628 research outputs found
Multi-Way Relay Networks: Orthogonal Uplink, Source-Channel Separation and Code Design
We consider a multi-way relay network with an orthogonal uplink and
correlated sources, and we characterise reliable communication (in the usual
Shannon sense) with a single-letter expression. The characterisation is
obtained using a joint source-channel random-coding argument, which is based on
a combination of Wyner et al.'s "Cascaded Slepian-Wolf Source Coding" and
Tuncel's "Slepian-Wolf Coding over Broadcast Channels". We prove a separation
theorem for the special case of two nodes; that is, we show that a modular code
architecture with separate source and channel coding functions is
(asymptotically) optimal. Finally, we propose a practical coding scheme based
on low-density parity-check codes, and we analyse its performance using
multi-edge density evolution.Comment: Authors' final version (accepted and to appear in IEEE Transactions
on Communications
The Three-User Finite-Field Multi-Way Relay Channel with Correlated Sources
This paper studies the three-user finite-field multi-way relay channel, where
the users exchange messages via a relay. The messages are arbitrarily
correlated, and the finite-field channel is linear and is subject to additive
noise of arbitrary distribution. The problem is to determine the minimum
achievable source-channel rate, defined as channel uses per source symbol
needed for reliable communication. We combine Slepian-Wolf source coding and
functional-decode-forward channel coding to obtain the solution for two classes
of source and channel combinations. Furthermore, for correlated sources that
have their common information equal their mutual information, we propose a new
coding scheme to achieve the minimum source-channel rate.Comment: Author's final version (accepted and to appear in IEEE Transactions
on Communications
The Finite Field Multi-Way Relay Channel with Correlated Sources: The Three-User Case
The three-user finite field multi-way relay channel with correlated sources
is considered. The three users generate possibly correlated messages, and each
user is to transmit its message to the two other users reliably in the Shannon
sense. As there is no direct link among the users, communication is carried out
via a relay, and the link from the users to the relay and those from the relay
to the users are finite field adder channels with additive noise of arbitrary
distribution. The problem is to determine the set of all possible achievable
rates, defined as channel uses per source symbol for reliable communication.
For two classes of source/channel combinations, the solution is obtained using
Slepian-Wolf source coding combined with functional-decode-forward channel
coding.Comment: to be presented at ISIT 201
Dysregulation of ErbB4 Signaling Pathway in the Dorsal Hippocampus after Neonatal Hypoxia-Ischemia and Late Deficits in PV+ Interneurons, Synaptic Plasticity and Working Memory
Neonatal hypoxic-ischemic (HI) injury leads to deficits in hippocampal parvalbumin (PV)+ interneurons (INs) and working memory. Therapeutic hypothermia (TH) does not prevent these deficits. ErbB4 supports maturation and maintenance of PV+ IN. Thus, we hypothesized that neonatal HI leads to persistent deficits in PV+ INs, working memory and synaptic plasticity associated with ErbB4 dysregulation despite TH. P10 HI-injured mice were randomized to normothermia (NT, 36 °C) or TH (31 °C) for 4 h and compared to sham. Hippocampi were studied for α-fodrin, glial fibrillary acidic protein (GFAP), and neuroregulin (Nrg) 1 levels; erb-b2 receptor tyrosine kinase 4 (ErbB4)/ Ak strain transforming (Akt) activation; and PV, synaptotagmin (Syt) 2, vesicular-glutamate transporter (VGlut) 2, Nrg1, and ErbB4 expression in coronal sections. Extracellular field potentials and behavioral testing were performed. At P40, deficits in PV+ INs correlated with impaired memory and coincided with blunted long-term depression (LTD), heightened long-term potentiation (LTP) and increased Vglut2/Syt2 ratio, supporting excitatory-inhibitory (E/I) imbalance. Hippocampal Nrg1 levels were increased in the hippocampus 24 h after neonatal HI, delaying the decline documented in shams. Paradoxically ErbB4 activation decreased 24 h and again 30 days after HI. Neonatal HI leads to persistent deficits in hippocampal PV+ INs, memory, and synaptic plasticity. While acute decreased ErbB4 activation supports impaired maturation and survival after HI, late deficit reemergence may impair PV+ INs maintenance after HI
Patient and Provider Perspectives on HIV and HIV-Related Stigma in Dutch Health Care Settings
Ensuring that people living with HIV (PLWH) feel accepted in health care settings is imperative. This mixed methods study explored the perspectives of PLWH and health professionals on their interactions. A total of 262 predominantly gay men of Dutch origin participated in a survey study of possible negative interactions with health professionals, and semi-structured interviews were subsequently conducted with 22 PLWH and 14 health professionals. Again, most PLWH were gay men of Dutch origin. All health professionals were Dutch. PLWH reported negative experiences with health professionals including awkward interactions, irrelevant questions, rude treatment, blame, pity, excessive or differential precautions, care refusal, unnecessary referrals, delayed treatment, poor support, and confidentiality breaches. They also reported positive experiences including equal treatment, being valued as a partner in one's health, social support provision, and confidentiality assurances. Health professionals reported having little experience with PLWH and only basic knowledge of HIV. They contended that PLWH are treated equally and that HIV is no longer stigmatized, but also reported fear of occupational infection, resulting in differential precautions. Additionally, they conveyed labeling PLWH's files to warn others, and curiosity regarding how patients acquired HIV. The findings suggest that there is a gap in perception between PLWH and health professionals regarding the extent to which negative interactions occur, and that these interactions should be improved. Implications for stigma reduction and care optimization are discussed
The Chromatin Remodelling Factor dATRX Is Involved in Heterochromatin Formation
Despite extensive study of heterochromatin, relatively little is known about the mechanisms by which such a structure forms. We show that the Drosophila homologue of the human α-thalassemia and mental retardation X-linked protein (dATRX), is important in the formation or maintenance of heterochromatin through modification of position effect variegation. We further show that there are two isoforms of the dATRX protein, the longer of which interacts directly with heterochromatin protein 1 (dHP-1) through a CxVxL motif both in vitro and in vivo. These two proteins co-localise at heterochromatin in a manner dependent on this motif. Consistent with this observation, the long isoform of the dATRX protein localises primarily to the heterochromatin at the chromocentre on salivary gland polytene chromosomes, whereas the short isoform binds to many sites along the chromosome arms. We suggest that the establishment of a regular nucleosomal organisation may be common to heterochromatin and transcriptionally repressed chromatin in other locations, and may require the action of ATP dependent chromatin remodelling factors
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