bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Intracavernous Administration of Angiopoietin-4 on Erectile Function in the Streptozotocin-Induced Diabetic Mouse
Authors: Kwon Mi-Hye , Ryu Ji-Kan , Kim Woo Jean , Jin Hai-Rong , Song Kang-Moon , Kwon Ki-Dong , Batbold Dulguun , Yin Guo Nan , Koh Gou Young , Suh Jun-Kyu
Published: August 2013

Introduction

Erectile dysfunction (ED) is a highly prevalent complication of diabetes, and the severity of endothelial dysfunction is one of the most important factors in reduced responsiveness to oral phosphodiesterase type 5 inhibitors.

Aim

To study the effects of human angiopoietin-4 (Ang-4) protein on erectile function in diabetic mice.

Methods

Diabetes was induced by intraperitoneal injection of streptozotocin into 8-week-old C57BL/6J male mice. At 8 weeks after the induction of diabetes, the animals were divided into four groups: control nondiabetic mice and diabetic mice receiving two successive intracavernous injections of phosphate buffered saline (days −3 and 0), a single intracavernous injection of Ang-4 protein (day 0), or two successive intracavernous injections of Ang-4 protein (days −3 and 0).

Main Outcome Measures

One week after treatment, we measured erectile function by electrical stimulation of the cavernous nerve. The penis was harvested and stained with hydroethidine or antibodies to Ang-4, platelet/endothelial cell adhesion molecule-1, and phosphorylated endothelial nitric oxide synthase (eNOS). We also determined the differential expression of Ang-4 in cavernous tissue in the control and diabetic mice. The effect of Ang-4 protein on the phosphorylation of Tie-2, Akt, and eNOS was determined in human umbilical vein endothelial cells (HUVECs) by Western blot.

Results

The cavernous expression of Ang-4 was downregulated in diabetic mice; Ang-4 was mainly expressed in endothelial cells. Local delivery of Ang-4 protein significantly increased cavernous endothelial content, induced eNOS phosphorylation, and decreased the generation of superoxide anion and apoptosis in diabetic mice. Ang-4 protein strongly increased the phosphorylation of Tie-2, Akt, and eNOS in HUVECs. Repeated intracavernous injections of Ang-4 induced significant restoration of erectile function in diabetic mice (87% of control values), whereas a single intracavernous injection of Ang-4 protein elicited modest improvement.

Conclusions

Cavernous endothelial regeneration by use of Ang-4 protein may have potential for the treatment of vascular disease-induced ED, such as diabetic ED.
Prediction of morbidity and mortality in patients with chronic hepatitis C by non‐invasive liver fibrosis models
Authors: Chinnaratha Mohamed A. , Jeffrey Gary P. , MacQuillan Gerry , Rossi Enrico , de Boer Bastiaan W. , Speers David J. , Adams Leon A.
Published: August 2013

Background & Aims

Liver fibrosis is prognostic of outcomes among patients with chronic hepatitis C (CHC). We evaluated the accuracy of non‐invasive markers and liver biopsy in predicting morbidity and mortality in CHC patients.

Methods

Compensated CHC patients were evaluated over a 10‐year period. Non‐invasive markers including Hepascore, FIB‐4, APRI and liver biopsy results were retrospectively collated. Follow‐up morbidity and mortality data were obtained from the Western Australian Data Linkage System. The prognostic significance of baseline non‐invasive markers and biopsy were assessed using Kaplan–Meier analysis.

Results

A total of 406 subjects (64% male, mean age 48 ± 11 years) were followed up for 2385 person‐years, during which there were 22 (5.4%) deaths including 14 (3.4%) who died from liver disease or required liver transplantation. Sixteen (3.9%) subjects developed liver decompensation. Hepascore and liver biopsy (P < 0.005) but not APRI or FIB‐4 were predictive of overall and liver‐related mortality as well as liver decompensation. A Hepascore>0.5 was associated with increased overall mortality [Hazard Ratio (95%CI) 6.7 (2.6–17), P < 0.001], liver‐related mortality [32.8 (4.3–250), P = 0.001] and risk of future decompensation [11.8 (3.3–41), P < 0.001], whereas a Hepascore ≤0.5 was associated with a 99% probability of not dying from liver‐related causes over 10 years. Hepascore had comparable accuracy with liver biopsy in predicting liver‐related mortality with AUROC of 0.86 (95%CI 0.80–0.90) and 0.87 (0.79–0.96), respectively.

Conclusion

Hepascore is predictive of overall and liver‐related mortality and morbidity in CHC patients with comparable accuracy to liver biopsy. Hepascore may be a useful prognostic marker in clinical practice.
Vertical zonation and aggregated distribution of the Manila clam on subtidal sand flats in a coastal brackish lagoon along the Sea of Japan
Authors: Yamada Katsumasa , Miyamoto Yasushi , Fujii Chisato , Yamaguchi Keiko , Hamaguchi Masami
Published: August 2013

The Manila clam, Ruditapes philippinarum, has maintained small‐sized populations in a semi‐enclosed brackish lake along the Sea of Japan, the Honjo area of Lake Nakaumi, although the environment and biota of this area have changed dramatically due to a large‐scale reclamation project. There should be underlying processes that enable the restoration of this species from small‐sized populations, such as the existence of source (i.e. reproductive) populations in other areas and depth zones of the lake. However, there has been no robust, properly designed evaluation of the distribution of the Manila clam in the subtidal sand flats. In order to elucidate the possible mechanisms that allow for the persistence of populations of the Manila clam, we examined the spatiotemporal and vertical variation in distributions of 0‐age clams in the subtidal zone of sand flats. Seasonal effects on population variations showed erratic changes among depth zones without a decreasing trend along the depth gradient. Further, many local populations became extinct even in the shallower zones due to seasonal (summer) hypoxia at deeper zones and hypoxia by the accumulation of key benthic species (Asian mussel and decaying macroalgae) in mats at shallower zones. A few surviving local populations were stable with a spatial‐fragmental (patchy) distribution, associated with fragmented accumulations of Asian mussels and macroalgae. Efforts to maintain stable populations and to restore this species in the subtidal area may depend on these small, restricted, patchy local populations. These findings suggest that high fertility and productivity of the Manila clam as well as patchy distribution of small populations may contribute to the maintenance of the population and the avoidance of extinction (by spatially diffusing the risk of extinction) in harsh environments resulting from the reclamation project.
Three‐dimensional microstructure of samples recovered from asteroid 25143 Itokawa: Comparison with LL5 and LL6 chondrite particles
Authors: Tsuchiyama Akira , Uesugi Masayuki , Uesugi Kentaro , Nakano Tsukasa , Noguchi Ryo , Matsumoto Toru , Matsuno Junya , Nagano Takashi , Imai Yuta , Shimada Akira , Takeuchi Akihisa , Suzuki Yoshio , Nakamura Tomoki , Noguchi Takaaki , Abe Masanao , Yada Toru , Fujimura Akio
Published: August 2013

In this study, the three‐dimensional (3‐D) microstructure of 48 Itokawa regolith particles was examined by synchrotron microtomography at SPring‐8 during the preliminary examination of Hayabusa samples. Moreover, the 3‐D microstructure of particles collected from two LL6 chondrites (Ensisheim and Kilabo meteorites) and an LL5 chondrite (Tuxtuac meteorite) was investigated by the same method for comparison. The modal abundances of minerals, especially olivine, bulk density, porosity, and grain size are similar in all samples, including voids and cracks. These results show that the Itokawa particles, which are surface materials from the S‐type asteroid Itokawa, are consistent with the LL chondrite materials in terms of not only elemental and isotopic composition of the minerals but also 3‐D microstructure. However, we could not determine whether the Itokawa particles are purely LL5, LL6, or a mixture of the two. No difference between the particles collected from Rooms A and B of the sample chamber, corresponding to the sampling sequence of the spacecraft's second and first touchdowns, respectively, was detected because of the statistically small amount of particles from Room B.
First evidence of cryptic species diversity and significant population structure in a widespread freshwater nematode morphospecies (Tobrilus gracilis)
Authors: Ristau Kai , Steinfartz Sebastian , Traunspurger Walter
Published: August 2013

Free‐living nematodes are ubiquitous and highly abundant in terrestrial and aquatic environments, where they sustain ecosystem functioning by mineralization processes and nutrient cycling. Nevertheless, very little is known about their true diversity and intraspecific population structure. Recent molecular studies on marine nematodes indicated cryptic diversity and strong genetic differentiation of distinct populations, but for freshwater nematode species, analogous studies are lacking. Here, we present the first extensive molecular study exploring cryptic species diversity and genetic population structure of a widespread freshwater nematode morphospecies, Tobrilus gracilis, from nine postglacially formed European lakes. Taxonomic species status of individuals, analysed for fragments of the mitochondrial COI gene and for the large (LSU) and small (SSU) ribosomal subunits, were determined by morphological characteristics. Mitochondrial and nuclear markers strongly supported the existence of three distinct genetic lineages (Tg I–III) within Tobrilus gracilis, suggesting that this morphospecies indeed represents a complex of highly differentiated biological species. High genetic diversity was also observed at the population level. Across the nine lakes, 19 mitochondrial, and seven (LSU) and four (SSU) nuclear haplotypes were determined. A phylogeographical analysis revealed remarkable genetic differentiation even among neighbouring lake populations for one cryptic lineage. Priority and persistent founder effects are possible explanations for the observed population structure in the postglacially colonized lakes, but ask for future studies providing direct estimates of freshwater nematode dispersal rates. Our study suggests therefore that overall diversity of limnetic nematodes has been so far drastically underestimated and challenges the assumed ubiquitous distribution of other, single freshwater nematode morphospecies.
High connectivity across the fragmented chemosynthetic ecosystems of the deepAtlanticEquatorialBelt: efficient dispersal mechanisms or questionable endemism?
Authors: Teixeira Sara , Olu Karine , Decker Carole , Cunha Regina L. , Fuchs Sandra , Hourdez Stéphane , Serrão Ester A. , Arnaud‐Haond Sophie
Published: August 2013

Chemosynthetic ecosystems are distributed worldwide in fragmented habitats harbouring seemingly highly specialized communities. Yet, shared taxa have been reported from highly distant chemosynthetic communities. These habitats are distributed in distinct biogeographical regions, one of these being the so‐calledAtlanticEquatorialBelt (AEB). Here, we combined genetic data (COI) from several taxa to assess the possible existence of cryptic or synonymous species and to detect the possible occurrence of contemporary gene flow among populations of chemosynthetic species located on both sides of theAtlantic. SeveralEvolutionarySignificantUnits (ESUs) of Alvinocarididae shrimp andVesicomyidae bivalves were found to be shared across seeps of theAEB. Some were also common to hydrothermal vent communities of theMid‐AtlanticRidge (MAR), encompassing taxa morphologically described as distinct species or even genera. The hypothesis of current or very recent large‐scale gene flow among seeps and vents was supported by microsatellite analysis of the shrimp speciesAlvinocaris muricola/Alvinocaris markensisacross theAEBandMAR. Two nonmutually exclusive hypotheses may explain these findings. The dispersion of larvae or adults following strong deep‐sea currents, possibly combined with biochemical cues influencing the duration of larval development and timing of metamorphosis, may result in large‐scale effective migration among distant spots scattered on the oceanic seafloor. Alternatively, these results may arise from the prevailing lack of knowledge on the ocean seabed, apart from emblematic ecosystems (chemosynthetic ecosystems, coral reefs or seamounts), where the widespread classification of endemism associated with many chemosynthetic taxa might hide wider distributions in overlooked parts of the deep sea.
Dynamic Planning of Facility Locations with Benefits from Multitype Facility Colocation
Authors: Xie Weijun , Ouyang Yanfeng
Published: August 2013

This article presents a mixed‐integer programming model for a multitype facility colocation problem with capacity expansion over a multiperiod horizon. This problem is motivated by the emerging U.S. biofuel industry that is rapidly expanding its infrastructure facilities to produce bioethanol from agricultural crops. Each type of facility (e.g., corn‐ or cellulose‐based biorefinery) requires a different type of raw material (e.g., corn or perennial grass), but they produce the same final product (e.g., bioethanol), and colocation of multiple types of facilities results in cost‐saving benefits due to complementary production process and byproduct recycling. Multiple solution approaches (i.e., Lagrangian relaxation, Benders decomposition, and accelerated Benders decomposition) are proposed to solve this problem. Numerical experiments show that accelerated Benders decomposition most effectively solves large‐sized problems in a short amount of time. Various managerial insights are also drawn from the computational results.
MATHEMATICAL STUDY OF A PEST CONTROL MODEL INCORPORATING STERILE INSECT TECHNIQUE
Authors: BHATTACHARYYA R. , MUKHOPADHYAY B.
Published: August 2013

The menace of insect pests is a topic of major concern throughout the world. Chemical pesticides are conventionally used to control these insect pests. However, the adverse effects of these synthetic pesticides, such as high toxicity from residues in food, contamination of water and the environment resulting in human health hazard and resistance of the pest to the pesticides have necessitated development of some nonconventional approaches of biological pest control.

In this research, we have focused on a mathematical model of biological pest control using the sterile insect release technique. Unlike most of the existing modeling studies in this field that mainly deal with the pest population only, we have incorporated the crop population as a distinct dynamical equation together with the fertile and sterile insect pests. Local stability analysis is performed around the crop and fertile insect free axial equilibrium, the fertile‐insect‐free boundary equilibrium, the crop‐free boundary equilibrium and the equilibrium point of coexistence. From the study we have derived a number of thresholds for the SIRR (the main parameter for our study) that cause existence and or extinction of the crop population as well as the fertile insect pests. A global study of the model system using comparison arguments revealed existence of a global attractor for the system. Numerical simulations are done to support and augment analytical results.
THE DYNAMICS OF AN ANIMAL—VEGETATION SYSTEM: SHEEP FARMING
Authors: DA ROCHA JOSÉ‐MARÍA , SKONHOFT ANDERS
Published: August 2013

The paper studies the economy and ecology of sheep farming at the farm level in a Nordic context, with a crucial distinction between the outdoors grazing season and the winter indoors feeding season, and where climate conditions fix the length of the grazing season. Two different categories of animals, ewes (adult females) and lambs, and one plant species are included in our ecological model. The farmer is assumed to maximize present‐value profit where the revenue is made up income from meat and wool production. We find that livestock cycles may represent an optimal management policy. We also show that in a possible steady state with a constant number of animals and constant vegetation quantity, slaughtering either only lambs or only ewes is optimal.
Pure Closed Posteromedial Dislocation of the Tibiotalar Joint without Fracture
Authors: Wang Yun‐tao , Wu Xiao‐tao , Chen Hui
Published: August 2013

Pure tibiotalar dislocation without an associated fracture is an extremely rare injury. We present three cases of closed posteromedial tibiotalar dislocation without any associated fractures to the foot, ankle, or leg. All patients were treated conservatively with immediate closed reduction under general or local anaesthesia and immobilised in a short leg cast for six weeks without weight‐bearing resulting in a satisfactory outcome at the final follow‐up. A review of the literature is also presented in this paper.
An Efficacy Analysis of Surgical Timing and Procedures for High‐Energy Complex Tibial Plateau Fractures
Authors: Xu Yun‐qin , Li Qiang , Shen Tu‐gang , Su Pei‐hua , Zhu Ya‐zhong
Published: August 2013

Objective

To identify the most effective treatment for application to high‐energy complex plateau fractures.

Methods

125 patients with closed high‐energy complex tibial plateau fractures who had been surgically treated between 2003 and 2010 were reviewed retrospectively. Five procedure methods were studied (e.g. four open reduction and internal fixations, and close reduction via a minimal incision with hybrid external fixation) in five surgical timings, with a control group. The incidence of wound complications after operative treatment in the five surgical timings and the clinical effects of the five surgical procedure options were evaluated statistically. A postoperative follow‐up ranging 26–110 months (mean, 36.5 months) was performed.

Results

Among the various groups, the respective overall wound complication incidences were 20.0%, 41.6%, 33.3%, 2.5%, and 16.7% within 4 hours, 4 hours to 3 days, 3–5 days, 5–8 days, and more than 8 days after injury. Failed fixation was clearly observed in Group 1 (23.1%, 6/26) and Group 5 (21.7%, 5/23) (P < 0.05). Significant differences were also found among Group 2 (92.6%), Group 3 (93.3%), and Group 5 (69.6%), in terms of the good and excellent rate of joint function according to the Rasmussen score (P < 0.05).

Conclusion

The optimal surgical timing is within 4 hours after trauma, for which no obvious swelling was observed in the limbs. This is followed by surgical timing within 5–8 days, after which trauma showed only subsided limb swelling. Dual plating provides the best stabilization option, as it allows early joint mobilization, cartilage regeneration, and joint remodeling, thus decreasing the risk of joint stiffness. Hybrid external fixation may provide relative stability to maintain fracture alignment without the need for massive soft tissue dissection, and also minimizes blood loss and potential soft tissue complications.
Re‐conceptualising Prenatal Life Stressors in Predicting Post‐partum Depression: Cumulative‐, Specific‐, and Domain‐specific Approaches to Calculating Risk
Authors: Liu Cindy H. , Tronick Ed
Published: August 2013

Background

Prenatal life stress predicts post‐partum depression (PPD); however, studies generally examine individual stressors (a specific approach) or the summation of such exposure (a cumulative approach) and their associations with PPD. Such approaches may oversimplify prenatal life stress as a risk factor for PPD. We evaluated approaches in assessing prenatal life stress as a predictor of PPD diagnosis, including a domain‐specific approach that captures cumulative life stress while accounting for stress across different life stress domains: financial, relational, and physical health.

Methods

The Pregnancy Risk Assessment Monitoring System, a population‐based survey, was used to analyse the association of prenatal life stressors with PPD diagnoses among 3566 New York City post‐partum women.

Results

Specific stressors were not associated with PPD diagnosis after controlling for sociodemographic variables. Exposure to a greater number of stressors was associated with PPD diagnosis, even after adjusting for both sociodemographic variables and specific stressors [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.5, 6.7]. Individuals reporting a moderate‐to‐high number of financial problems along with a moderate‐to‐high number of physical problems were at greater odds of PPD (OR = 4.2, 95% CI = 1.2, 15.3); those with a moderate‐to‐high number of problems in all three domains were at over fivefold increased odds of PPD (OR = 5.5, CI = 1.1, 28.5).

Conclusions

In assessing prenatal stress, clinicians should consider the extent to which stressors occur across different life domains; this association appears stronger with PPD diagnosis than simple assessments of individual stressors, which typically overestimate risk or cumulative exposures.
Role of the epithelial cell rests of Malassez in the development, maintenance and regeneration of periodontal ligament tissues
Authors: Xiong Jimin , Gronthos Stan , Bartold P. Mark
Published: August 2013

Periodontitis is a highly prevalent inflammatory disease that results in damage to the tooth‐supporting tissues, potentially leading to tooth loss. Periodontal tissue regeneration is a complex process that involves the collaboration of two hard tissues (cementum and alveolar bone) and two soft tissues (gingiva and periodontal ligament). To date, no periodontal‐regenerative procedures provide predictable clinical outcomes. To understand the rational basis of regenerative procedures, a better understanding of the events associated with the formation of periodontal components will help to establish reliable strategies for clinical practice. An important aspect of this is the role of the Hertwig's epithelial root sheath in periodontal development and that of its descendants, the epithelial cell rests of Malassez, in the maintenance of the periodontium. An important structure during tooth root development, the Hertwig's epithelial root sheath is not only a barrier between the dental follicle and dental papilla cells but is also involved in determining the shape, size and number of roots and in the development of dentin and cementum, and may act as a source of mesenchymal progenitor cells for cementoblasts. In adulthood, the epithelial cell rests of Malassez are the only odontogenic epithelial population in the periodontal ligament. Although there is no general agreement on the functions of the epithelial cell rests of Malassez, accumulating evidence suggests that the putative roles of the epithelial cell rests of Malassez in adult periodontal ligament include maintaining periodontal ligament homeostasis to prevent ankylosis and maintain periodontal ligament space, to prevent root resorption, to serve as a target during periodontal ligament innervation and to contribute to cementum repair. Recently, ovine epithelial cell rests of Malassez cells have been shown to harbor clonogenic epithelial stem‐cell populations that demonstrate similar properties to mesenchymal stromal/stem cells, both functionally and phenotypically. Therefore, the epithelial cell rests of Malassez, rather than being ‘cell rests’, as indicated by their name, are an important source of stem cells that might play a pivotal role in periodontal regeneration.
Neutrophil extracellular traps as a new paradigm in innate immunity: friend or foe?
Authors: Cooper Paul R. , Palmer Lisa J. , Chapple Iain L. C.
Published: August 2013

The discovery of neutrophil extracellular traps in 2004 opened a fascinating new chapter in immune‐mediated microbial killing. Brinkman et al. demonstrated that neutrophils, when catastrophically stimulated, undergo a novel form of programmed cell death (neutrophil extracellular trap formation) whereby they decondense their entire nuclear chromatin/DNA and release the resulting structure into the cytoplasm to mix with granule‐derived antimicrobial peptides before extruding these web‐like structures into the extracellular environment. The process requires the activation of the granule enzyme peptidyl arginine deiminase‐4, the formation of reactive oxygen species (in particular hypochlorous acid), the neutrophil microtubular system and the actin cytoskeleton. Recent work by Yousefi et al. demonstrated that exposure to different agents for shorter stimulation periods resulted in neutrophil extracellular trap release from viable granulocytes, and that such neutrophil extracellular traps comprised mitochondrial DNA rather than nuclear DNA and were also capable of microbial entrapment and destruction. Deficiency in NADPH‐oxidase production (as found in patients with chronic granulomatous disease) results in an inability to produce neutrophil extracellular traps and, along with their failure to produce antimicrobial reactive oxygen species, these patients suffer from severe, and sometimes life‐threatening, infections. However, conversely the release of nuclear chromatin into tissues is also potentially autoimmunogenic and is now associated with the generation of anti‐citrullinated protein antibodies in seropositive rheumatoid arthritis. Other neutrophil‐derived nuclear and cytoplasmic contents are also pathogenic, either through direct effects on tissues or via autoimmune processes (e.g. autoimmune vasculitis). In this review, we discuss the plant origins of a highly conserved innate immune method of microbial killing, the history and biology of neutrophil extracellular traps and their role in defence and in human diseases. We attempt to resolve areas of controversy and propose roles for excess neutrophil extracellular trap release from hyperactive/reactive neutrophils and for the unique peptidyl arginine deiminase enzyme of Porphyromonas gingivalis in the pathogenesis of periodontitis, and subsequently a role for periodontitis/the peptidyl arginine deiminase enzyme of P. gingivalis in the causal pathway of autoimmune diseases such as rheumatoid arthritis. We propose that neutrophil extracellular trap and peptidyl arginine deiminase release may propagate tissue‐destructive mechanisms rather than provide protection in susceptible individuals and that release of host‐derived DNase may play an important role in the digestion and removal of neutrophil extracellular traps within tissues.
Defensins and LL‐37: a review of function in the gingival epithelium
Authors: Greer Ara , Zenobia Camille , Darveau Richard P.
Published: August 2013

Antimicrobial peptides represent an important aspect of the innate defense system that contributes to the control of bacterial colonization and infection. As studies have progressed it has become clear that antimicrobial peptides manifest other functions in addition to their antimicrobial effects. These functions include chemotaxis of numerous types of host cells involved in both the innate and adaptive immune responses. In this review, the antimicrobial activity, the regulation and the contribution to host homeostasis of alpha‐defensins and LL‐37, as well as of beta‐defensins, are discussed in the context of their specific tissue locations in the junctional epithelium and oral epithelium, respectively.
Macrophage subsets and osteoimmunology: tuning of the immunological recognition and effector systems that maintain alveolar bone
Authors: Sima Corneliu , Glogauer Michael
Published: August 2013

Chronic and aggressive periodontal diseases are characterized by the failure to resolve local inflammation against periodontopathogenic bacteria in the subgingival biofilm. Alveolar bone resorption is associated with altered innate and adaptive immune responses to periodontal pathogens. Macrophage‐derived cytokines, chemokines and growth factors, present in both destructive and reparative phases of periodontitis, are elevated in numerous animal and human studies. Macrophage polarization to either a predominantly pro‐inflammatory or anti‐inflammatory phenotype may be a critical target for monitoring disease activity, modulating immune responses to subgingival biofilms in patients at risk and reducing alveolar bone loss.
Building a Conceptual Approach to Collective Learning: Lessons for Public Policy Scholars
Authors: Heikkila Tanya , Gerlak Andrea K.
Published: August 2013

In public policy processes, collective learning among policy actors is important in shaping how these processes unfold and the types of policy outcomes that may result. Despite a widespread interest in learning by policy scholars, researchers face a number of conceptual and theoretical challenges in studying learning across different collective settings within policy processes. In this article, we offer a theoretically grounded approach to defining and understanding collective‐level learning. In defining learning, we first draw out the connection between learning processes and learning products, both cognitive and behavioral. In examining learning processes, we further explore the relationship between individual and collective learning. Then we identify and define the key characteristics of collective settings that will likely influence learning processes. We conclude by offering recommendations for policy scholars to apply this approach in studies of learning across diverse policy contexts.
Cost Control after the ACA
Authors: White Joseph
Published: August 2013

This Perspective explains why implementation analysis of the cost control provisions within the Patient Protection and Affordable Care Act is not particularly useful. These provisions are either relatively straightforward or, more commonly, so flawed that successful implementation is highly unlikely. The analysis shows that effective and equitable cost control will require coordinating payers to create all‐payer fee setting. This poses significant challenges but has been implemented relatively successfully in many countries. The balance of the article uses experience with all‐payer systems in other countries and fee setting within Medicare to identify key choices within any all‐payer system. It highlights the importance of simplifying considerations and focusing on outcomes—the incomes of providers and total spending—rather than engaging in a hopeless search for technocratic payment “accuracy.”
Effect of Different Levels of Glycerol and Cholesterol‐Loaded Cyclodextrin on Cryosurvival of Ram Spermatozoa
Authors: Motamedi‐Mojdehi R , Roostaei‐Ali Mehr M , Rajabi‐Toustani R
Published: August 2013

Contents

This study was conducted to determine the optimum level of glycerol and cholesterol‐loaded cyclodextrin (CLC) in a Tris‐based diluent for cryopreservation of ram spermatozoa.Ram semen was treated with 0, 1.5, 3 or 4.5 mgCLC/120 × 106 cells inTris‐based diluents containing 3, 5 or 7% glycerol in a factorial arrangement 3 × 4 and frozen in liquid nitrogen vapour. Sperm motility, viability (eosin–nigrosin staining) and functional membrane integrity (hypo‐osmotic swelling test) were assessed immediately after thawing (0 h) and subsequently after 3 and 6 h at 37°C. There was an interaction betweenCLCand glycerol on the functional membrane integrity (p < 0.05). In the presence of 3% glycerol, the highest functional membrane integrity (32.2%) was found in the spermatozoa treated with 1.5 mgCLC/120 × 106 sperm. Post‐thaw sperm motility was highest in 1.5 mgCLCimmediately after thawing (40.5%) and after 3‐h (30.6%) incubation at 37°C (p < 0.05). Viability of spermatozoa was higher in allCLCtreatments than in the untreated samples, and it was highest (33.9%) in the spermatozoa treated with 1.5 mgCLC(p < 0.05). These data indicate that the addition of cholesterol to sperm membranes by 1.5 mgCLC/120 × 106 cells may allow the use of a lower concentration of glycerol (3%), which is sufficient to mitigate the detrimental effects of freezing and thawing.
Restoring Tropical Dry Forest Communities: Effects of Habitat Management and Outplantings on Composition and Structure
Authors: Brooks Wesley R. , Jordan Rebecca C.
Published: August 2013

We sought to increase the conservation value and ecological resilience of a disturbed woodlot on protected land in suburban Miami‐Dade County, Florida, by restoring a local tropical dry forest community. These efforts included adding 26 “novel native” tropical hardwood hammock species in different SR and density treatments, and conducting regular habitat management actions including exotic biomass removal. We monitored a variety of community composition and forest structure variables over 2 years to assess the success of our restoration efforts and the relative roles of habitat management versus native outplantings in achieving those outcomes. Habitat management proved influential to changing forest structure, while both habitat management and outplantings impacted changes in community composition, at least in the short term. Habitat management and outplantings in combination, however, allowed us to successfully (1) increase the number of native species and decrease the number of exotic species, (2) increase the number of protected plant species on the site, and (3) alter the community composition and forest structure of the site from that of a highly disturbed woodlot to that of a typical Miami Rock Ridge tropical hardwood hammock. Our success in meeting these restoration goals in just 2 years is one such example where simple native outplanting and exotic control projects can produce large returns with minimal resources in the form of time, money, and manpower. Finally, restoring regrowth sites or other remnant habitats may prove an efficient and effective way to conserve biodiversity and basic ecosystem processes in close proximity to metropolitan areas.
Multiple-Membership Multiple-Classification Models for Social Network and Group Dependences
Authors: Tranmer Mark , Steel David , Browne William J.
Published: August 2013

The social network literature on network dependences has largely ignored other sources of dependence, such as the school that a student attends, or the area in which an individual lives. The multilevel modelling literature on school and area dependences has, in turn, largely ignored social networks. To bridge this divide, a multiple-membership multiple-classification modelling approach for jointly investigating social network and group dependences is presented. This allows social network and group dependences on individual responses to be investigated and compared. The approach is used to analyse a subsample of the Adolescent Health Study data set from the USA, where the response variable of interest is individual level educational attainment, and the three individual level covariates are sex, ethnic group and age. Individual, network, school and area dependences are accounted for in the analysis. The network dependences can be accounted for by including the network as a classification in the model, using various network configurations, such as ego-nets and cliques. The results suggest that ignoring the network affects the estimates of variation for the classifications that are included in the random part of the model (school, area and individual), as well as having some influence on the point estimates and standard errors of the estimates of regression coefficients for covariates in the fixed part of the model. From a substantive perspective, this approach provides a flexible and practical way of investigating variation in an individual level response due to social network dependences, and estimating the share of variation of an individual response for network, school and area classifications.
Large Covariance Estimation by Thresholding Principal Orthogonal Complements
Authors: Fan Jianqing , Liao Yuan , Mincheva Martina
Published: August 2013

The paper deals with the estimation of a high dimensional covariance with a conditional sparsity structure and fast diverging eigenvalues. By assuming a sparse error covariance matrix in an approximate factor model, we allow for the presence of some cross-sectional correlation even after taking out common but unobservable factors. We introduce the principal orthogonal complement thresholding method ‘POET’ to explore such an approximate factor structure with sparsity. The POET-estimator includes the sample covariance matrix, the factor-based covariance matrix, the thresholding estimator and the adaptive thresholding estimator as specific examples. We provide mathematical insights when the factor analysis is approximately the same as the principal component analysis for high dimensional data. The rates of convergence of the sparse residual covariance matrix and the conditional sparse covariance matrix are studied under various norms. It is shown that the effect of estimating the unknown factors vanishes as the dimensionality increases. The uniform rates of convergence for the unobserved factors and their factor loadings are derived. The asymptotic results are also verified by extensive simulation studies. Finally, a real data application on portfolio allocation is presented.
Two-Sample Test of High Dimensional Means Under Dependence
Authors: Tony Cai T. , Liu Weidong , Xia Yin
Published: August 2013

The paper considers in the high dimensional setting a canonical testing problem in multivariate analysis, namely testing the equality of two mean vectors. We introduce a new test statistic that is based on a linear transformation of the data by the precision matrix which incorporates the correlations between the variables. The limiting null distribution of the test statistic and the power of the test are analysed. It is shown that the test is particularly powerful against sparse alternatives and enjoys certain optimality. A simulation study is carried out to examine the numerical performance of the test and to compare it with other tests given in the literature. The results show that the test proposed significantly outperforms those tests in a range of settings.
Canine pyoderma gangrenosum: a case series of two dogs
Authors: Simpson Deborah L. , Burton Gregory G. , Hambrook Lydia E.
Published: August 2013

Background

Pyoderma gangrenosum (PG) is a rare disease, which, to the best of the authors' knowledge, has been the subject of only one case report in the peer‐reviewed veterinary literature.

Hypothesis/Objectives

To describe the history, clinical signs, diagnostic findings and treatment outcome in two cases of canine PG.

Animals

Two client‐owned dogs presented to a private veterinary referral practice between 2008 and 2010 who received a diagnosis of PG by specialist veterinary dermatologists.

Methods

Medical records were analysed to retrieve relevant information.

Results

Both dogs were treated with prednisolone; this was combined with ciclosporin in case 1 and azathioprine in case 2. Case 2 had a more complete response of lesions to treatment and a longer survival time after diagnosis (763 days) than case 1 (81 days).

Conclusions and clinical importance

Pyoderma gangrenosum is a rare disease distinguished by rapid progression of painful, necrolytic, cutaneous ulcers with irregular, violaceous undermined borders. Azathioprine with glucocorticoids may lead to a better outcome than ciclosporin and glucocorticoids (currently the first‐line treatment in humans and the only reported treatment in dogs).
Factors influencing selection of drinking water technologies for urban informal settlements in Kampala
Authors: Isoke Jennifer , van Dijk Meine Pieter
Published: August 2013

Access to drinking water in urban informal settlements of developing countries still remains a challenge for the poor and depends on technology selected. This paper determines the score on criteria used for technology selection by two major stakeholders in the water service delivery chain, the users and the utility. The criteria are: affordability to connect, affordability of consumption, method of payment, ease of operation, ease of spare parts acquisition, access distance, access time, generating sufficient water continuously, service coverage, the possibility of cost recovery and security of installation (SOI). The study was carried out in Bwaise II and Kisenyi III, two informal settlements in Kampala, the capital of Uganda. Through a household survey and semistructured interviews of key informants, data were collected for the score on these criteria of four piped water distribution technologies: public water points (PWPs) with conventional meters, PWPs with prepaid meters, house connections and yard taps. Using multicriteria methods and preference elicitation by pair wise ranking, the most preferred factor for technology selection from the users' point of view is affordability to connect, while from the utility's point of view, it is SOI. These preferences were confirmed by data from focus group discussions and in‐depth interviews.
Application of a drainage film reduces fibroblast ingrowth into large‐pored polyurethane foam during negative‐pressure wound therapy in an in vitro model
Authors: Wiegand Cornelia , Springer Steffen , Abel Martin , Wesarg Falko , Ruth Peter , Hipler Uta‐Christina
Published: August 2013

Negative‐pressure wound therapy (NPWT) is an advantageous treatment option in wound management to promote healing and reduce the risk of complications. NPWT is mainly carried out using open‐cell polyurethane (PU) foams that stimulate granulation tissue formation. However, growth of wound bed tissue into foam material, leading to disruption of newly formed tissue upon dressing removal, has been observed. Consequently, it would be of clinical interest to preserve the positive effects of open‐cell PU foams while avoiding cellular ingrowth. The study presented analyzed effects of NPWT using large‐pored PU foam, fine‐pored PU foam, and the combination of large‐pored foam with drainage film on human dermal fibroblasts grown in a collagen matrix. The results showed no difference between the dressings in stimulating cellular migration during NPWT. However, when NPWT was applied using a large‐pored PU foam, the fibroblasts continued to migrate into the dressing. This led to significant breaches in the cell layers upon removal of the samples after vacuum treatment. In contrast, cell migration stopped at the collagen matrix edge when fine‐pored PU foam was used, as well as with the combination of PU foam and drainage film. In conclusion, placing a drainage film between collagen matrix and the large‐pored PU foam dressing reduced the ingrowth of cells into the foam significantly. Moreover, positive effects on cellular migration were not affected, and the effect of the foam on tissue surface roughness in vitro was also reduced.
Experimental Investigation of Vortex Flow in a Two-Chamber Solar Thermochemical Reactor
Authors: Koepf Erik E. , Lindemer Matthew D. , Advani Suresh G. , Prasad Ajay K.
Published: August 2013

Recent advances in the field of large-scale solar thermochemical processing have given rise to substantial research efforts and demonstration projects. Many applications of high-temperature solar-thermal technology employ an enclosed cavity environment, thus requiring a transparent window through which concentrated solar energy can enter. One configuration employed is a two-cavity reactor connected by a narrow aperture, where solar flux entering through the window is focused at the aperture plane before diverging into the lower chamber, where the chemical reaction occurs. For the Zn/ZnO thermochemical cycle where Zn is solar-thermally reduced from ZnO in a high-temperature cavity environment, effective removal of the product gas stream containing zinc vapor is of paramount importance to prevent fouling by condensation on the reactor window. Two argon-jet configurations, tangential and radial, located around the circumference of the upper chamber are used to control the gas flow within the reactor cavity. First, the tangential jets drive a vortex flow, and second, the radial wall jet travels across the window before converging at the reactor center line and turning downward to create a downward jet. The tangential jet-induced flow creates a rotating vortex, contributing to overall flow stability, and the radial jet-induced downward flow counters the updraft created by the vortex while actively cooling and sweeping clear the inner surface of the window. Flow visualization in a full-scale transparent model of the reactor using smoke and laser illumination is employed to characterize the effectiveness of aerodynamic window clearing and to characterize the processes by which a vortex flow develops and breaks down in a two-chamber solar reactor geometry. Based on a large dataset of flow visualization images, a metric is developed to define vortex stability over a wide range of flow conditions and identify an ideal operating range for which a vortex formation path is established that maintains stable flow patterns and removes product gases while minimizing the use of argon gas. The predominant influence of vortex instability and breakdown is identified and examined for the case of a beam-down, two-chamber solar reactor geometry.
The Bauschinger Effect’s Influence on the SIFs of a Semi-Elliptical Crack Emanating From an Erosion at the Bore of a Fully Autofrettaged Pressurized Cylinder
Authors: Ma Q. , Levy C. , Perl M.
Published: August 2013

The benefits of autofrettage for thick-walled cylindrical vessels as a means of improving the vessel’s durability and sustainability have been addressed in the published literature. However the presence of the Bauschinger effect complicates the overall effect of autofrettage, especially when complex three-dimensional crack geometries emanating from erosions at the cylinder bore are considered. In this paper, the Bauschinger effect’s impact on the stress intensity factors (SIFs) on such cracks is investigated. The effect of various erosion geometrical configurations on the mode I stress intensity factor distribution along the front of a semi-elliptical crack, emanating from the deepest line of the erosion surface (DLES) at the bore of an autofrettaged, pressurized thick-walled cylinder of outer-to-inner radius ratio, R0/Ri = 2, is investigated. Both autofrettage with Bauschinger effect (BEDA) and Hill’s ideal autofrettage residual stress field (BEIA) are considered and simulated by an equivalent thermal load. The SIFs are determined for the semi-elliptical cracks of various crack depths to wall thickness ratio, a/t = 0.05 to 0.25, and ellipticities, a/c, ranging from 0.5 to 1.5, emanating from the DLES via ANSYS software and the nodal displacement method. Three groups of erosion geometries are considered: (a) arc erosions of constant relative depth, d/t, equal to 5% and with relative radii of curvature, r′/t, between 5% and 30%; (b) semi-elliptic erosions of constant relative depth, d/t, of 5% with erosion ellipticity, d/h, varying from 0.3 to 2.0; and (c) semi-circular erosions of relative depth, d/t, between 1 and 10% of the wall thickness. KIP, the SIF due to pressurization, is highly dependent on the stress concentration ahead of the DLES which directly relates to the erosion geometry. It is found that the absolute value of KIA, the SIF due to autofrettage, is just slightly reduced by the presence of the erosion. Its change solely depends on, and is directly proportional to, the erosion depth. Thus, the combined SIFs of deep cracks are found to be significantly enhanced by the presence of autofrettage and might result in a shortening of the vessel’s fatigue life by up to an order of magnitude. Counteracting this, the combined SIFs are found to be significantly higher for BEDA cases than for BEIA cases. Therefore the vessel’s fatigue life can be profoundly influenced by the presence of the Bauschinger effect.