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1,656 result(s) for "DNS"
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Genetics, crime and justice
As our understanding of genetics increases, its application to criminal justice becomes more significant. This timely book examines the use of genetic information both in criminal investigations and during the trial process. It discusses current scientific understanding and considers some potential legal, ethical and sociological issues with the use of genetic information. The author draws together debates from scientists, ethicists, sociologists and lawyers in order to understand how the criminal justice system currently reacts, and ought to react, to the new challenges presented by genetic evidence. She asks the important question of where priorities should lie: whether with society's desire to be protected from crime, or with an individual's desire to be protected from an unwanted intrusion into his or her genome. Topics include rights of privacy and consent in obtaining DNA samples, evidentiary issues in court, the impact of genetic evidence on punishment theory and sentencing, and genetic discrimination. This book will be of use to criminal and medical law students, along with academics, practitioners and policymakers interested in exploring the various criminal law issues in relation to genetics. It will also be of interest to criminal justice, philosophy, ethics, sociology and psychology students and academics looking explore the legal issues involved in such a topic.-- Source other than Library of Congress.
DNA sequence–directed shape change of photopatterned hydrogels via high-degree swelling
Shape-changing hydrogels that can bend, twist, or actuate in response to external stimuli are critical to soft robots, programmable matter, and smart medicine. Shape change in hydrogels has been induced by global cues, including temperature, light, or pH. Here we demonstrate that specific DNA molecules can induce 100-fold volumetric hydrogel expansion by successive extension of cross-links. We photopattern up to centimeter-sized gels containing multiple domains that undergo different shape changes in response to different DNA sequences. Experiments and simulations suggest a simple design rule for controlled shape change. Because DNA molecules can be coupled to molecular sensors, amplifiers, and logic circuits, this strategy introduces the possibility of building soft devices that respond to diverse biochemical inputs and autonomously implement chemical control programs.
Site-selective photoinduced cleavage and profiling of DNA by chiral semiconductor nanoparticles
Gene editing is an important genetic engineering technique that enables gene manipulation at the molecular level. It mainly relies on engineered nucleases of biological origin, whose precise functions cannot be replicated in any currently known abiotic artificial material. Here, we show that chiral cysteine-modified CdTe nanoparticles can specifically recognize and, following photonic excitation, cut at the restriction site GAT′ATC (′ indicates the cut site) in double-stranded DNA exceeding 90 base pairs, mimicking a restriction endonuclease. Although photoinduced reactive oxygen species are found to be responsible for the cleavage activity, the sequence selectivity arises from the affinity between cysteine and the conformation of the specific DNA sequence, as confirmed by quantum-chemical calculations. In addition, we demonstrate non-enzymatic sequence-specific DNA incision in living cells and in vivo using these CdTe nanoparticles, which may help in the design of abiotic materials for gene editing and other biological applications.
New CRISPR–Cas systems from uncultivated microbes
Using a metagenomic approach, three types of CRISPR–Cas systems have been discovered in uncultivated bacterial and archaeal hosts from a variety of different environments. CRISPR–Cas systems from uncultured microbes Current CRISPR–Cas technology is based on systems identified from cultured bacteria, whereas the enzymes from the numerous prokaryotes that have not been cultured have remained unexplored. By using cultivation-independent genome-resolved metagenomics, Jillian Banfield, Jennifer Doudna and colleagues identify and then functionally characterize new CRISPR–Cas systems. These include the first reported Cas9 in the archaeal domain of life, which was thought to lack such systems, as well as compact CRISPR–CasX and CRISPR–CasY systems. Genomic exploration of environmental microbial communities gives access to unprecedented genome diversity with the potential to revolutionize microbe-based biotechnologies. CRISPR–Cas systems provide microbes with adaptive immunity by employing short DNA sequences, termed spacers, that guide Cas proteins to cleave foreign DNA 1 , 2 . Class 2 CRISPR–Cas systems are streamlined versions, in which a single RNA-bound Cas protein recognizes and cleaves target sequences 3 , 4 . The programmable nature of these minimal systems has enabled researchers to repurpose them into a versatile technology that is broadly revolutionizing biological and clinical research 5 . However, current CRISPR–Cas technologies are based solely on systems from isolated bacteria, leaving the vast majority of enzymes from organisms that have not been cultured untapped. Metagenomics, the sequencing of DNA extracted directly from natural microbial communities, provides access to the genetic material of a huge array of uncultivated organisms 6 , 7 . Here, using genome-resolved metagenomics, we identify a number of CRISPR–Cas systems, including the first reported Cas9 in the archaeal domain of life, to our knowledge. This divergent Cas9 protein was found in little-studied nanoarchaea as part of an active CRISPR–Cas system. In bacteria, we discovered two previously unknown systems, CRISPR–CasX and CRISPR–CasY, which are among the most compact systems yet discovered. Notably, all required functional components were identified by metagenomics, enabling validation of robust in vivo RNA-guided DNA interference activity in Escherichia coli . Interrogation of environmental microbial communities combined with in vivo experiments allows us to access an unprecedented diversity of genomes, the content of which will expand the repertoire of microbe-based biotechnologies.
DNS Tunnelling, Exfiltration and Detection over Cloud Environments
The domain name system (DNS) protocol is fundamental to the operation of the internet, however, in recent years various methodologies have been developed that enable DNS attacks on organisations. In the last few years, the increased use of cloud services by organisations has created further security challenges as cyber criminals use numerous methodologies to exploit cloud services, configurations and the DNS protocol. In this paper, two different DNS tunnelling methods, Iodine and DNScat, have been conducted in the cloud environment (Google and AWS) and positive results of exfiltration have been achieved under different firewall configurations. Detection of malicious use of DNS protocol can be a challenge for organisations with limited cybersecurity support and expertise. In this study, various DNS tunnelling detection techniques were utilised in a cloud environment to create an effective monitoring system with a reliable detection rate, low implementation cost, and ease of use for organisations with limited detection capabilities. The Elastic stack (an open-source framework) was used to configure a DNS monitoring system and to analyse the collected DNS logs. Furthermore, payload and traffic analysis techniques were implemented to identify different tunnelling methods. This cloud-based monitoring system offers various detection techniques that can be used for monitoring DNS activities of any network especially accessible to small organisations. Moreover, the Elastic stack is open-source and it has no limitation with regards to the data that can be uploaded daily.
DNA-based programming of quantum dot valency, self-assembly and luminescence
The electronic and optical properties of colloidal quantum dots, including the wavelengths of light that they can absorb and emit, depend on the size of the quantum dots. These properties have been exploited in a number of applications including optical detection 1 , 2 , 3 , solar energy harvesting 4 , 5 and biological research 6 , 7 . Here, we report the self-assembly of quantum dot complexes using cadmium telluride nanocrystals capped with specific sequences of DNA. Quantum dots with between one and five DNA-based binding sites are synthesized and then used as building blocks to create a variety of rationally designed assemblies, including cross-shaped complexes containing three different types of dots. The structure of the complexes is confirmed with transmission electron microscopy, and photophysical studies are used to quantify energy transfer among the constituent components. Through changes in pH, the conformation of the complexes can also be reversibly switched, turning on and off the transfer of energy between the constituent quantum dots. Semiconductor nanocrystals capped with DNA can be used to make a variety of rationally designed assemblies with switchable optical properties.
Length-independent DNA packing into nanopore zero-mode waveguides for low-input DNA sequencing
Compared with conventional methods, single-molecule real-time (SMRT) DNA sequencing exhibits longer read lengths than conventional methods, less GC bias, and the ability to read DNA base modifications. However, reading DNA sequence from sub-nanogram quantities is impractical owing to inefficient delivery of DNA molecules into the confines of zero-mode waveguides—zeptolitre optical cavities in which DNA sequencing proceeds. Here, we show that the efficiency of voltage-induced DNA loading into waveguides equipped with nanopores at their floors is five orders of magnitude greater than existing methods. In addition, we find that DNA loading is nearly length-independent, unlike diffusive loading, which is biased towards shorter fragments. We demonstrate here loading and proof-of-principle four-colour sequence readout of a polymerase-bound 20,000-base-pair-long DNA template within seconds from a sub-nanogram input quantity, a step towards low-input DNA sequencing and mammalian epigenomic mapping of native DNA samples. Fast four-colour sequence readout from 20,000-bp-long DNA has been realized at sub-nanogram DNA input based on length-independent, voltage-induced DNA loading into waveguides equipped with nanopores in their floors.
DNS-BC: Fast, Reliable and Secure Domain Name System Caching System Based on a Consortium Blockchain
The Domain Name System (DNS) is a fundamental component of the internet, responsible for resolving domain names into IP addresses. DNS servers are typically categorized into four types: recursive resolvers, root name servers, Top-Level Domain (TLD) name servers, and authoritative name servers. The latter three types of servers store actual records, while recursive resolvers do not store any real data and are only responsible for querying the other three types of servers and responding to clients. Recursive resolvers typically maintain a caching system to speed up response times, but these caching systems have the drawbacks of a low real-time performance, a poor accuracy, and many security and privacy issues. In this paper, we propose a caching system based on a consortium blockchain, namely DNS-BC, which uses the synchronization mechanism of the consortium blockchain to achieve a high real-time performance, uses the immutable mechanism of the consortium blockchain and our designed credibility management system to achieve up to a 100% accuracy, and has been combined with encrypted transmission protocols to solve common security and privacy issues. At the same time, this caching system can greatly reduce the traffic that name servers need to handle, thereby protecting them from Denial-of-Service (DoS) attacks. To further accelerate the data transmission speed, we have designed a new encrypted DNS protocol called DNS over KCP (DoK). The DoK protocol is based on the KCP protocol, which is a fast and reliable transmission protocol, and its latency can reach one-third of that of TCP when the network environment deteriorates. In our experiments, the transmission time of this protocol is about a quarter of that of the widely used encrypted protocols DNS over TLS (DoT) and DNS over HTTPS (DoH).
A Lightweight Double-Stage Scheme to Identify Malicious DNS over HTTPS Traffic Using a Hybrid Learning Approach
The Domain Name System (DNS) protocol essentially translates domain names to IP addresses, enabling browsers to load and utilize Internet resources. Despite its major role, DNS is vulnerable to various security loopholes that attackers have continually abused. Therefore, delivering secure DNS traffic has become challenging since attackers use advanced and fast malicious information-stealing approaches. To overcome DNS vulnerabilities, the DNS over HTTPS (DoH) protocol was introduced to improve the security of the DNS protocol by encrypting the DNS traffic and communicating it over a covert network channel. This paper proposes a lightweight, double-stage scheme to identify malicious DoH traffic using a hybrid learning approach. The system comprises two layers. At the first layer, the traffic is examined using random fine trees (RF) and identified as DoH traffic or non-DoH traffic. At the second layer, the DoH traffic is further investigated using Adaboost trees (ADT) and identified as benign DoH or malicious DoH. Specifically, the proposed system is lightweight since it works with the least number of features (using only six out of thirty-three features) selected using principal component analysis (PCA) and minimizes the number of samples produced using a random under-sampling (RUS) approach. The experiential evaluation reported a high-performance system with a predictive accuracy of 99.4% and 100% and a predictive overhead of 0.83 µs and 2.27 µs for layer one and layer two, respectively. Hence, the reported results are superior and surpass existing models, given that our proposed model uses only 18% of the feature set and 17% of the sample set, distributed in balanced classes.
A mechanical metamaterial made from a DNA hydrogel
Metamaterials are artificial substances that are structurally engineered to have properties not typically found in nature. To date, almost all metamaterials have been made from inorganic materials such as silicon and copper 1 , 2 , which have unusual electromagnetic or acoustic properties 1 , 2 , 3 , 4 , 5 that allow them to be used, for example, as invisible cloaks 6 , 7 , 8 , 9 , superlenses 10 , 11 , 12 or super absorbers for sound 13 . Here, we show that metamaterials with unusual mechanical properties can be prepared using DNA as a building block. We used a polymerase enzyme to elongate DNA chains and weave them non-covalently into a hydrogel. The resulting material, which we term a meta-hydrogel, has liquid-like properties when taken out of water and solid-like properties when in water. Moreover, upon the addition of water, and after complete deformation, the hydrogel can be made to return to its original shape. The meta-hydrogel has a hierarchical internal structure and, as an example of its potential applications, we use it to create an electric circuit that uses water as a switch. Mechanical metamaterials that have liquid-like properties when taken out of water and solid-like properties when in water can be prepared from DNA hydrogels.