1,675 research outputs found
Asymptotic Spectral Flow
In this paper we study the asymptotic behavior of the spectral flow of a
one-parameter family of Dirac operators acting on the spinor bunldle
twisted by a vector bundle of rank , with the parameter
when gets sufficiently large. Our method uses the variation of eta
invariant and local index theory technique. The key is a uniform estimate of
the eta invariant which is established via local index theory
technique and heat kernel estimate
Book Review: The Impact of Feedback in Higher Education: Improving Assessment Outcomes for Learners
The editors of this book gathered the leading international researchers across diverse disciplines and proposed four questions to guide feedback research and practice, βDo learners know the purpose of feedback and their role(s) in it? Can learners make sense of the information? Can learners take action? What effects should we be looking for?β (Henderson et al., 2019, p. 14). With the sociocultural perspective, we attempt not only to discuss, in the broad context of higher education, critical issues pertaining to feedback that makes a difference, expanding notions of feedback impact, pedagogies of feedback impact, visibility of feedback, and implications for research and practice, but to correlate the conclusions drawn from this book with the contexts and issues associated with feedback on L2 writing
Phase resetting reveals network dynamics underlying a bacterial cell cycle
Genomic and proteomic methods yield networks of biological regulatory
interactions but do not provide direct insight into how those interactions are
organized into functional modules, or how information flows from one module to
another. In this work we introduce an approach that provides this complementary
information and apply it to the bacterium Caulobacter crescentus, a paradigm
for cell-cycle control. Operationally, we use an inducible promoter to express
the essential transcriptional regulatory gene ctrA in a periodic, pulsed
fashion. This chemical perturbation causes the population of cells to divide
synchronously, and we use the resulting advance or delay of the division times
of single cells to construct a phase resetting curve. We find that delay is
strongly favored over advance. This finding is surprising since it does not
follow from the temporal expression profile of CtrA and, in turn, simulations
of existing network models. We propose a phenomenological model that suggests
that the cell-cycle network comprises two distinct functional modules that
oscillate autonomously and couple in a highly asymmetric fashion. These
features collectively provide a new mechanism for tight temporal control of the
cell cycle in C. crescentus. We discuss how the procedure can serve as the
basis for a general approach for probing network dynamics, which we term
chemical perturbation spectroscopy (CPS)
Rare diseases in developing countries: Insights from China's collaborative network
Rare diseases (RDs) are complex conditions and a worldwide healthcare challenge. The healthcare policymakers in developing countries lack templates from countries at the same level of development. This article introduced and discussed the combination of topβdown strategies and bottomβup interventions in addressing RDs in a developing country, China, as an example. The government leads the formulation of laws, policies, and guidance to coordinate national resources, while local authorities and nongovernment organisations (NGOs) are responsible for policy localisation and complement policy gaps. This article may inspire other developing countries of improving RD healthcare
Adaptation Of Maternal Skeletal Mechano-Responsiveness, Osteocyte Microenvironment, And Bone Marrow Adipocytes In Response To Reproduction And Lactation
Pregnancy and lactation induce drastic changes in skeletal physiology due to the increased calcium demand by fetal/infant growth. Although both clinical and animal studies have suggested that reproduction leads to long-lasting skeletal changes to exert protective effects on mechanical functions of maternal skeleton when subjected to estrogen deficiency, the underlying innate compensatory mechanisms at the cellular level remain unknown. Recent studies have suggested that osteocytes, the presumed mechano-sensors in bone, can actively remodel their peri-lacunar/canalicular bone matrix during lactation, and thus affecting boneβs mechano-sensitivity. Therefore, our first goal of this thesis was to determine both immediate and long-term effects of reproduction and lactation on bone mechano-sensitivity and osteocyte microenvironment in a rat model. Our study demonstrated an improved bone mechano-responsiveness in rats during lactation, possibly resulting from the elevated lactation-associated osteocyte peri-lacunar/canalicular remodeling (PLR) activities. Furthermore, when subjected to estrogen deficiency, the history of reproduction and lactation may prime the microenvironment of osteocytes through active PLR, leading to elevated mechano-sensitivity to protect maternal skeleton against estrogen deficiency. In addition to mechano-sensitivity and osteocytes, regulation of bone marrow adipocytes (BMAs) during reproduction and lactation may also contribute to exerting protective effects on skeletal metabolic homeostasis. Therefore, our second goal of this thesis was to investigate the immediate and long-term effects of reproduction and lactation on adipogenic capacity of mesenchymal progenitors and BMAs by both rat and mouse models. Our study in the inducible AdipoqCreER:TdTomato mice suggested a functional adaptation in BMAs through dynamic lipid alterations during one reproductive cycle. Moreover, when subjected to estrogen deficiency, rats with reproductive history showed lower adipogenic capacity and marked reduction in BMAs than virgins, indicating a protective effect of lactation history against estrogen-deficiency-induced bone marrow adiposity later in life. Taken together, this work explored the amazing functional adaptive mechanisms, at the cellular level, that protect women with a history of lactation from postmenopausal risks, providing important insights for osteoporosis prevention, management, and treatment in postmenopausal women by considering their lactation history
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