194 research outputs found
Contrastive Moments: Unsupervised Halfspace Learning in Polynomial Time
We give a polynomial-time algorithm for learning high-dimensional halfspaces
with margins in -dimensional space to within desired TV distance when the
ambient distribution is an unknown affine transformation of the -fold
product of an (unknown) symmetric one-dimensional logconcave distribution, and
the halfspace is introduced by deleting at least an fraction of the
data in one of the component distributions. Notably, our algorithm does not
need labels and establishes the unique (and efficient) identifiability of the
hidden halfspace under this distributional assumption. The sample and time
complexity of the algorithm are polynomial in the dimension and .
The algorithm uses only the first two moments of suitable re-weightings of the
empirical distribution, which we call contrastive moments; its analysis uses
classical facts about generalized Dirichlet polynomials and relies crucially on
a new monotonicity property of the moment ratio of truncations of logconcave
distributions. Such algorithms, based only on first and second moments were
suggested in earlier work, but hitherto eluded rigorous guarantees.
Prior work addressed the special case when the underlying distribution is
Gaussian via Non-Gaussian Component Analysis. We improve on this by providing
polytime guarantees based on Total Variation (TV) distance, in place of
existing moment-bound guarantees that can be super-polynomial. Our work is also
the first to go beyond Gaussians in this setting.Comment: Preliminary version in NeurIPS 202
Recommended from our members
An Exploratory Investigation of Frontline Employeesâ Family Interferences on Job Attitudes and Service Outcomes
This study examines the negative spillover effect of hospitality frontline employeesâ work-family conflicts on their affective reactions and commitment and on customer satisfaction. As a field survey indicated, frontline employeesâ role conflicts between work and family result in less positive affective job-related reactions, decreased emotional attachment to the organization, and lower levels of customer satisfaction. The findings suggest that tourism & hospitality organizations need to be aware of how factors outside the workplace influence service excellence
Recommended from our members
An Investigation of the Effects of Front-Line Employees\u27 Work-Family Conflict on Customer Satisfaction through Exhaustion and Emotional Displays
The present study investigates the distal effects of front-line employees\u27 work-family conflict on customer satisfaction. Based on data from 200 paired employee-customer interactions at six hotels, a Structural Equation Modeling was conducted to test the hypothesized model and the results supported most of our predictions. Specifically, participants\u27 FIW (family interfering with work) was positively linked to physical, emotional, and mental exhaustion, while WIF (work interfering with family) did not have such associations. Further, individuals with higher levels of physical exhaustion were more likely to manage their emotions by faking positive emotions and suppressing negative emotions, whereas participants with higher levels of emotional exhaustion were more likely to fake positive emotions. Although faking positive emotions enhances the employee\u27s role performance, such actions failed to enhance customer satisfaction. The current research extends our knowledge of work-family conflict on employee-customer interactions and suggests that hospitality organizations need to be aware of the critical effects of employees\u27 family affairs on work behaviors and ultimately on customer satisfaction
Monocyte Metabolic Reprogramming Promotes Pro-Inflammatory Activity and Staphylococcus Aureus Biofilm Clearance
Biofilm-associated prosthetic joint infections (PJIs) cause significant morbidity due to their recalcitrance to immune-mediated clearance and antibiotics, with Staphylococcus aureus (S. aureus) among the most prevalent pathogens. We previously demonstrated that S. aureus biofilm-associated monocytes are polarized to an anti-inflammatory phenotype and the adoptive transfer of pro-inflammatory macrophages attenuated biofilm burden, highlighting the critical role of monocyte/macrophage inflammatory status in dictating biofilm persistence. The inflammatory properties of leukocytes are linked to their metabolic state, and here we demonstrate that biofilm-associated monocytes exhibit a metabolic bias favoring oxidative phosphorylation (OxPhos) and less aerobic glycolysis to facilitate their anti-inflammatory activity and biofilm persistence. To shift monocyte metabolism in vivo and reprogram cells to a pro-inflammatory state, a nanoparticle approach was utilized to deliver the OxPhos inhibitor oligomycin to monocytes. Using a mouse model of S. aureus PJI, oligomycin nanoparticles were preferentially internalized by monocytes, which significantly reduced S. aureus biofilm burden by altering metabolism and promoting the pro-inflammatory properties of infiltrating monocytes as revealed by metabolomics and RT-qPCR, respectively. Injection of oligomycin alone had no effect on monocyte metabolism or biofilm burden, establishing that intracellular delivery of oligomycin is required to reprogram monocyte metabolic activity and that oligomycin lacks antibacterial activity against S. aureus biofilms. Remarkably, monocyte metabolic reprogramming with oligomycin nanoparticles was effective at clearing established biofilms in combination with systemic antibiotics. These findings suggest that metabolic reprogramming of biofilm-associated monocytes may represent a novel therapeutic approach for PJI
Simple synthetic routes to carbene-M-amido (M=Cu, Ag, Au) complexes for luminescence and photocatalysis applications
The development of novel and operationally simple synthetic routes to carbene-metal-amido (CMA) complexes of copper, silver and gold relevant for photonic applications are reported. A mild base and sustainable solvents allow all reactions to be conducted in air and at room temperature, leading to high yields of the targeted compounds even on multigram scales. The effect of various mild bases on the NâH metallation was studied in silico and experimentally, while a mechanochemical, solvent-free synthetic approach was also developed. Our photophysical studies on [M(NHC)(Cbz)] (Cbz=carbazolyl) indicate that the occurrence of fluorescent or phosphorescent states is determined primarily by the metal, providing control over the excited state properties. Consequently, we demonstrate the potential of the new CMAs beyond luminescence applications by employing a selected CMA as a photocatalyst. The exemplified synthetic ease is expected to accelerate the applications of CMAs in photocatalysis and materials chemistry
Wannier-function description of the electronic polarization and infrared absorption of high-pressure hydrogen
We have constructed maximally-localized Wannier functions for prototype
structures of solid molecular hydrogen under pressure, starting from LDA and
tight-binding Bloch wave functions. Each occupied Wannier function can be
associated with two paired protons, defining a ``Wannier molecule''. The sum of
the dipole moments of these ``molecules'' always gives the correct macroscopic
polarization, even under strong compression, when the overlap between nearby
Wannier functions becomes significant. We find that at megabar pressures the
contributions to the dipoles arising from the overlapping tails of the Wannier
functions is very large. The strong vibron infrared absorption experimentally
observed in phase III, above ~ 150 GPa, is analyzed in terms of the
vibron-induced fluctuations of the Wannier dipoles. We decompose these
fluctuations into ``static'' and ``dynamical'' contributions, and find that at
such high densities the latter term, which increases much more steeply with
pressure, is dominant.Comment: 17 pages, two-column style with 14 postscript figures embedded. Uses
REVTEX and epsf macro
Variants in the zinc transporter-3 encoding gene (SLC30A3) in schizophrenia and bipolar disorder: effects on brain glutamateâA pilot study
Zinc transporter 3 (ZnT3) has been implicated in the aetiopathology of schizophrenia. In this pilot study, we tested the hypothesis that the presence of a minor allele of two variants in the gene encoding ZnT3 (SLC30A3) affects brain glutamate and cognitive activity in patients with schizophrenia and bipolar affective disorder. Fifteen patients with schizophrenia (SCZ), 15 with bipolar affective disorder type 2 (BD), and 14 healthy volunteers (HV) were genotyped for two SLC30A3 single nucleotide polymorphisms (rs11126936 and rs11126929). They also underwent structural and functional MRI (n-back) imaging as well as static (PRESS) and functional magnetic resonance spectroscopy (n-back) on a 3 Tesla MRI system. SCZ with at least one copy of the minor allele showed reductions in dorsal anterior cingulate cortex glutamate during the n-back task, whereas SCZ without the minor allele showed an increase in glutamate. BD with the minor allele had reduced glutamate in the anterior cingulate cortex (p < 0.05). There was no effect of SLC30A3 genotype on BOLD activation during n-back or on cortical brain volume. This study supports the further investigation of SLC30A3 and its role in glutamatergic neurotransmission and in the neuropathology of mental illness
Adapting a generic tuberculosis control operational guideline and scaling it up in China: a qualitative case study
<p>Abstract</p> <p>Background</p> <p>The TB operational guideline (the <it>deskguide</it>) is a detailed action guide for county TB doctors aiming to improve the quality of DOTS, while the China national TB policy guide is a guide to TB control that is comprehensive but lacks operational usability for frontline TB doctors. This study reports the process of deskguide adaptation, its scale-up and lessons learnt for policy implications.</p> <p>Methods</p> <p>The deskguide was translated, reviewed, and revised in a working group process. Details of the eight adaptation steps are reported here. An operational study was embedded in the adaptation process. Two comparable prefectures were chosen as pilot and control sites in each of two participating provinces. In the pilot sites, the deskguide was used with the national policy guide in routine in-service training and supervisory trips; while in the control sites, only the national policy guide was used. In-depth interviews and focus groups were conducted with 16 county TB doctors, 16 township doctors, 17 village doctors, 63 TB patients and 57 patient family members. Following piloting, the deskguide was incorporated into the national TB guidelines for county TB dispensary use.</p> <p>Results</p> <p>Qualitative research identified that the deskguide was useful in the daily practice of county TB doctors. Patients in the pilot sites had a better knowledge of TB and better treatment support compared with those in the control sites.</p> <p>Conclusion</p> <p>The adaptation process highlighted a number of general strategies to adapt generic guidelines into country specific ones: 1) local policy-makers and practitioners should have a leading role; 2) a systematic working process should be employed with capable focal persons; and 3) the guideline should be embedded within the current programmes so it is sustainable and replicable for further scale-up.</p
- âŠ