474 research outputs found
Multi-Cell Interference Exploitation: Enhancing the Power Efficiency in Cell Coordination
In this paper, we propose a series of novel coordination schemes for multi-cell downlink communication. Starting
from full base station (BS) coordination, we first propose a
fully-coordinated scheme to exploit beneficial effects of both
inter-cell and intra-cell interference, based on sharing both
channel state information (CSI) and data among the BSs. To
reduce the coordination overhead, we then propose a partiallycoordinated scheme where only intra-cell interference is designed
to be constructive while inter-cell is jointly suppressed by the
coordinated BSs. Accordingly, the coordination only involves
CSI exchange and the need for sharing data is eliminated.
To further reduce the coordination overhead, a third scheme
is proposed, which only requires the knowledge of statistical
inter-cell channels, at the cost of a slight increase on the
transmission power. For all the proposed schemes, imperfect
CSI is considered. We minimize the total transmission power in
terms of probabilistic and deterministic optimizations. Explicitly,
the former statistically satisfies the usersâ signal-to-interferenceplus-noise ratio (SINR) while the latter guarantees the SINR
requirements in the worst case CSI uncertainties. Simulation
verifies that our schemes consume much lower power compared
to the existing benchmarks, i.e., coordinated multi-point (CoMP)
and coordinated-beamforming (CBF) systems, opening a new
dimension on multi-cell coordination
Complex Scaled Spectrum Completeness for Coupled Channels
The Complex Scaling Method (CSM) provides scattering wave functions which
regularize resonances and suggest a resolution of the identity in terms of such
resonances, completed by the bound states and a smoothed continuum. But, in the
case of inelastic scattering with many channels, the existence of such a
resolution under complex scaling is still debated. Taking advantage of results
obtained earlier for the two channel case, this paper proposes a representation
in which the convergence of a resolution of the identity can be more easily
tested. The representation is valid for any finite number of coupled channels
for inelastic scattering without rearrangement.Comment: Latex file, 13 pages, 4 eps-figure
Peer victimisation in early childhood; observations of participant roles and sex differences
During middle childhood and adolescence, victimisation appears to be a group process involving different participant roles. However, peer reports with younger children (four to six years old) have failed to identify the participant roles of assistant (to the bully) reinforcers or defenders with much reliability. This may be because peer victimisation is a more dyadic process among younger children (behavioural reality), or because of limitations in young childrenâs cognitive capacity to identify these behaviours (cognitive limitations). The findings of an observational study which examined the group nature of peer victimisation among young children are presented. Observations were made of 56 children aged four and five years using time sampling during free play at school (totalling 43.5 h of observation). Records were made of their behaviour when an onlooker witnessed aggression by others, and also of othersâ behaviour when they were being aggressive or being victimised. Although children other than the aggressor and target were present in nearly two thirds of the episodes of peer victimisation observed, few exhibited behavioural responses in line with the assistant, reinforcer or defender roles. This supports the behavioural reality rather than the cognitive limitations explanation. Sex differences were observed in types of aggression displayed by children, with boys more likely than girls to be physically aggressive. Children were less likely to be aggressive to other-sex peers and were most likely to be victimised by children of the same sex as them. There were also sex differences in childrenâs onlooker behaviour. The implications for our understanding of the development of peer victimisation and bullying in children are discussed
Electron microscopy as an emerging analytical tool for characterizing vaccines
Characterization of nanoparticles and biologics is a critical step in the development of important new pharmaceutical products and biosimilars. Biologics pose unique characterization challenges that require an interdisciplinary approach in which several orthogonal methods are used to provide a complete picture. The physical characteristics of a biological product include properties such as the size, shape, morphology and aggregation state of the particles. These properties are often dependent on the specific environment of the particles and thus ideally must be assessed under conditions that reflect the final formulation of the pharmaceutical. Electron microscopy (EM) and in particular cryo-electron microscopy (cryoEM), has a unique advantage in that it provides a direct means of observing the individual particles in a sample, preserved in their natural hydrated state (cryoEM), simultaneously providing information on homogeneity, size distribution, titer, morphology, preservation state, flexibility, and aggregation state. For particles with a regular size and shape, particle averaging methods can provide 3D structural information, complementing X-ray crystallography analysis.
We will demonstrate the use of EM as an analytical and structural characterization tool by presenting a number of case studies as highlights. Specifically, we will discuss the characterization of Human Papilloma Virus (HPV) VLPs in GARDASILÂź, including the structure of the VLPs alone, on adjuvants, and when interacting with neutralizing antibodies [1]. We will also show how TEM was used as a non-intrusive tool to understand the structure and function of Hepatitis B surface antigen (rHBsAg) VLPs, the active component in the HBV vaccine [2]. We will furthermore demonstrate how TEM can be used to provide supporting information for characterization of a biosimilar drug delivery nanoparticle, a recombinant tuberculosis vaccine antigen, interacting with a lipid-based adjuvant [3], and a bi-specific, tetravalent immunoglobulin G-like molecule [4].
References:
[1] Zhao Q, et al. 2013. Characterization of virus-like particles in GARDASIL(R) by cryo transmission electron microscopy. Hum Vaccin Immunother.10:1-6.
[2] Mulder AM, et al. 2012. Toolbox for non-intrusive structural and functional analysis of recombinant VLP based vaccines: a case study with hepatitis B vaccine. PLoS One 7:e33235.
[3] Fox CB, et al. 2014. Cryogenic transmission electron microscopy of recombinant tuberculosis vaccine antigen with anionic liposomes reveals formation of flattened liposomes. Int J Nanomedicine 9:1367-77.
[4] Correia I, et al. 2013.The structure of dual-variable-domain immunoglobulin molecules alone and bound to antigen. MAbs. 5:364-72
Dynamics of direct inter-pack encounters in endangered African wild dogs
Aggressive encounters may have important life history consequences due to the potential for injury and death, disease transmission, dispersal opportunities or exclusion from key areas of the home range. Despite this, little is known of their detailed dynamics, mainly due to the difficulties of directly observing encounters in detail. Here, we describe detailed spatial dynamics of inter-pack encounters in African wild dogs (Lycaon pictus), using data from custom-built high-resolution GPS collars in 11 free-ranging packs. On average, each pack encountered another pack approximately every 7 weeks and met each neighbour twice each year. Surprisingly, intruders were more likely to win encounters (winning 78.6% of encounters by remaining closer to the site in the short term). However, intruders did tend to move farther than residents toward their own range core in the short-term (1 h) post-encounter, and if this were used to indicate losing an encounter, then the majority (73.3%) of encounters were won by residents. Surprisingly, relative pack size had little effect on encounter outcome, and injuries were rare (<15% of encounters). These results highlight the difficulty of remotely scoring encounters involving mobile participants away from static defendable food resources. Although inter-pack range overlap was reduced following an encounter, encounter outcome did not seem to drive this, as both packs shifted their ranges post-encounter. Our results indicate that inter-pack encounters may be lower risk than previously suggested and do not appear to influence long-term movement and ranging
Depression and Anxiety During the COVID-19 Pandemic in an Urban, Low-Income Public University Sample
Mental health disparities in the aftermath of national disasters and the protective role of socioeconomic status are both well documented. We assessed the prevalence of depression and anxiety symptoms among underresourced public university students during the COVID-19 pandemic in New York City. Between April 8, 2020, and May 2, 2020, adult students (N = 1,821) across the CUNY system completed an online survey examining COVID-19ârelated stressors and mental health and sociodemographic factors. Using multivariable logistical regression to assess the association between COVID-19ârelated stressors and depression and anxiety symptoms, we found a high prevalence and severity of depression and anxiety symptoms. We also observed that more exposure to COVID-19ârelated stressors was associated with increased depressive (27.0%, 41.4%, and 63.1% for low-, medium-, and high-level stressors, respectively) and anxiety symptoms (19.3%, 34.6%, 52.2%). In addition, the degree of exposure to COVID-19ârelated stressors served as an important predictor of depression and anxiety symptoms. Compared to high levels of stressors, the odds of depression were 0.2, 95% CI [0.2, 0.3] for low- and 0.4, 95% CI [0.3, 0.5] for medium-level stressors; for anxiety, the odds were 0.2, 95% CI [0.2, 0.3] for low and 0.05, 95% CI [0.4, 0.6] for medium stressors. Finally, household savings of less than $5,000 increased the risk of anxiety but not depression symptoms, OR = 1.3, 95% CI [1.0,1.6]. Together, these findings tell a devastating story of psychological distress among students from lower socioeconomic groups living in the COVID-19 epicenter of the U.S. pandemic
Three-body resonances in He-6, Li-6, and Be-6, and the soft dipole mode problem of neutron halo nuclei
Using the complex scaling method, the low-lying three-body resonances of
He, Li, and Be are investigated in a parameter-free microscopic
three-cluster model. In He a 2, in Li a 2 and a 1, and in
Be the 0 ground state and a 2 excited state is found. The other
experimentally known 2 state of Li cannot be localized by our present
method. We have found no indication for the existence of the predicted 1
soft dipole state in He. We argue that the sequential decay mode of He
through the resonant states of its two-body subsystem can lead to peaks in the
excitation function. This process can explain the experimental results in the
case of Li, too. We propose an experimental analysis, which can decide
between the soft dipole mode and the sequential decay mode.Comment: REVTEX, Submitted to Phys. Rev. C, 12 pages, 2 postscript figures are
available upon request. CALTECH, MAP-16
Removing the Microlensing Blending-Parallax Degeneracy Using Source Variability
Microlensing event MACHO 97-SMC-1 is one of the rare microlensing events for
which the source is a variable star, simply because most variable stars are
systematically eliminated from microlensing studies. Using observational data
for this event, we show that the intrinsic variability of a microlensed star is
a powerful tool to constrain the nature of the lens by breaking the degeneracy
between the microlens parallax and the blended light. We also present a
statistical test for discriminating the location of the lens based on the
\chi^2 contours of the vector \Lambda, the inverse of the projected velocity.
We find that while SMC self lensing is somewhat favored over halo lensing,
neither location can be ruled out with good confidence.Comment: 15 text pages + 2 tables + 7 figures. Published in the Astrophysical
Journa
- âŠ