4,666 research outputs found
Intrinsic flat stability of the positive mass theorem for graphical hypersurfaces of Euclidean space
The rigidity of the Positive Mass Theorem states that the only complete
asymptotically flat manifold of nonnegative scalar curvature and zero mass is
Euclidean space. We study the stability of this statement for spaces that can
be realized as graphical hypersurfaces in Euclidean space. We prove (under
certain technical hypotheses) that if a sequence of complete asymptotically
flat graphs of nonnegative scalar curvature has mass approaching zero, then the
sequence must converge to Euclidean space in the pointed intrinsic flat sense.
The appendix includes a new Gromov-Hausdorff and intrinsic flat compactness
theorem for sequences of metric spaces with uniform Lipschitz bounds on their
metrics.Comment: 31 pages, 2 figures, v2: to appear in Crelle's Journal, many minor
changes, one new exampl
Prickle1 is required for EMT and migration of zebrafish cranial neural crest
The neural crest—a key innovation of the vertebrates—gives rise to diverse cell types including melanocytes, neurons and glia of the peripheral nervous system, and chondrocytes of the jaw and skull. Proper development of the cephalic region is dependent on the tightly-regulated specification and migration of cranial neural crest cells (NCCs). The core PCP proteins Frizzled and Disheveled have previously been implicated in NCC migration. Here we investigate the functions of the core PCP proteins Prickle1a and Prickle1b in zebrafish cranial NCC development. Using analysis of pk1a and pk1b mutant embryos, we uncover similar roles for both genes in facilitating cranial NCC migration. Disruption of either gene causes pre-migratory NCCs to cluster together at the dorsal aspect of the neural tube, where they adopt aberrant polarity and movement. Critically, in investigating Pk1-deficient cells that fail to migrate ventrolaterally, we have also uncovered roles for pk1a and pk1b in the epithelial-to-mesenchymal transition (EMT) of pre-migratory NCCs that precedes their collective migration to the periphery. Normally, during EMT, pre-migratory NCCs transition from a neuroepithelial to a bleb-based and subsequently, mesenchymal morphology capable of directed migration. When either Pk1a or Pk1b is disrupted, NCCs continue to perform blebbing behaviors characteristic of pre-migratory cells over extended time periods, indicating a block in a key transition during EMT. Although some Pk1-deficient NCCs transition successfully to mesenchymal, migratory morphologies, they fail to separate from neighboring NCCs. Additionally, Pk1b-deficient NCCs show elevated levels of E-Cadherin and reduced levels of N-Cadherin, suggesting that Prickle1 molecules regulate Cadherin levels to ensure the completion of EMT and the commencement of cranial NCC migration. We conclude that Pk1 plays crucial roles in cranial NCCs both during EMT and migration. These roles are dependent on the regulation of E-Cad and N-Cad
Gene Co-expression Network and Copy Number Variation Analyses Identify Transcription Factors Associated With Multiple Myeloma Progression
Multiple myeloma (MM) has two clinical precursor stages of disease: monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). However, the mechanism of progression is not well understood. Because gene co-expression network analysis is a well-known method for discovering new gene functions and regulatory relationships, we utilized this framework to conduct differential co-expression analysis to identify interesting transcription factors (TFs) in two publicly available datasets. We then used copy number variation (CNV) data from a third public dataset to validate these TFs. First, we identified co-expressed gene modules in two publicly available datasets each containing three conditions: normal, MGUS, and SMM. These modules were assessed for condition-specific gene expression, and then enrichment analysis was conducted on condition-specific modules to identify their biological function and upstream TFs. TFs were assessed for differential gene expression between normal and MM precursors, then validated with CNV analysis to identify candidate genes. Functional enrichment analysis reaffirmed known functional categories in MM pathology, the main one relating to immune function. Enrichment analysis revealed a handful of differentially expressed TFs between normal and either MGUS or SMM in gene expression and/or CNV. Overall, we identified four genes of interest (MAX, TCF4, ZNF148, and ZNF281) that aid in our understanding of MM initiation and progression
Modeling Turbidity Currents Using the Multiple-state Discrete-time Markov Chain Approach
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive
Strategic and Operational Benefits of IOS-Enabled Interorganizational Integration
In this study, we employ the lens of the resource-based view of the firm to examine the strategic value of IOS- enabled interorganizational integration. We first develop the key construct of IOS-enabled interorganizational integration, identifying and defining its two dimensions: interorganizational system integration and business integration. Next, we propose that while the two dimensions have positive impacts on operational performance, only interorganizational business integration has strategic value. The data for this study were collected through a survey of firms in mainland China. The results provide empirical support for our propositions. The study contributes to research by providing a clear conceptualization of IOS-enabled interorganizational integration, establishing the theoretical link between its two dimensions and operational and strategic performance, developing scales for interorganizational system integration and business integration, as well as providing data on the IOS experience of Chinese firms
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Spinal cord stimulation in chronic pain: evidence and theory for mechanisms of action.
Well-established in the field of bioelectronic medicine, Spinal Cord Stimulation (SCS) offers an implantable, non-pharmacologic treatment for patients with intractable chronic pain conditions. Chronic pain is a widely heterogenous syndrome with regard to both pathophysiology and the resultant phenotype. Despite advances in our understanding of SCS-mediated antinociception, there still exists limited evidence clarifying the pathways recruited when patterned electric pulses are applied to the epidural space. The rapid clinical implementation of novel SCS methods including burst, high frequency and dorsal root ganglion SCS has provided the clinician with multiple options to treat refractory chronic pain. While compelling evidence for safety and efficacy exists in support of these novel paradigms, our understanding of their mechanisms of action (MOA) dramatically lags behind clinical data. In this review, we reconstruct the available basic science and clinical literature that offers support for mechanisms of both paresthesia spinal cord stimulation (P-SCS) and paresthesia-free spinal cord stimulation (PF-SCS). While P-SCS has been heavily examined since its inception, PF-SCS paradigms have recently been clinically approved with the support of limited preclinical research. Thus, wide knowledge gaps exist between their clinical efficacy and MOA. To close this gap, many rich investigative avenues for both P-SCS and PF-SCS are underway, which will further open the door for paradigm optimization, adjunctive therapies and new indications for SCS. As our understanding of these mechanisms evolves, clinicians will be empowered with the possibility of improving patient care using SCS to selectively target specific pathophysiological processes in chronic pain
Japan Initiatives of Climate Change Adaptation for Paddy Rice Commodity
This study was supported by the Experienced-Based Learning scheme of Asian Future Leaders Scholarship Program in Kyoto University (Bai Xian Asia Institute).As one of the most consumed staple crops, rice is susceptible to climate change, emphasizing the crucial need to promote the climate adaptation of rice to ensure sustainable food security. This research aims to study the climate change impact and mitigation measures in rice commodity from Japan's perspective to serve as reference for other rice-producing countries. A study case is conducted in Hyogo Prefecture, Japan. Combining literature study and interviews, this study found increasing temperature and unstable rainfall as the most impacting climate change factors to rice commodity. These factors cause decreased yield and quality in the study case area. To mitigate the impacts, several countermeasures have been implemented in Japan e.g. water management, cultivation schedule adjustment, fertilizer management, and introduction of heat-resistant cultivar. Both the literature and the interviewees agreed that while introduction of heat-resistant cultivar is the most efficient measure, it bears the highest cost, resources, and time. All in all, climate change impacts in general and vulnerability of paddy rice commodity to the impacts are relatively well observed in Japan as shown from the established tracking system and database. The mitigation measures are done in top-down approach and supported by a bottom-up manner with an organized distribution of responsibilities among the stakeholders
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