The size of the immune repertoire of bacteria

Some bacteria and archaea possess an immune system, based on the CRISPR-Cas mechanism, that confers adaptive immunity against phage. In such species, individual bacteria maintain a "cassette" of viral DNA elements called spacers as a memory of past infections. The typical cassette contains a few dozen spacers. Given that bacteria can have very large genomes, and since having more spacers should confer a better memory, it is puzzling that so little genetic space would be devoted by bacteria to their adaptive immune system. Here, we identify a fundamental trade-off between the size of the bacterial immune repertoire and effectiveness of response to a given threat, and show how this tradeoff imposes a limit on the optimal size of the CRISPR cassette.Comment: 9 pages, 5 figure

Application of Cognitivе Radio in Smart Grid Communication

Wireless communication is fast becoming the most common mode of communication. Invention of Bluetooth, WI-Fi, WiMAX, etc. have aided in popularizing wireless communication. Now wireless communication is being sought at for achieving communication in smart grid network .In a conventional power distribution system the power which was generated was being transmitted through the transmission link without taking into account the demand of the user. In a smart grid we address that issue. There is a flow of information from both sides. There are devices communicating with each other in sharing information. Advanced mitring scheme, dynamic pricing scheme have become new paradigm in smart grid. Research is going on for application of cognitive radios in smart grid communication .The spectrum used for communication is limited. Out of the channels available some have been licensed to certain users who are known as primary users. The other users are known as secondary users. The secondary users are large in number and the frequency channels available for them to communicate is limited in number. But the primary user use their allotted channels for very small amount of time. So, the secondary users can tap into those frequencies whenever it is idle. This can achieve efficiency in communication and help in reducing communication blockage of secondary users. Cognitive radios help in sensing the availability of the primary users in a channel and relay the data to secondary users so that they could use them. They also perform the task of switching the secondary users into another channel whenever a primary user uses that channel. In my work I have tried to find out an effective dynamic traffic scheduling scheme for effective communication purposes. First I had taken a scheme in which priority levels were assigned to different groups of secondary users without considering QoS of the channels. In my work I have tried to find out an еffеctivе dynamic traffic scheduling scheme for еffеctivе communication purposes. First I had taken a scheme in which priority levels wеrе assigned to different groups of secondary users without considering QoS of the channels. Thеn wе took QoS into consideration and calculated the system utilization, blocking probability in both cases for diffеrеnt sеcondary usеrs. Finally, I calculated the end to end delay using an optimal algorithm and comparеd it with thе еnd to еnd dеlay calculatеd without thе algorithm

Mechanisms of blood homeostasis: lineage tracking and a neutral model of cell populations in rhesus macaques.

BACKGROUND:How a potentially diverse population of hematopoietic stem cells (HSCs) differentiates and proliferates to supply more than 10(11) mature blood cells every day in humans remains a key biological question. We investigated this process by quantitatively analyzing the clonal structure of peripheral blood that is generated by a population of transplanted lentivirus-marked HSCs in myeloablated rhesus macaques. Each transplanted HSC generates a clonal lineage of cells in the peripheral blood that is then detected and quantified through deep sequencing of the viral vector integration sites (VIS) common within each lineage. This approach allowed us to observe, over a period of 4-12 years, hundreds of distinct clonal lineages. RESULTS:While the distinct clone sizes varied by three orders of magnitude, we found that collectively, they form a steady-state clone size-distribution with a distinctive shape. Steady-state solutions of our model show that the predicted clone size-distribution is sensitive to only two combinations of parameters. By fitting the measured clone size-distributions to our mechanistic model, we estimate both the effective HSC differentiation rate and the number of active HSCs. CONCLUSIONS:Our concise mathematical model shows how slow HSC differentiation followed by fast progenitor growth can be responsible for the observed broad clone size-distribution. Although all cells are assumed to be statistically identical, analogous to a neutral theory for the different clone lineages, our mathematical approach captures the intrinsic variability in the times to HSC differentiation after transplantation

Ragam Basa Pacaturan Antarane Penyiar Lan Pamidhanget Radhio Pro 4 RRI Surabaya Ing Adicara“Mandhing Jamuran”

Ragam basa maujud amarga anane babagan sosial, kultur, lan konteks kang beda. Panliten iki njupukobjek Radhio Pro 4 RRI Surabaya lan punjere panliten luwih mligi marang wujud ragam basa adhedhasarpanutur.Dhasar panliten iki yaiku ngenani ragam basa. Kalebu idiolek, akrolek, basilek, lan kolokial. Undheranepanliten iki yaiku kepriye wujud ragam basa lan kepriye undha-usuking basa sajrone pacaturan antaranepenyiar lan pamidhanget radhio Pro 4 RRI Surabaya. Ancase panliten iki yaiku ngandharake kepriye wujudragam basa lan kepriye undha-usuking basa sajrone pacaturan antarane penyiar lan pamidhanget radhio Pro 4RRI Surabaya. Paedah teoretis panliten iki yaiku bisa menehi sumbangsih marang panliten ngenanipanganggone basa. Paedah praktise supaya bisa migunani tumrap pasinaon Sosiolinguistik.Panliten iki minangka panliten Sosiolinguistik awit ngrembug basa sing ana sesambungane karokahanan sosial sajrone bebrayan. Panliten iki asipat deskriptif. Teori sing digunakake yaiku teori SosiolinguistikChaer. Metodhe sing digunakake yaiku metodhe deskriptif kualitatif. Dhata panliten iki dijupuk dening panlitiing lapangan. Sumber dhata panliten iki yaiku pacaturan sing ditindakake dening penyiar lan pamidhangetradhio Pro 4 RRI Surabaya.Panliten iki mung ngrembug saperangan wujud ragam basa lan wujud undha-usuk basa sajronepacaturan antarane penyiar lan pamidhanget radhio pro 4 RRI Surabaya ing adicara Mandhing Jamuran.Ragam basa sajrone pacaturan antarane penyiar lan pamidhanget radhio Pro 4 RRI Surabaya kaperang dadipapat yaiku idiolek, akrolek, basilek, lan kolokial. Dene wujud undha-usuke basa sajrone pacaturan antaranepenyiar lan pamidhanget radhio Pro 4 RRI Surabaya kaperang dadi telu yaiku wujud krama-ngoko, kramamadya, lan krama-Indhonesia.Tembung wigati: Ragam Basa, Penyiar lan Pamidhanget, Radhio Pro 4 RRI

A quantitative comparison of sRNA-based and protein-based gene regulation

Small, non-coding RNAs (sRNAs) play important roles as genetic regulators in prokaryotes. sRNAs act post-transcriptionally via complementary pairing with target mRNAs to regulate protein expression. We use a quantitative approach to compare and contrast sRNAs with conventional transcription factors (TFs) to better understand the advantages of each form of regulation. In particular, we calculate the steady-state behavior, noise properties, frequency-dependent gain (amplification), and dynamical response to large input signals of both forms of regulation. While the mean steady-state behavior of sRNA-regulated proteins exhibits a distinctive tunable threshold-linear behavior, our analysis shows that transcriptional bursting leads to significantly higher intrinsic noise in sRNA-based regulation than in TF-based regulation in a large range of expression levels and limits the ability of sRNAs to perform quantitative signaling. Nonetheless, we find that sRNAs are better than TFs at filtering noise in input signals. Additionally, we find that sRNAs allow cells to respond rapidly to large changes in input signals. These features suggest a niche for sRNAs in allowing cells to transition quickly yet reliably between distinct states. This functional niche is consistent with the widespread appearance of sRNAs in stress-response and quasi-developmental networks in prokaryotes.Comment: 26 pages, 8 figures; accepted for publication in Molecular Systems Biolog

Information processing and signal integration in bacterial quorum sensing

Bacteria communicate using secreted chemical signaling molecules called autoinducers in a process known as quorum sensing. The quorum-sensing network of the marine bacterium {\it Vibrio harveyi} employs three autoinducers, each known to encode distinct ecological information. Yet how cells integrate and interpret the information contained within the three autoinducer signals remains a mystery. Here, we develop a new framework for analyzing signal integration based on Information Theory and use it to analyze quorum sensing in {\it V. harveyi}. We quantify how much the cells can learn about individual autoinducers and explain the experimentally observed input-output relation of the {\it V. harveyi} quorum-sensing circuit. Our results suggest that the need to limit interference between input signals places strong constraints on the architecture of bacterial signal-integration networks, and that bacteria likely have evolved active strategies for minimizing this interference. Here we analyze two such strategies: manipulation of autoinducer production and feedback on receptor number ratios.Comment: Supporting information is in appendi

Domain walls between gaugings in Maximal Supergravity

openIn this thesis, we explore domain wall solutions that interpolate between different gauge coupling values within a class of gauged maximal supergravity theories in four dimensions. We begin with a review of supergravity, superstring theories, and their interrelations. Following this, we discuss the gauging of supergravity using the embedding tensor formalism. We also outline the procedure of toroidal compactifications and briefly examine the connections between fluxes and gaugings. As an introductory step, we revisit the role of Romans' mass in ten-dimensional Type IIA massive supergravity and derive specific 1/2 BPS 8-brane solutions by solving the Killing spinor equations. In these solutions, Romans' mass behaves as a locally constant function, contributing to a discontinuity in the derivative of the harmonic function. We then reinterpret this computation within the framework of a particular gauging of four-dimensional maximal supergravity. Lastly, we extend our analysis by constructing a broader set of domain wall solutions linked to a family of CSO(p,q,r) gaugings, where different subsets of gauge couplings experience discontinuities across the domain wall