9,557 research outputs found
Stability of the Brascamp-Lieb constant and applications
We prove that the best constant in the general Brascamp-Lieb inequality is a
locally bounded function of the underlying linear transformations. As
applications we deduce certain very general Fourier restriction, Kakeya-type,
and nonlinear variants of the Brascamp-Lieb inequality which have arisen
recently in harmonic analysis
Super-Resolving Quantum Radar: Coherent-State Sources with Homodyne Detection Suffice to Beat the Diffraction Limit
There has been much recent interest in quantum metrology for applications to
sub-Raleigh ranging and remote sensing such as in quantum radar. For quantum
radar, atmospheric absorption and diffraction rapidly degrades any actively
transmitted quantum states of light, such as N00N states, so that for this
high-loss regime the optimal strategy is to transmit coherent states of light,
which suffer no worse loss than the linear Beer's law for classical radar
attenuation, and which provide sensitivity at the shot-noise limit in the
returned power. We show that coherent radar radiation sources, coupled with a
quantum homodyne detection scheme, provide both longitudinal and angular
super-resolution much below the Rayleigh diffraction limit, with sensitivity at
shot-noise in terms of the detected photon power. Our approach provides a
template for the development of a complete super-resolving quantum radar system
with currently available technology.Comment: 23 pages, content is identical to published versio
Memory Reconsolidation Mediates the Updating of Hippocampal Memory Content
The retrieval or reactivation of a memory places it into a labile state, requiring a process of reconsolidation to restabilize it. This retrieval-induced plasticity is a potential mechanism for the modification of the existing memory. Following previous data supportive of a functional role for memory reconsolidation in the modification of memory strength, here I show that hippocampal memory reconsolidation also supports the updating of contextual memory content. Using a procedure that separates the learning of pure context from footshock-motivated contextual fear learning, I demonstrate doubly dissociable hippocampal mechanisms of initial context learning and subsequent updating of the neutral contextual representation to incorporate the footshock. Contextual memory consolidation was dependent upon BDNF expression in the dorsal hippocampus, whereas the footshock modification of the contextual representation required the expression of Zif268. These mechanisms match those previously shown to be selectively involved in hippocampal memory consolidation and reconsolidation, respectively. Moreover, memory reactivation is a necessary step in modifying memory content, as inhibition of hippocampal synaptic protein degradation also prevented the footshock-mediated memory modification. Finally, dorsal hippocampal knockdown of Zif268 impaired the reconsolidation of the pure contextual memory only under conditions of weak context memory training, as well as failing to disrupt contextual freezing when a strong contextual fear memory is reactivated by further conditioning. Therefore, an adaptive function of the reactivation and reconsolidation process is to enable the updating of memory content
Perspectives of healthcare providers on the nutritional management of patients on haemodialysis in Australia: An interview study
Objective To describe the perspectives of healthcare providers on the nutritional management of patients on haemodialysis, which may inform strategies for improving patient-centred nutritional care. Design Face-to-face semistructured interviews were conducted until data saturation, and thematic analysis based on principles of grounded theory. Setting 21 haemodialysis centres across Australia. Participants 42 haemodialysis clinicians (nephrologists and nephrology trainees (15), nurses (12) and dietitians (15)) were purposively sampled to obtain a range of demographic characteristics and clinical experiences. Results Six themes were identified: responding to changing clinical status (individualising strategies to patient needs, prioritising acute events, adapting guidelines), integrating patient circumstances (assimilating life priorities, access and affordability), delineating specialty roles in collaborative structures (shared and cohesive care, pivotal role of dietary expertise, facilitating access to nutritional care, perpetuating conflicting advice and patient confusion, devaluing nutritional specialty), empowerment for behaviour change (enabling comprehension of complexities, building autonomy and ownership, developing self-efficacy through engagement, tailoring self-management strategies), initiating and sustaining motivation (encountering motivational hurdles, empathy for confronting life changes, fostering non-judgemental relationships, emphasising symptomatic and tangible benefits, harnessing support networks), and organisational and staffing barriers (staffing shortfalls, readdressing system inefficiencies). Conclusions Organisational support with collaborative multidisciplinary teams and individualised patient care were seen as necessary for developing positive patient-clinician relationships, delivering consistent nutrition advice, and building and sustaining patient motivation to enable change in dietary behaviour. Improving service delivery and developing and delivering targeted, multifaceted self-management interventions may enhance current nutritional management of patients on haemodialysis
Coherent and Squeezed Vacuum Light Interferometry: Parity detection hits the Heisenberg limit
The interference between coherent and squeezed vacuum light can produce path
entangled states with very high fidelities. We show that the phase sensitivity
of the above interferometric scheme with parity detection saturates the quantum
Cramer-Rao bound, which reaches the Heisenberg-limit when the coherent and
squeezed vacuum light are mixed in roughly equal proportions. For the same
interferometric scheme, we draw a detailed comparison between parity detection
and a symmetric-logarithmic-derivative-based detection scheme suggested by Ono
and Hofmann.Comment: Change in the format from aps to iop since we decided to submit it to
NJP; Minor changes in tex
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A Framework for Analyzing Business Model Innovation in Mobile Commerce
The paper develops and tests a framework for evaluating mobile commerce business models and strategies. To study business model innovation in mobile commerce, we analyze the cost, revenue, and growth components of the business model. In addition, we also investigate whether the implementation of the new business model successfully capitalized on the key disruptive attributes of mobile commerce. An analytical framework is developed to guide the empirical study of the two leading mobile commerce companies in Taiwan. The empirical research indicates that the mobile commerce industry in Taiwan has been able to capitalize on many but not all of the value-adding mobile commerce disruptive attributes as well as the economic principles of the digital economy to provide mobile value. The development of mobile application services should be demand-driven and customer-focused, rather than merely supply- oriented. Mobile commerce service providers must understand the tacit consumer demand and be able to capture the full benefits of the disruptive technology and service innovation in order to achieve superior business performance
Memory reconsolidation in aversive and appetitive settings
Memory reconsolidation has been observed across species and in a number of behavioral paradigms. The majority of memory reconsolidation studies have been carried out in Pavlovian fear conditioning and other aversive memory settings, with potential implications for the treatment of post-traumatic stress disorder. However, there is a growing literature on memory reconsolidation in appetitive reward-related memory paradigms, including translational models of drug addiction. While there appears to be substantial similarity in the basic phenomenon and underlying mechanisms of memory reconsolidation across unconditioned stimulus valence, there are also notable discrepancies. These arise both when comparing aversive to appetitive paradigms and also across different paradigms within the same valence of memory. We review the demonstration of memory reconsolidation across different aversive and appetitive memory paradigms, the commonalities and differences in underlying mechanisms and the conditions under which each memory undergoes reconsolidation. We focus particularly on whether principles derived from the aversive literature are applicable to appetitive settings, and also whether the expanding literature in appetitive paradigms is informative for fear memory reconsolidation
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