Hyper-regular graphs and high dimensional expanders

Let $G= (V,E)$ be a finite graph. For $d_0 > 0$ we say that $G$ is $d_0$-regular, if every $v\in V$ has degree $d_0$. We say that $G$ is $(d_0, d_1)$-regular, for $d_1>d_0>0$, if $G$ is $d_0$ regular and for every $v\in V$, the subgraph induced on $v$'s neighbors is $d_1$-regular. Similarly, $G$ is $(d_0, d_1,\ldots, d_{n-1})$-regular for $d_{n-1}>\ldots>d_1>d_0>0$, if $G$ is $d_0$ regular and for every $v\in V$, the subgraph induced on $v$'s neighbors is $(d_1,\ldots, d_{n-1})$-regular; In that case, we say that $G$ is an $n$-dimensional hyper-regular graph (HRG). Here we define a new kind of graph product, through which we build examples of infinite families of $n$-dimensional HRG such that the joint neighborhood of every clique of size at most $n-1$ is connected. In particular, relying on the work of Kaufman and Oppenheim, our product yields an infinite family of $n$-dimensional HRG for arbitrarily large $n$ with good expansion properties. This answers a question of Dinur regarding the existence of such objects.Comment: 27 page

Verbal and physical violence towards hospital- and community-based physicians in the Negev: an observational study

BACKGROUND: Over recent years there has been an increasing prevalence of verbal and physical violence in Israel, including in the work place. Physicians are exposed to violence in hospitals and in the community. The objective was to characterize acts of verbal and physical violence towards hospital- and community-based physicians. METHODS: A convenience sample of physicians working in the hospital and community completed an anonymous questionnaire about their experience with violence. Data collection took place between November 2001 and July 2002. One hundred seventy seven physicians participated in the study, 95 from the hospital and 82 from community clinics. The community sample included general physicians, pediatricians, specialists and residents. RESULTS: Ninety-nine physicians (56%) reported at least one act of verbal violence and 16 physicians (9%) reported exposure to at least one act of physical violence during the previous year. Fifty-one hospital physicians (53.7%) were exposed to verbal violence and 9 (9.5%) to physical violence. Forty-eight community physicians (58.5%) were exposed to verbal violence and 7 (8.5%) to physical violence. Seventeen community physicians (36.2%) compared to eleven hospital physicians (17.2%) said that the violence had a negative impact on their family and on their quality of life (p < 0.05). The most common causes of violence were long waiting time (46.2%), dissatisfaction with treatment (15.4%), and disagreement with the physician (10.3%). CONCLUSION: Verbal and/or physical violence against physicians is common in both the hospital and in community clinics. The impatience that accompanies waiting times may have a cultural element. Shortening waiting times and providing more information to patients and families could reduce the rate of violence, but a cultural change may also be required

Gestión administrativa y prestación de servicio de calidad en la gerencia regional de transportes y comunicaciones Cusco, 2022

El presente estudio de investigación tuvo como objetivo de estudio: Determinar de qué manera se relaciona la gestión administrativa en la prestación de servicio de calidad en la Gerencia Regional de Transportes y Comunicaciones Cusco, 2022, con cuyo enfoque cuantitativo con medición numérica y procedimiento estadístico para recabar y procesarlas la información, el nivel empleado fue descriptivo correlacional , ello porque permite determinar a la población de estudio así se tuvo a 50 colaboradores sean funcionarios y servidores, cuyo diseño de investigación es no experimental de corte transversal, porque se tuvo que determinar y observar la realidad, donde os datos fueron recolectados en un tiempo determinado, se aplicó la técnica de la encuesta, el instrumento empleado es el cuestionario sobre Gestión administrativa y prestación de servicio de calidad; donde dicho instrumento fue validado por expertos en gestión pública, donde tuvo opinión confiable y favorable, de donde se Concluyó que existe relación entre las variables estudiadas como es la Gestión Administrativa y Prestación de Servicio de Calidad en la Gerencia Regional de Transportes y Comunicaciones Cusco

Nitrogen and phosphorus limitation of oceanic microbial growth during spring in the Gulf of Aqaba

Bioassay experiments were performed to identify how growth of key groups within the microbial community was simultaneously limited by nutrient (nitrogen and phosphorus) availability during spring in the Gulf of Aqaba's oceanic waters. Measurements of chlorophyll a (chl a) concentration and fast repetition rate (FRR) fluorescence generally demonstrated that growth of obligate phototrophic phytoplankton was co-limited by N and P and growth of facultative aerobic anoxygenic photoheterotropic (AAP) bacteria was limited by N. Phytoplankton exhibited an increase in chl a biomass over 24 to 48 h upon relief of nutrient limitation. This response coincided with an increase in photosystem II (PSII) photochemical efficiency (F v /F m), but was preceded (within 24 h) by a decrease in effective absorption crosssection (σPSII) and electron turnover time (τ). A similar response for τ and bacterio-chl a was observed for the AAPs. Consistent with the up-regulation of PSII activity with FRR fluorescence were observations of newly synthesized PSII reaction centers via low temperature (77K) fluorescence spectroscopy for addition of N (and N + P). Flow cytometry revealed that the chl a and thus FRR fluorescence responses were partly driven by the picophytoplankton (æ10 μm) community, and in particular Synechococcus. Productivity of obligate heterotrophic bacteria exhibited the greatest increase in response to a natural (deep water) treatment, but only a small increase in response to N and P addition, demonstrating the importance of additional substrates (most likely dissolved organic carbon) in moderating the heterotrophs. These data support previous observations that the microbial community response (autotrophy relative to heterotrophy) is critically dependent upon the nature of transient nutrient enrichment. © Inter-Research 2009

Quantum-Dot Assisted Spectroscopy of Degeneracy-Lifted Landau Levels in Graphene

Energy spectroscopy of strongly interacting phases requires probes which minimize screening while retaining spectral resolution and local sensitivity. Here we demonstrate that such probes can be realized using atomic sized quantum dots bound to defects in hexagonal Boron Nitride tunnel barriers, placed at nanometric distance from graphene. With dot energies capacitively tuned by a planar graphite electrode, dot-assisted tunneling becomes highly sensitive to the graphene excitation spectrum. The spectra track the onset of degeneracy lifting with magnetic field at the ground state, and at unoccupied exited states, revealing symmetry-broken gaps which develop steeply with magnetic field - corresponding to Land\'e $g$ factors as high as 160. Measured up to $B = 33$ T, spectra exhibit a primary energy split between spin-polarized excited states, and a secondary spin-dependent valley-split. Our results show that defect dots probe the spectra while minimizing local screening, and are thus exceptionally sensitive to interacting states