperisoteal bone formation, defects that are attributable to abnormal sonic hedgehog and Indian hedgehog signalling, respectively. Like talpid3 chicken limbs, the mutant mouse limbs are syndactylous with uneven digit spacing as reflected in altered Raldh2 expression, which is normally associated with interdigital mesenchyme. Both mouse and chicken mutant limb buds are broad and short. talpid3–/– mouse cells migrate more slowly than wild-type mouse cells, a change in cell behaviour that possibly contributes to altered limb bud morphogenesis. This genetic mouse model will facilitate further conditional approaches, epistatic experiments and open up investigation into the function of the novel talpid3 gene using the many resources available for mice.
Barx2 and Fgf10 regulate ocular glands branching morphogenesis by controlling extracellular matrix remodeling
Authors: Tsau Cindy , Ito Masataka , Gromova Anastasia , Hoffman Matthew P. , Meech Robyn , Makarenkova Helen P.
Published: July 2011

The lacrimal gland (LG) develops through branching morphogenesis and produces secretions, including tears, that lubricate and protect the ocular surface. Despite the prevalence of LG disorders such as dry eye, relatively little is known about the regulation of LG development. In this study, we show that the homeobox transcription factor Barx2 is highly expressed in conjunctival epithelium, eyelids and ocular [lacrimal, harderian (HG), and meibomian (MG)] glands and is necessary for normal ocular gland and eyelid development. Barx2–/– mice show defective LG morphogenesis, absence of the HG, and defects in MG and eyelid fusion. Ex vivo antisense assays confirm the requirement for Barx2 in LG bud elongation and branching. Gene expression profiles reveal decreased expression of several adhesion and matrix remodeling molecules in Barx2–/– LGs. In culture, Barx2 regulates expression of matrix metalloproteinases (MMPs) and epithelial cell migration through the extracellular matrix. Fibroblast growth factors are crucial regulators of LG development and we show that Barx2 is required for Fgf10-induced LG bud elongation and that both Barx2 and Fgf10 cooperate in the regulation of MMPs. Together, these data suggest a mechanism for the effects of loss of Barx2 on ocular gland development. Intriguingly, salivary glands that also express a high level of Barx2 develop normally in Barx2–/– mice and do not show altered levels of MMPs. Thus, the function of Barx2 is specific to ocular gland development. Based on our data, we propose a functional network involving Barx2, Fgf10 and MMPs that plays an essential role in regulating branching morphogenesis of the ocular glands.
A novel role for MuSK and non-canonical Wnt signaling during segmental neural crest cell migration
Authors: Banerjee Santanu , Gordon Laura , Donn Thomas M. , Berti Caterina , Moens Cecilia B. , Burden Steven J. , Granato Michael
Published: July 2011

Trunk neural crest cells delaminate from the dorsal neural tube as an uninterrupted sheet; however, they convert into segmentally organized streams before migrating through the somitic territory. These neural crest cell streams join the segmental trajectories of pathfinding spinal motor axons, suggesting that interactions between these two cell types might be important for neural crest cell migration. Here, we show that in the zebrafish embryo migration of both neural crest cells and motor axons is temporally synchronized and spatially restricted to the center of the somite, but that motor axons are dispensable for segmental neural crest cell migration. Instead, we find that muscle-specific receptor kinase (MuSK) and its putative ligand Wnt11r are crucial for restricting neural crest cell migration to the center of each somite. Moreover, we find that blocking planar cell polarity (PCP) signaling in somitic muscle cells also results in non-segmental neural crest cell migration. Using an F-actin biosensor we show that in the absence of MuSK neural crest cells fail to retract non-productive leading edges, resulting in non-segmental migration. Finally, we show that MuSK knockout mice display similar neural crest cell migration defects, suggesting a novel, evolutionarily conserved role for MuSK in neural crest migration. We propose that a Wnt11r-MuSK dependent, PCP-like pathway restricts neural crest cells to their segmental path.
Sequential Convex Approximations to Joint Chance Constrained Programs: A Monte Carlo Approach
Authors: Hong L. Jeff , Yang Yi , Zhang Liwei
Published: July 2011

When there is parameter uncertainty in the constraints of a convex optimization problem, it is natural to formulate the problem as a joint chance constrained program (JCCP), which requires that all constraints be satisfied simultaneously with a given large probability. In this paper, we propose to solve the JCCP by a sequence of convex approximations. We show that the solutions of the sequence of approximations converge to a Karush-Kuhn-Tucker (KKT) point of the JCCP under a certain asymptotic regime. Furthermore, we propose to use a gradient-based Monte Carlo method to solve the sequence of convex approximations.
Structured Replacement Policies for Components with Complex Degradation Processes and Dedicated Sensors
Authors: Elwany Alaa H. , Gebraeel Nagi Z. , Maillart Lisa M.
Published: July 2011

Failure of many engineering systems usually results from a gradual and irreversible accumulation of damage, a degradation process. Most degradation processes can be monitored using sensor technology. The resulting degradation signals are usually correlated with the degradation process. A system is considered to have failed once its degradation signal reaches a prespecified failure threshold. This paper considers a replacement problem for components whose degradation process can be monitored using dedicated sensors. First, we present a stochastic degradation modeling framework that characterizes, in real time, the path of a component's degradation signal. These signals are used to predict the evolution of the component's degradation state. Next, we formulate a single-unit replacement problem as a Markov decision process and utilize the real-time signal observations to determine a replacement policy. We focus on exponentially increasing degradation signals and show that the optimal replacement policy for this class of problems is a monotonically nondecreasing control limit policy. Finally, the model is used to determine an optimal replacement policy by utilizing vibration-based degradation signals from a rotating machinery application.
A Unified Framework for Dynamic Prediction Market Design
Authors: Agrawal Shipra , Delage Erick , Peters Mark , Wang Zizhuo , Ye Yinyu
Published: July 2011

Recently, coinciding with and perhaps driving the increased popularity of prediction markets, several novel pari-mutuel mechanisms have been developed such as the logarithmic market-scoring rule (LMSR), the cost-function formulation of market makers, utility-based markets, and the sequential convex pari-mutuel mechanism (SCPM). In this work, we present a convex optimization framework that unifies these seemingly unrelated models for centrally organizing contingent claims markets. The existing mechanisms can be expressed in our unified framework by varying the choice of a concave value function. We show that this framework is equivalent to a convex risk minimization model for the market maker. This facilitates a better understanding of the risk attitudes adopted by various mechanisms. The unified framework also leads to easy implementation because we can now find the cost function of a market maker in polynomial time by solving a simple convex optimization problem.

In addition to unifying and explaining the existing mechanisms, we use the generalized framework to derive necessary and sufficient conditions for many desirable properties of a prediction market mechanism such as proper scoring, truthful bidding (in a myopic sense), efficient computation, controllable risk measure, and guarantees on the worst-case loss. As a result, we develop the first proper, truthful, risk-controlled, loss-bounded (independent of the number of states) mechanism; none of the previously proposed mechanisms possessed all these properties simultaneously. Thus, our work provides an effective tool for designing new prediction market mechanisms. We also discuss possible applications of our framework to dynamic resource pricing and allocation in general trading markets.
OR FORUM—Little's Law as Viewed on Its 50th Anniversary
Authors: Little John D. C.
Published: July 2011

Fifty years ago, the author published a paper in Operations Research with the title, “A proof for the queuing formula: L = λW” [Little, J. D. C. 1961. A proof for the queuing formula: L = λW. Oper. Res. 9(3) 383–387]. Over the years, L = λW has become widely known as “Little's Law.” Basically, it is a theorem in queuing theory. It has become well known because of its theoretical and practical importance. We report key developments in both areas with the emphasis on practice. In the latter, we collect new material and search for insights on the use of Little's Law within the fields of operations management and computer architecture.
Dietary sodium intake regulates angiotensin II type 1, mineralocorticoid receptor, and associated signaling proteins in heart
Authors: Ricchiuti Vincent , Lapointe Nathalie , Pojoga Luminita , Yao Tham , Tran Loc , Williams Gordon H , Adler Gail K
Published: July 2011

Liberal or high-sodium (HS) intake, in conjunction with an activated renin–angiotensin–aldosterone system, increases cardiovascular (CV) damage. We tested the hypothesis that sodium intake regulates the type 1 angiotensin II receptor (AT1R), mineralocorticoid receptor (MR), and associated signaling pathways in heart tissue from healthy rodents. HS (1.6% Na+) and low-sodium (LS; 0.02% Na+) rat chow was fed to male healthy Wistar rats (n=7 animals per group). Protein levels were assessed by western blot and immunoprecipitation analysis. Fractionation studies showed that MR, AT1R, caveolin-3 (CAV-3), and CAV-1 were located in both cytoplasmic and membrane fractions. In healthy rats, consumption of an LS versus a HS diet led to decreased cardiac levels of AT1R and MR. Decreased sodium intake was also associated with decreased cardiac levels of CAV-1 and CAV-3, decreased immunoprecipitation of AT1R–CAV-3 and MR–CAV-3 complexes, but increased immunoprecipitation of AT1R/MR complexes. Furthermore, decreased sodium intake was associated with decreased cardiac extracellular signal-regulated kinase (ERK), phosphorylated ERK (pERK), and pERK/ERK ratio; increased cardiac striatin; decreased endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS (peNOS), but increased peNOS/eNOS ratio; and decreased cardiac plasminogen activator inhibitor-1. Dietary sodium restriction has beneficial effects on the cardiac expression of factors associated with CV injury. These changes may play a role in the cardioprotective effects of dietary sodium restriction.
The Δ337T mutation on the TRβ causes alterations in growth, adiposity, and hepatic glucose homeostasis in mice
Authors: Santiago L A , Santiago D A , Faustino L C , Cordeiro A , Lisboa P C , Wondisford F E , Pazos-Moura C C , Ortiga-Carvalho T M
Published: July 2011

Mice bearing the genomic mutation Δ337T on the thyroid hormone receptor β (TRβ) gene present the classical signs of resistance to thyroid hormone (TH), with high serum TH and TSH. This mutant TR is unable to bind TH, remains constitutively bound to co-repressors, and has a dominant negative effect on normal TRs. In this study, we show that homozygous (TRβΔ337T) mice for this mutation have reduced body weight, length, and body fat content, despite augmented relative food intake and relative increase in serum leptin. TRβΔ337T mice exhibited normal glycemia and were more tolerant to an i.p. glucose load accompanied by reduced insulin secretion. Higher insulin sensitivity was observed after single insulin injection, when the TRβΔ337T mice developed a profound hypoglycemia. Impaired hepatic glucose production was confirmed by the reduction in glucose generation after pyruvate administration. In addition, hepatic glycogen content was lower in homozygous TRβΔ337T mice than in wild type. Collectively, the data suggest that TRβΔ337T mice have deficient hepatic glucose production, by reduced gluconeogenesis and lower glycogen deposits. Analysis of liver gluconeogenic gene expression showed a reduction in the mRNA of phosphoenolpyruvate carboxykinase, a rate-limiting enzyme, and of peroxisome proliferator-activated receptor-γ coactivator 1α, a key transcriptional factor essential to gluconeogenesis. Reduction in both gene expressions is consistent with resistance to TH action via TRβ, reproducing a hypothyroid phenotype. In conclusion, mice carrying the Δ337T-dominant negative mutation on the TRβ are leaner, exhibit impaired hepatic glucose production, and are more sensitive to hypoglycemic effects of insulin.
Perinatal and Neonatal Risk Factors for Autism: A Comprehensive Meta-analysis
Authors: Gardener Hannah , Spiegelman Donna , Buka Stephen L.
Published: July 2011

BACKGROUND:

The etiology of autism is unknown, although perinatal and neonatal exposures have been the focus of epidemiologic research for over 40 years.

OBJECTIVE:

To provide the first review and meta-analysis of the association between perinatal and neonatal factors and autism risk.

METHODS:

PubMed, Embase, and PsycInfo databases were searched for studies that examined the association between perinatal and neonatal factors and autism through March 2007. Forty studies were eligible for the meta-analysis. For each exposure, a summary effect estimate was calculated using a random-effects model. Heterogeneity in effect estimates across studies was examined, and, if found, a meta-regression was conducted to identify measured methodological factors that could explain between-study variability.

RESULTS:

Over 60 perinatal and neonatal factors were examined. Factors associated with autism risk in the meta-analysis were abnormal presentation, umbilical-cord complications, fetal distress, birth injury or trauma, multiple birth, maternal hemorrhage, summer birth, low birth weight, small for gestational age, congenital malformation, low 5-minute Apgar score, feeding difficulties, meconium aspiration, neonatal anemia, ABO or Rh incompatibility, and hyperbilirubinemia. Factors not associated with autism risk included anesthesia, assisted vaginal delivery, postterm birth, high birth weight, and head circumference.

CONCLUSIONS:

There is insufficient evidence to implicate any 1 perinatal or neonatal factor in autism etiology, although there is some evidence to suggest that exposure to a broad class of conditions reflecting general compromises to perinatal and neonatal health may increase the risk. Methodological variations were likely sources of heterogeneity of risk factor effects across studies.
Simulation in Pediatrics: The Reliability and Validity of a Multiscenario Assessment
Authors: McBride Mary E. , Waldrop William B. , Fehr James J. , Boulet John R. , Murray David J.
Published: July 2011

OBJECTIVE:

The goal of this study was to develop an inventory of simulated scenarios that mimic pediatric crises and determine if the resident scores could be used to establish the reliability and validity of a multiple-scenario assessment. The long-term objective is to provide pediatric residents with experiences in the recognition, diagnosis, and management of a range of simulated acute conditions.

METHODS:

Twenty scenarios were constructed. Each resident participated in 10 scenarios that were scored by 2 independent raters using an action-item checklist and a global score. Debriefing occurred after each scenario. Several analyses were performed to investigate the psychometric adequacy of the scores.

RESULTS:

Twenty-nine residents participated. The residents' scores in both sets of 10 scenarios were reliable when using either the checklist or global scoring method (>0.79). Generalizability analyses indicated that the major source of variance in scores was attributable to the scenario and scenario-resident interaction. The variance attributable to the rater was low, yielding high interrater reliability values. The more-experienced residents who participated in the study outperformed the less-experienced interns.

CONCLUSIONS:

An inventory of critical events was designed to assess pediatric residents' diagnostic and management skills. A reliable measure of ability could be obtained, provided the residents managed multiple scenarios. The residents outscored the interns, providing evidence to support the construct validity of the scores. Additional validity evidence is needed, including studies to determine if this type of training improves physicians' management of real-life critical events.
Prediction of Pneumonia in a Pediatric Emergency Department
Authors: Neuman Mark I. , Monuteaux Michael C. , Scully Kevin J. , Bachur Richard G.
Published: July 2011

OBJECTIVE:

To study the association between historical and physical examination findings and radiographic pneumonia in children who present with suspicion for pneumonia in the emergency department, and to develop a clinical decision rule for the use of chest radiography.

METHODS:

We conducted a prospective cohort study in an urban pediatric emergency department of patients younger than 21 who had a chest radiograph performed for suspicion of pneumonia (n = 2574). Pneumonia was categorized into 2 groups on the basis of an attending radiologist interpretation of the chest radiograph: radiographic pneumonia (includes definite and equivocal cases of pneumonia) and definite pneumonia. We estimated a multivariate logistic regression model with pneumonia status as the dependent variable and the historical and physical examination findings as the independent variables. We also performed a recursive partitioning analysis.

RESULTS:

Sixteen percent of patients had radiographic pneumonia. History of chest pain, focal rales, duration of fever, and oximetry levels at triage were significant predictors of pneumonia. The presence of tachypnea, retractions, and grunting were not associated with pneumonia. Hypoxia (oxygen saturation ≤92%) was the strongest predictor of pneumonia (odds ratio: 3.6 [95% confidence interval (CI): 2.0–6.8]). Recursive partitioning analysis revealed that among subjects with O2 saturation >92%, no history of fever, no focal decreased breath sounds, and no focal rales, the rate of radiographic pneumonia was 7.6% (95% CI: 5.3–10.0) and definite pneumonia was 2.9% (95% CI: 1.4–4.4).

CONCLUSION:

Historical and physical examination findings can be used to risk stratify children for risk of radiographic pneumonia.
Clinical and Microbiologic Results 12 Months After Scaling and Root Planing With Different Irrigation Solutions in Patients With Moderate Chronic Periodontitis: A Pilot Randomized Trial
Authors: Krück Carlos , Eick Sigrun , Knöfler Gerhild U. , Purschwitz Regina E. , Jentsch Holger F.R.
Published: July 2011

Background: The aim of this study is to determine in a randomized trial the impact on treatment outcome after 12 months of different subgingival irrigation solutions during scaling and root planing (SRP).

Methods: Fifty‐one adult volunteers with generalized chronic periodontitis were treated by full‐mouth SRP using 0.9% sodium chloride, 0.12% chlorhexidine digluconate, or 7.5% povidone–iodine for subgingival irrigation during SRP. Before SRP and after 3 and 12 months, probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP) were recorded. Subgingival plaque samples were analyzed for Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola.

Results: PD, CAL, and BOP were significantly improved in all groups after 12 months (P <0.001 to P = 0.044). No significant differences were seen among the groups for all sites and sites with 4 to 6 mm PD at baseline. The povidone–iodine group had the highest clinical improvements. The counts of A. actinomycetemcomitans and P. gingivalis were significantly reduced after 12 months (P = 0.045 and P = 0.002) using povidone–iodine. Significant differences between the groups were seen after 3 months for A. actinomycetemcomitans and P. gingivalis, and after 12 months for T. forsythia.

Conclusions: No differences were seen among the groups in the clinical results after 12 months. Regarding the microbiologic results, a slight benefit seemed to derive from the use of povidone–iodine.
The Impact of Local Environmental Health Capacity on Foodborne Illness Morbidity in Maryland
Authors: Zablotsky Kufel Joanna S. , Resnick Beth A. , Fox Mary A. , McGready John , Yager James P. , Burke Thomas A.
Published: July 2011

Objectives. We evaluated the relationship between local food protection capacity and service provision in Maryland's 24 local food protection programs (FPPs) and incidence of foodborne illness at the county level.

Methods. We conducted regression analyses to determine the relationship between foodborne illness and local FPP characteristics. We used the Centers for Disease Control and Prevention's FoodNet and Maryland Department of Health and Mental Hygiene outbreak data set, along with data on Maryland's local FPP capacity (workforce size and experience levels, budget) and service provision (food service facility inspections, public notification programs).

Results. Counties with higher capacity, such as larger workforce, higher budget, and greater employee experience, had fewer foodborne illnesses. Counties with better performance and county-level regulations, such as high food service facility inspection rates and requiring certified food manager programs, respectively, had lower rates of illness.

Conclusions. Counties with strong local food protection capacity and services can protect the public from foodborne illness. Research on public health services can enhance our understanding of the food protection infrastructure, and the effectiveness of food protection programs in preventing foodborne illness.
Anatomical and Physiological Characteristics Associated with Corn Endosperm Texture
Authors: Zhang Haiyan , Gao Rongqi , Dong Shuting
Published: July 2011

Grain texture is an important trait in corn (Zea mays L.) grain quality, influencing grain shipping and processing characteristics, susceptibility to insects, and flour cooking properties. The objective of this study was to evaluate anatomical and physiological factors affecting corn grain texture for three corn types differing in endosperm texture (Dent corn with floury‐textured endosperm, and popcorn and sweet corn with vitreous‐textured endosperm). The endosperm cell number and size, diameter of starch granules and the distribution of starch granules and protein bodies during grain development were determined. The levels of protein, starch and soluble sugar, and the arrangement of starch granule in mature grains were evaluated. There were significant genotypic differences (P < 0.05), but no significant year effects (P > 0.05) on any of those parameters. At mature stage, a genotype × year interaction was detected only for protein content. The percentage of vitreous endosperm ranged from 39 to 100% in 2004 and from 41 to 100% in 2005. Grain texture was positively associated with the levels of protein (r = 0.684, P ≤ 0.134) and soluble sugar (r = 0.992, P ≤ 0.0001), and negatively associated with starch level (r = –0.627, P ≤ 0.182), endosperm cell number (r = –0.814, P ≤ 0.049), endosperm cell length (r = –0.971, P ≤ 0.001) and width (r = –0.967, P ≤ 0.002), starch granule diameter (r = –0.868, P ≤ 0.025). Our results indicated that the vitreous texture of corn grains was associated with the presence of sugar‐starch compound, protein bodies and proteinaceous matrix, and well‐organized starch granules in the endosperm.
Remote Sensing Leaf Chlorophyll Content Using a Visible Band Index
Authors: Hunt E. Raymond , Daughtry C. S. T. , Eitel Jan U. H. , Long Dan S.
Published: July 2011

Leaf chlorophyll content (μg cm−2) is an important variable for agricultural remote sensing because of its close relationship to leaf N content. The objectives of this study were to develop and test a new index, based on red, green and blue bands, that is sensitive to differences in leaf chlorophyll content at leaf and canopy scales. We propose the triangular greenness index (TGI), which calculates the area of a triangle with vertices: (λr, Rr), (λg, Rg), and (λb, Rb), where λ is the wavelength (nm) and R is the reflectance for bands in red (r), green (g), and blue (b) wavelengths. The TGI was correlated with chlorophyll content using a variety of leaf and plot reflectance data. Generally, indices using the chlorophyll red‐edge (710–730 nm) had higher correlations with chlorophyll content compared to TGI. However, correlations between TGI and chlorophyll content were equal to or higher than broad‐band indices, when leaf area index (LAI) was >2. Simulations using the Scattering by Arbitrarily Inclined Leaves (SAIL) canopy model indicate an interaction among TGI, LAI, and soil type at low LAI, whereas at high LAI, TGI was only affected by leaf chlorophyll content. The TGI could be used with low‐cost sensors, such as commercially‐available digital cameras, for N management by remote sensing.
Crop Model Calibration: A Statistical Perspective
Authors: Wallach Daniel
Published: July 2011

It is common practice to calibrate crop models. This involves estimating some of the model parameters to give a better fit of the model to data. The purpose of this study was to investigate the statistical treatment of crop model calibration, which has not previously been done and is important to better understand the properties of the calibrated model. We considered the case where there is only a single type of variable measured, in the limit of a very large amount of data, and where estimation is based on least squares. We supposed that the individual process models that make up a crop model are such that, for the true parameter values, model error has expectation zero and is independent of the explanatory variables. We show that even in this case, the crop model does not have these properties (i.e., it is misspecified). Based on the structure of crop models and a simulation study, we argue that misspecification is often quite important for crop models. Under misspecification, calibration still tends to minimize prediction error but only for the variable and sampled population used for calibration. There is no assurance that calibration improves prediction for other variables or other populations.
Spatial Modeling of Critical Planting Date for Winter Rye Cover Crop to Enhance Nutrient Recovery
Authors: Farsad Ali , Randhir Timothy O. , Herbert Stephen J. , Hashemi Masoud
Published: July 2011

Time of planting plays a critical role in nutrient recovery from soils by a winter rye (Secale cereale L.) cover crop. A delay in planting can significantly decrease cover crop performance. This study evaluated cover crop planting dates for different areas of Massachusetts using a spatial model based on growing degree days. Field studies were conducted during 2004 through 2009 to estimate biomass production and nutrient recovery of rye under various planting dates from mid‐August to early October. A spatial model identified the critical planting date (CPD) for all locations in Massachusetts based on field studies combined with long‐term weather data collected from 14 weather stations. In eastern areas of Massachusetts (Zone 5), CPD is the third week of September. In this region, there is adequate time for planting winter rye after corn (Zea mays L.) is harvested. Critical planting dates for central parts of the state (Zones 3 and 4) are from the first to second weeks of September. Growers in these regions should consider alternative management strategies including selection of shorter season corn hybrids to meet the suggested cover crop planting dates. The suggested critical planting dates (third–fourth week of August) for northwest regions of Massachusetts (Zones 1 and 2) may not be practical because corn silage is usually not ready for harvest until mid‐September. The model can be a powerful decision‐making tool for researchers and farmers, not only for winter rye in Massachusetts, but it also can be adapted for use with other cover crop species and for use in other regions where cover crops are grown.