Quasi-Concavity for Gaussian Multicast Relay Channels

Standard upper and lower bounds on the capacity of relay channels are cut-set (CS), decode-forward (DF), and quantize-forward (QF) rates. For real additive white Gaussian noise (AWGN) multicast relay channels with one source node and one relay node, these bounds are shown to be quasi-concave in the receiver signal-to-noise ratios and the squared source-relay correlation coefficient. Furthermore, the CS rates are shown to be quasi-concave in the relay position for a fixed correlation coefficient, and the DF rates are shown to be quasi-concave in the relay position. The latter property characterizes the optimal relay position when using DF.Comment: Shortened version of a document that appeared as an open access paper at https://www.mdpi.com/1099-4300/21/2/10

Optimal relay location and power allocation for low SNR broadcast relay channels

We consider the broadcast relay channel (BRC), where a single source transmits to multiple destinations with the help of a relay, in the limit of a large bandwidth. We address the problem of optimal relay positioning and power allocations at source and relay, to maximize the multicast rate from source to all destinations. To solve such a network planning problem, we develop a three-faceted approach based on an underlying information theoretic model, computational geometric aspects, and network optimization tools. Firstly, assuming superposition coding and frequency division between the source and the relay, the information theoretic framework yields a hypergraph model of the wideband BRC, which captures the dependency of achievable rate-tuples on the network topology. As the relay position varies, so does the set of hyperarcs constituting the hypergraph, rendering the combinatorial nature of optimization problem. We show that the convex hull C of all nodes in the 2-D plane can be divided into disjoint regions corresponding to distinct hyperarcs sets. These sets are obtained by superimposing all k-th order Voronoi tessellation of C. We propose an easy and efficient algorithm to compute all hyperarc sets, and prove they are polynomially bounded. Using the switched hypergraph approach, we model the original problem as a continuous yet non-convex network optimization program. Ultimately, availing on the techniques of geometric programming and $p$-norm surrogate approximation, we derive a good convex approximation. We provide a detailed characterization of the problem for collinearly located destinations, and then give a generalization for arbitrarily located destinations. Finally, we show strong gains for the optimal relay positioning compared to seemingly interesting positions.Comment: In Proceedings of INFOCOM 201

Chatbots on Messaging Platform Revolution in app world

In the era of heavy mobile and desktop based apps Chatbots are the premier option which is very fast and lightweight. Chatbots can work against our regular apps that too on our most used messaging application. Chatbots can be created on most popular platforms (like messenger, telegram, slack, twitter, Skype). Some of the Chatbots building platforms allow us to create it in a jiffy

On the geometry of wireless network multicast in 2-D

We provide a geometric solution to the problem of optimal relay positioning to maximize the multicast rate for low-SNR networks. The networks we consider, consist of a single source, multiple receivers and the only intermediate and locatable node as the relay. We construct network the hypergraph of the system nodes from the underlying information theoretic model of low-SNR regime that operates using superposition coding and FDMA in conjunction (which we call the "achievable hypergraph model"). We make the following contributions. 1) We show that the problem of optimal relay positioning maximizing the multicast rate can be completely decoupled from the flow optimization by noticing and exploiting geometric properties of multicast flow. 2) All the flow maximizing the multicast rate is sent over at most two paths, in succession. The relay position is dependent only on one path (out of the two), irrespective of the number of receiver nodes in the system. Subsequently, we propose simple and efficient geometric algorithms to compute the optimal relay position. 3) Finally, we show that in our model at the optimal relay position, the difference between the maximized multicast rate and the cut-set bound is minimum. We solve the problem for all (Ps,Pr) pairs of source and relay transmit powers and the path loss exponent \alpha greater than 2

IN VITRO ABSORPTION STUDY OF CARBAMAZEPINE SOLID DISPERSION USING EVERTED GUT SAC METHOD

The oral Bioavailability of BCS (Bio Pharmaceutical Classification System) class II drug with poor solubility and reasonable permeability is limited by drug dissolution. In order to improve the aqueous solubility of the drug and dissolution of thedrug, the solid dispersion was prepared and evaluated for its absorption in intestine using modified everted gut sac method. The solid dispersion of carbamezepine (CBZ) was prepared using polaxomer and guargum by kneading method. The CBZ and CBZSD (Solid Disposisi) shows 2.329% and 3.948% drug absorption, respectively. The data show that solid dispersion increase the absorption of the CBZ in CBZ-SD is more than 70% in comparison to pure CBZ. The increase in CBZ solubility of the SD could be attributed to several factors such as improved wettability, local solubilization, drug particle size reduction and crystalline or, interstitial solid solution reduction. Key words: Everted gut sac method, solid dispersion, absorption, solubilit

Treatment of clavicle fracture using wise lock clavicle hook plate and wise lock superior anterior clavicle plate

Background: Clavicle fracture is common in adults associated with high non-union rate and post-operative complications. The aim of this prospective study was to reduce the postoperative complications in clavicle fracture (Type 15-A2 and 15-B1) by using wise lock plates (manufactured by Auxein Medical Private Limited).Methods: In this prospective study of 25 patients (11 patients had 15-A2 fracture, 14 patients had 15-B1 fracture) recruited with one year follows up period followed by physical exercises after one month of the surgery. The fractures were treated with two different plates: 3.5 mm wise lock clavicle hook plate and 3.5 mm wise lock superior anterior clavicle plate. X-ray was used to check the union, non-union. Functional outcome of the patients were assessed by the visual analogue scale (VAS) score at post-operative follow up at 4 weeks, 12 weeks, 6 months and 1 year.Results: Postoperative outcome was good with none of the patients showing non-union or delay in the union of fracture site. The encountered complication registered were residual pain which was mild (4 cases), and hypoesthesia (2 cases).Conclusions: Osteosynthesis of clavicle fracture with 3.5 mm diameter locking plates attributed as superior, anterior and hook plating system showed excellent results with low rate of complications

Schizencephaly: a rare case with early diagnosis, management and review of literature

Schizencephaly or split brain is an uncommon congenital disorder of cerebral cortical development, belonging to the group of cell migration defects. It is characterized by the presence of a cleft in the brain extending from the surface of the piamater to the cerebral ventricles. A 21-year-old primigravida at 19+2 weeks of gestation was referred to our Outpatient department with a level-2 ultrasound done at 18+2 weeks suggestive of schizencephaly. First trimester genetic screening was not done. Quadruple testing was normal. After genetic consultation and poor prognostication by neonatologist, decision for medical termination of pregnancy was taken. Patient underwent medical termination with mifepristone -misoprostol regimen. A female abortus weighing 200 gm was delivered. Gross examination showed only facial malformation in the form of cleft lip and hypoplastic nose. Infantogram did not reveal any skeletal deformity. On fetal autopsy, findings were consistent with the diagnosis of schizencephaly (type 1). Schizencephaly is a rare disorder in prenatal medicine with grave prognosis. Majority of cases are either diagnosed at late gestation or present in the first decade of life. Hence with periodic surveillance during antenatal care and help of ultrasonography, such rare and serious congenital malformations can be diagnosed and managed at an early stage

Polydopamine-Enabled Biomimetic Surface Engineering of Materials:New Insights and Promising Applications

Surface modification is an important approach to modify the properties of materials. Numerous approaches have been adopted to tailor the properties of such materials, which have been proven successful at many scales and parameters. However, most of these techniques are often tedious, poorly adhesive, costly, sometimes hazardous, and surface-specific, hence cannot be extended on a large scale and all kinds of surfaces. These shortcomings have led to the emergence of new dopamine (DA) based green surface modification technique where a thin polydopamine (PDA) layer is deposited on surfaces through a facile polymerization of DA under alkaline conditions to enable the surface for various applications. This surface modification strategy has several advantages over other techniques in deposition processing under mild conditions, cost-effective and straightforward ingredients, and applicability to all kinds of surfaces regardless of their sizes, shapes, and types. Moreover, the PDA layer enhances the surface functionality. Therefore, it can serve as a versatile platform for various secondary reactions for a wide range of applications. Herein, the chemistry of DA is summarized and its polymerized form PDA for the modification of different families of materials’ surfaces with an emphasis on energy, environmental and biological applications.</p

Biogenic Preparation, Characterization, and Biomedical Applications of Chitosan Functionalized Iron Oxide Nanocomposite

Chitosan (CS) functionalization over nanomaterials has gained more attention in the biomedical field due to their biocompatibility, biodegradability, and enhanced properties. In the present study, CS functionalized iron (II) oxide nanocomposite (CS/FeO NC) was prepared using Sida acuta leaf extract by a facile and eco-friendly green chemistry route. Phyto-compounds of S. acuta leaf were used as a reductant to prepare CS/FeO NC. The existence of CS and FeO crystalline peaks in CS/FeO NC was confirmed by XRD. FE-SEM analysis revealed that the prepared CS/FeO NC were spherical with a 10&ndash;100 nm average size. FTIR analyzed the existence of CS and metal-oxygen bands in the prepared NC. The CS/FeO NC showed the potential bactericidal activity against E. coli, B. subtilis, and S. aureus pathogens. Further, CS/FeO NC also exhibited the dose-dependent anti-proliferative property against human lung cancer cells (A549). Thus, the obtained outcomes revealed that the prepared CS/FeO NC could be a promising candidate in the biomedical sector to inhibit the growth of bacterial pathogens and lung cancer cells

Isolation and Characterization of Bioremediation Potent Microorganisms from Spectrophotometrically Analysed Heavy Metal (Cr and Cd)-Rich Tannery Effluent

ABSTRACT Microorganisms can become tolerant and highly efficient in degrading toxic heavy metals that cause environmental pollution. This study focuses on the isolation of hexavalent Cr and Cd (II)-resistant bacteria collected from tannery effluents. The isolation was conducted by spread plate method on Agar plates supplemented with their respective heavy metal salts (K 2 Cr 2 O 7 and CdCl 2 ). A total of ten isolates were screened of which, two were subjected to 16sRNA sequencing on the basis of the degree of their resistance to heavy metals. The bacteria, identified from the isolates, were Flavobacterium psychrophilum and Flavobacterium sp. ARSA-103, which can be used for bioremediation of metal-contaminated effluents