Comunicação de dados baseada no escalonamento de trabalho de nós vizinhos em redes de sensores sem fio

The best way to save energy in Wireless Sensor Networks (WSNs) is to have sensor nodes go to sleep whenever possible, making them periodically unavailable. On the other hand, this unavailability may affect network tasks such as data communication. Media Access Control protocols for these networks typically deal with the problem of scheduling the data communication when the next hop is sleeping. One of the approaches used by those protocols (proactive policy) is to share each node's working schedule with its neighbors and have sender nodes to schedule their transmissions to their next hop awaking moment. This sharing process is typically based on message exchanges, which increases the network energy consumption. Another approach (reactive policy) is to discover when the next hop is going to be awake, and, have a node to send a message at that moment. Although this approach eliminates the sharing cost, its discovery process introduces additional packet transmissions as well. Given the limitations of both polices, this thesis proposes three solutions to eliminate or minimize the sharing and discovery costs of a node's schedule. The first is a hybrid policy that combines both existing approaches. In this case, each sender node inserts its working schedule into its packet and each receiver node saves this information to use in future transmissions. The second contribution is a combined design involving the reactive policy and the receiver-based routing. This routing technique increases the number of next hop candidates and can minimize the cost of the reactive discovery. In this combined design, a sender node has to discover the working schedule of some neighbor node instead of a specific neighbor. Our last contribution is the Gossiping Using the Energy Map (GEM) protocol, a cross-layer design solution involving the network and MAC layers to perform broadcasting when sensor nodes frequently sleep (e.g., during 99% of their lifetime). In this case, when a sender node sends a packet, not all neighbors will be awake. Most of the solutions proposed for broadcasting in WSNs ignore that sensor nodes can frequently sleep. The main idea of this protocol is to create a broadcasting tree based on the network energy map (the information about the amount of energy available at each part of the network) and make each sensor node share information with only one neighbor node that belongs to this tree. Furthermore, this protocol explores the energy map to change the basic operation of nodes localized inside low-energy regions. Simulation results reveal that our solutions reduce the number of transmissions and energy consumption when compared with other solutions proposed in the literature and evaluated in this work.A melhor forma de economizar energia em Redes de Snsores Sem Fio (RSSFs) é fazer com que os nós sensores adormeçam sempre que possível, fazendo com que eles fiquem indisponíveis periodicamente. No entanto, essa indisponibilidade oide afetar tarefas de rede como a comunicação de dados. Protocolos para controle de acesso ao meio para essas redes tipicamente tratam o problema de escalonar a comunicação de dados quando o próximo nó estiver dormindo. Uma das abordagens usadas por esses protocolos (política pró-ativa) é compartilhar seu escalonamento de trabalho com seus vizinhos e cada nó emissor agenda sua transmissão para o momento em que o próximo nó estiver acordado. Esse processo de compartilhamento é tipicamente baseado em troca de pacotes, o que aumenta o consumo de energia da rede. Outra abordagem (política reativa) é descobrir quando o próximo nó estará acordado e, depois, enviar o pacote nesse momento. Apesar dessa abordagem eliminar o custo de compartilhamento, suas descobertas também efetuam transmissões adicionais. Dadas as limitações das duas abordagens, esta tese propõe três soluções para minimizar os custos de compartilhamento e descoberta. A primeira solução é uma abordagem híbrida entre as duas políticas existentes. Nesse caso, cada nó emissor insere seu escalonamento de trabalho em sua mensagem e cada receptor guarda essa informação para usá-la em transmissões futuras. A segunda solução é um projeto combinado entre a política reativa e o roteamento baseado no receptor. Essa abordagem de roteamento aumenta o número de candidatos a próximo nó, o que minimiza o custo de energia da descoberta reativa. Nesse projeto combinado, o nó emissor tem que descobrir o escalonamento de um nó específico. A última solução é o protocolo Gossiping Using the Energy Map (GEM), um projeto integrado envolvendo as camadas de rede e MAC para efetuar difusão de dados quando os nós sensores ficam quase sempre dormindo (por exemplo, durante 99% de seus tempos de vida). Nesse caso, quando um nó emissor envia um pacote, nem todos seus vizinhos estarão acordados. A maioria das soluções propostas para difusão de dadosem RSSFs desconsidera que os nós sensores podem ficar frequentemente dormindo. A ideia principal do GEM é criar uma árvore de difusão baseada no mapa de energia da rede (informação sobre a energia restante em cada parte da rede) e fazer com que cada nó sensor compartilhe informações apenas com um nó vizinho que participa dessa árvore disseminando dados. Além disso, o GEM usa o mapa de energia para adaptar o funcionamento básico dos nós localizados dentro de regiões de baixa energia, prolongando o tempo de vida da rede. Resultados de simulação mostram que as soluções propostas nesta tese reduzem a quantidade de transmissões e consomem menos energia quando comparadas com outras soluções propostas na literatura e avaliadas neste trabalho

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Structure-Guided Redesign Improves NFL HIV Env Trimer Integrity and Identifies an Inter-Protomer Disulfide Permitting Post-Expression Cleavage

Soluble HIV-1 envelope glycoprotein (Env) trimers are under active investigation as vaccine candidates in relevant pre-clinical models. Like SOSIPs, the cleavage-independent native flexibly linked (NFL) trimers are faithful mimics of the Env spike. Here, we analyzed multiple new designs to explore alternative modifications, informing tertiary interactions, while maintaining NFL trimer homogeneity and integrity. Accordingly, we performed a proline (P) substitution screen in the gp41 heptad repeat 1 region, identifying other trimer-enhancing Ps, including L555P. This P improved trimer integrity compared to I559P in selected properties. Next, we screened 15 structure-guided potential cysteine pairs in gp140 and found that A501C-L663C (“CC2”) forms an inter-protomer disulfide bond that demonstrably increased NFL trimer thermostability. We combined these two approaches with trimer-derived substitutions, coupled with glycine substitutions at helix-to-coil transitions, developed by our group. To increase the exposure of the fusion peptide (FP) N-terminus, we engineered an enterokinase (EK) cleavage site upstream of the FP for controlled post-expression cleavage. In combination, the redesigns resulted in highly stable and homogeneous NFL mimics derived from different clades. Following recombinant EK cleavage, the NFL trimers retained covalent linkage, maintaining a native-like structure while displaying enhanced stability and favorable antigenic features. These trimers also displayed increased exposure of neutralizing epitopes in the FP and gp120/gp41 interface, while retaining other neutralizing epitopes and occluding non-neutralizing elements. This array of Env-structure-guided designs reveals additional interactive regions in the prefusion state of the HIV Env spike, affording the development of novel antigens and immunogens

Uphold the nuclear weapons test moratorium

The Trump administration is considering renewing nuclear weapons testing (1), a move that could increase the risk of another nuclear arms race as well as an inadvertent or intentional nuclear war. Following in the long tradition of scientists opposing nuclear weapons due to their harmful effects on both humanity and the planet (2), we ask the U.S. government to desist from plans to conduct nuclear tests. During the Cold War, the United States conducted 1030 nuclear weapons tests, more than all other nuclear-armed nations combined (3). In 1996, the United States signed the Comprehensive Nuclear Test Ban Treaty (CTBT), agreeing not to conduct a nuclear weapons test of any yield (4). The United States has not yet ratified the CTBT but did spearhead the 2016 adoption of UN Security Council Resolution 2310, which calls upon all countries to uphold the object and purpose of the CTBT by not conducting nuclear tests (5). Eight of the nine nuclear-armed states, including the five permanent members of the UN Security Council, have observed a moratorium on nuclear testing since 1998 (3, 4). The ninth, North Korea, responding to international pressure, stopped testing warhead detonations (as opposed to missile flights) in 2017 (6). If the United States ratified the CTBT, joining the 168 countries who have already done so (4), there is a good chance that the other holdout countries would ratify the treaty as well (7)

Uphold the nuclear weapons test moratorium

The Trump administration is considering renewing nuclear weapons testing (1), a move that could increase the risk of another nuclear arms race as well as an inadvertent or intentional nuclear war. Following in the long tradition of scientists opposing nuclear weapons due to their harmful effects on both humanity and the planet (2), we ask the U.S. government to desist from plans to conduct nuclear tests. During the Cold War, the United States conducted 1030 nuclear weapons tests, more than all other nuclear-armed nations combined (3). In 1996, the United States signed the Comprehensive Nuclear Test Ban Treaty (CTBT), agreeing not to conduct a nuclear weapons test of any yield (4). The United States has not yet ratified the CTBT but did spearhead the 2016 adoption of UN Security Council Resolution 2310, which calls upon all countries to uphold the object and purpose of the CTBT by not conducting nuclear tests (5). Eight of the nine nuclear-armed states, including the five permanent members of the UN Security Council, have observed a moratorium on nuclear testing since 1998 (3, 4). The ninth, North Korea, responding to international pressure, stopped testing warhead detonations (as opposed to missile flights) in 2017 (6). If the United States ratified the CTBT, joining the 168 countries who have already done so (4), there is a good chance that the other holdout countries would ratify the treaty as well (7)

An international effort towards developing standards for best practices in analysis, interpretation and reporting of clinical genome sequencing results in the CLARITY Challenge

There is tremendous potential for genome sequencing to improve clinical diagnosis and care once it becomes routinely accessible, but this will require formalizing research methods into clinical best practices in the areas of sequence data generation, analysis, interpretation and reporting. The CLARITY Challenge was designed to spur convergence in methods for diagnosing genetic disease starting from clinical case history and genome sequencing data. DNA samples were obtained from three families with heritable genetic disorders and genomic sequence data were donated by sequencing platform vendors. The challenge was to analyze and interpret these data with the goals of identifying disease-causing variants and reporting the findings in a clinically useful format. Participating contestant groups were solicited broadly, and an independent panel of judges evaluated their performance. RESULTS: A total of 30 international groups were engaged. The entries reveal a general convergence of practices on most elements of the analysis and interpretation process. However, even given this commonality of approach, only two groups identified the consensus candidate variants in all disease cases, demonstrating a need for consistent fine-tuning of the generally accepted methods. There was greater diversity of the final clinical report content and in the patient consenting process, demonstrating that these areas require additional exploration and standardization. CONCLUSIONS: The CLARITY Challenge provides a comprehensive assessment of current practices for using genome sequencing to diagnose and report genetic diseases. There is remarkable convergence in bioinformatic techniques, but medical interpretation and reporting are areas that require further development by many groups

Observation of γγ → ττ in proton-proton collisions and limits on the anomalous electromagnetic moments of the τ lepton

The production of a pair of τ leptons via photon–photon fusion, γγ → ττ, is observed for the f irst time in proton–proton collisions, with a significance of 5.3 standard deviations. This observation is based on a data set recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb−1. Events with a pair of τ leptons produced via photon–photon fusion are selected by requiring them to be back-to-back in the azimuthal direction and to have a minimum number of charged hadrons associated with their production vertex. The τ leptons are reconstructed in their leptonic and hadronic decay modes. The measured fiducial cross section of γγ → ττ is σfid obs = 12.4+3.8 −3.1 fb. Constraints are set on the contributions to the anomalous magnetic moment (aτ) and electric dipole moments (dτ) of the τ lepton originating from potential effects of new physics on the γττ vertex: aτ = 0.0009+0.0032 −0.0031 and |dτ| < 2.9×10−17ecm (95% confidence level), consistent with the standard model

Predation on Live and Artificial Insect Prey Shows Different Global Latitudinal Patterns

AimLong-standing theory predicts that the intensity of biotic interactions increases from high to low latitudes. Studies addressing geographic variation in predation on insect prey have often relied on prey models, which lack many characteristics of live prey. Our goals were to explore global latitudinal patterns of predator attack rates on standardised live insect prey and to compare the patterns in predation on live insects with those on plasticine prey models.LocationGlobal forested areas.Time Period2021–2023.Major TaxaArthropods, birds.MethodsWe measured predation rates in 43 forested locations distributed across five continents from 34.1° S to 69.5° N latitude. At each location, we exposed 20 sets of three bait types, one set per tree. Each set included three live fly larvae (maggots), three live fly puparia and three plasticine models of the puparia. We used glue rings to isolate half of the sets from non-flying predators.ResultsArthropod attack rates on plasticine prey decreased linearly from low to high latitudes, whereas attack rates on maggots had a U shaped distribution, with the lowest predation rates at temperate latitudes and the highest rates at tropical and boreal latitudes. This difference emerged from intensive predator attacks on live maggots, but not on plasticine models, in boreal sites. Site-specific attack rates of arthropod predators on live and plasticine prey were not correlated. In contrast, bird attack rates on live maggots and plasticine models were positively correlated, but did not show significant latitudinal changes.Main ConclusionsLatitudinal patterns in predation differ between major groups of predators and between types of prey. Poleward decreases in both arthropod and combined arthropod and bird predation on plasticine models do not mirror patterns of predation on our live prey, the latter likely reflecting real patterns of predation risk better than do patterns of attack on artificial prey