Asynchronous Gathering of Robots with Finite Memory on a Circle under Limited Visibility

Consider a set of $n$ mobile entities, called robots, located and operating on a continuous circle, i.e., all robots are initially in distinct locations on a circle. The \textit{gathering} problem asks to design a distributed algorithm that allows the robots to assemble at a point on the circle. Robots are anonymous, identical, and homogeneous. Robots operate in a deterministic Look-Compute-Move cycle within the circular path. Robots agree on the clockwise direction. The robot's movement is rigid and they have limited visibility $\pi$, i.e., each robot can only see the points of the circle which is at an angular distance strictly less than $\pi$ from the robot. Di Luna \textit{et al}. [DISC'2020] provided a deterministic gathering algorithm of oblivious and silent robots on a circle in semi-synchronous (\textsc{SSync}) scheduler. Buchin \textit{et al}. [IPDPS(W)'2021] showed that, under full visibility, $\mathcal{OBLOT}$ robot model with \textsc{SSync} scheduler is incomparable to $\mathcal{FSTA}$ robot (robots are silent but have finite persistent memory) model with asynchronous (\textsc{ASync}) scheduler. Under limited visibility, this comparison is still unanswered. So, this work extends the work of Di Luna \textit{et al}. [DISC'2020] under \textsc{ASync} scheduler for $\mathcal{FSTA}$ robot model

USABILITY OF E-RESOURCES AMONG LIBRARY & INFORMATION SCIENCE STUDENTS IN PATNA, BIHAR: A STUDY

The research aims into library science students at Patna University in Bihar\u27s understanding and use of electronic resources and many other relevant topics. In this investigation, the researcher adopted a descriptive strategy. The main objective of the paper is to get an understanding of the use of electronic resources by the library user. Overall, 90 questionnaires were distributed, whereas only 72 were filled and returned as a sample. To collect data from the users, a systematic questionnaire was constructed. The study aimed to determine the users\u27 requirements and level of consciousness and use of electronic resources. According to data, many users were satisfied with infrastructure facilities, required information, or other reasons for using e-resources and services. However, some users could not use the e-resources due to the lack of user education and awareness campaigns, language difficulties, and IT skills and understanding. As a result, libraries should actively launch well-planned user awareness and education initiatives, expand infrastructure, and subscribe to more e-resources

Role of saline infusion sonography in evaluation of abnormal uterine bleeding

Background: Abnormal uterine bleeding (AUB) is one of the most common reasons for women seeking gynaecological advice. The objective of this study was to determine the accuracy of Transvaginal sonography (TVS) and Saline Infusion Sonography (SIS) in evaluation of Abnormal Uterine Bleeding (AUB) and to compare the diagnostic accuracy after hysterectomy.Methods: Prospective, comparative study of TVS and SIS in evaluation of AUB in patients who are being subjected to hysterectomy with uterus of less than 12 weeks.Results: 100 patients were included in the study. 98% were of 30-50 years. Heavy menstrual bleeding was the commonest symptom (52%) and most common finding was fibroid, and Polyp followed by abnormal endometrium. The overall sensitivity and specificity when correlated with operative and HPE were 66% and 88% respectively for TVS and 82% and 95% for SIS respectively. The false positive and false negative rates were more in TVS compared to SIS. Commonest histopathology was intramural fibroid in 42% followed by sub mucus myoma in 21%, polyp 18% and endometrial hyperplasia 10%.Conclusions: SIS is a simple highly sensitive and specific technique to detect intra uterine pathology in the evaluation of AUB when TVS findings are inconclusive

A Review of Second Generation of Terrestrial Digital Video Broadcasting System

Digital broadcast systems have increasingly been deployed for various services such as Digital Video Broadcasting (i.e. DVB-S, DVB-T, etc.) and Digital Audio Broadcasting (DAB). Classical digital broadcast systems were designed with fixed modulation guarantee reliable communication even with very hostile channel environment.  DVB-T2 terrestrial television standard is becoming increasingly important.  The emergence of it is motivated by the higher spectral efficiency and adopting  transition from analogue TV to DVB-T2, or transition from DVB-T to DVB-T2. It can reduce the transmission cost per program and deliver HD services economically viable. It introduces a new technique to improve performance in channels with frequency selective fading. If in addition improved source coding (MPEG-4) is employed, the gain in broadcast transmission is remarkable.   Keywords: DVB-T, DVB-T2, Digital video broadcastin

Rendezvous on a Known Dynamic Point on a Finite Unoriented Grid

In this paper, we have considered two fully synchronous $\mathcal{OBLOT}$ robots having no agreement on coordinates entering a finite unoriented grid through a door vertex at a corner, one by one. There is a resource that can move around the grid synchronously with the robots until it gets co-located along with at least one robot. Assuming the robots can see and identify the resource, we consider the problem where the robots must meet at the location of this dynamic resource within finite rounds. We name this problem "Rendezvous on a Known Dynamic Point". Here, we have provided an algorithm for the two robots to gather at the location of the dynamic resource. We have also provided a lower bound on time for this problem and showed that with certain assumption on the waiting time of the resource on a single vertex, the algorithm provided is time optimal. We have also shown that it is impossible to solve this problem if the scheduler considered is semi-synchronous

Space and move-optimal Arbitrary Pattern Formation on infinite rectangular grid by Oblivious Robot Swarm

Arbitrary Pattern Formation (APF) is a fundamental coordination problem in swarm robotics. It requires a set of autonomous robots (mobile computing units) to form any arbitrary pattern (given as input) starting from any initial pattern. The APF problem is well-studied in both continuous and discrete settings. This work concerns the discrete version of the problem. A set of robots is placed on the nodes of an infinite rectangular grid graph embedded in a euclidean plane. The movements of the robots are restricted to one of the four neighboring grid nodes from its current position. The robots are autonomous, anonymous, identical, and homogeneous, and operate Look-Compute-Move cycles. Here we have considered the classical $\mathcal{OBLOT}$ robot model, i.e., the robots have no persistent memory and no explicit means of communication. The robots have full unobstructed visibility. This work proposes an algorithm that solves the APF problem in a fully asynchronous scheduler under this setting assuming the initial configuration is asymmetric. The considered performance measures of the algorithm are space and number of moves required for the robots. The algorithm is asymptotically move-optimal. A definition of the space-complexity is presented here. We observe an obvious lower bound $\mathcal{D}$ of the space complexity and show that the proposed algorithm has the space complexity $\mathcal{D}+4$. On comparing with previous related works, we show that this is the first proposed algorithm considering $\mathcal{OBLOT}$ robot model that is asymptotically move-optimal and has the least space complexity which is almost optimal

Circle Formation by Asynchronous Opaque Fat Robots on an Infinite Grid

This study addresses the problem of "Circle Formation on an Infinite Grid by Fat Robots" ($CF\_FAT\_GRID$). Unlike prior work focused solely on point robots in discrete domain, it introduces fat robots to circle formation on an infinite grid, aligning with practicality as even small robots inherently possess dimensions. The algorithm, named $CIRCLE\_FG$, resolves the $CF\_FAT\_GRID$ problem using a swarm of fat luminous robots. Operating under an asynchronous scheduler, it achieves this with five distinct colors and by leveraging one-axis agreement among the robots

Room-Temperature Anomalous Hall Effect in Graphene in Interfacial Magnetic Proximity with EuO Grown by Topotactic Reduction

We show that thin layers of EuO, a ferromagnetic insulator, can be achieved by topotactic reduction under titanium of a Eu2O3 film deposited on top of a graphene template. The reduction process leads to the formation of a 7-nm thick EuO smooth layer, without noticeable structural changes in the underlying chemical vapor deposited (CVD) graphene. The obtained EuO films exhibit ferromagnetism, with a Curie temperature that decreases with the initially deposited Eu2O3 layer thickness. By adjusting the thickness of the Eu2O3 layer below 7 nm, we promote the formation of EuO at the very graphene interface: the EuO/graphene heterostructure demonstrates the anomalous Hall effect (AHE), which is a fingerprint of proximity-induced spin polarization in graphene. The AHE signal moreover persists above Tc up to 350K due to a robust super-paramagnetic phase in EuO. This original high-temperature magnetic phase is attributed to magnetic polarons in EuO: we propose that the high strain in our EuO films grown on graphene stabilizes the magnetic polarons up to room temperature. This effect is different from the case of bulk EuO in which polarons vanish in the vicinity of the Curie temperature Tc= 69K.Comment: 29 page

Time Optimal Gathering of Robots on an Infinite Triangular Grid with Limited Visibility

This work deals with the problem of gathering of $n$ oblivious mobile entities, called robots, with limited visibility, at a point (not known beforehand) placed on an infinite triangular grid. Earlier works of gathering mostly considered the robots either on a plane or on a circle or on a rectangular grid under both full and limited visibility. In the triangular grid, there are two works to the best of our knowledge. The first one is arbitrary pattern formation where full visibility is considered (\cite{C21}). The other one considers seven robots with 2- hop visibility that form a hexagon with one robot in the center of the hexagon in a collision-less environment under a fully synchronous scheduler (\cite{ShibataOS00K21}). In this work, we first show that gathering on a triangular grid with 1-hop vision of robots is not possible even under a fully synchronous scheduler if the robots do not agree on any axis. So one axis agreement has been considered in this work (i.e., the robots agree on a direction and its orientation). We have also showed that the lower bound for time is $\Omega(n)$ epochs when $n$ number of robots are gathering on an infinite triangular grid. An algorithm is then presented where a swarm of $n$ number of robots with 1-hop visibility can gather within $O(n)$ epochs under a semi-synchronous scheduler. So the algorithm presented here is time optimal