Denial of Service (DoS) attacks constitute a major security threat to today’s Internet. This challenge is especially pertinent to the Internet of Things (IoT) as devices have less computing power, memory and security mechanisms to mitigate DoS attacks. This paper presents a model that mimics the unique characteristics of a network of IoT devices, including components of the system implementing ...

A denial-of-service attack (DoS attack) is an attempt to make a system resource unavailable to its intended users. Several types of DoS attacks are known. A SYN flood attack is a typical DoS attack, exploiting the vulnerability of TCP’s three-way handshake with respect to imbalances between the computational costs of clients and server. In addition to cost imbalance, the amount of cost over a g...

Client puzzles are meant to act as a defense against denial of service (DoS) attacks by requiring a client to solve some moderately hard problem before being granted access to a resource. However, recent client puzzle difficulty definitions (Stebila and Ustaoglu, 2009; Chen et al., 2009) do not ensure that solving n puzzles is n times harder than solving one puzzle. Motivated by examples of puz...

Resumo. Neste artigo é analisada a influência dos parâmetros de aprendizagem de algoritmos baseados em enxames e propostas estratégias para a atualização de políticas em ambientes dinâmicos. Nós verificamos que os parâmetros de aprendizagem quando ajustados inadequadamente podem ocasionar atrasos no processo de aprendizagem ou convergir para uma política não-satisfatória. Além disso, esse probl...

A assistência da deslocalização de elétrons sigma ou assistência anquimérica dos elétrons sigma explica grandes diferenças de velocidade na solvólise de 2-exoe 2-endo-norbornilp-bromobenzenosulfonatos. Este estudo foi anteriormente analisado pela teoria dos orbitais moleculares em fase gás. Ao revisitar este antigo problema a partir da teoria quântica de átomos em moléculas (QTAIM), novas infor...

Introdução e objetivo: A Doença Inl amatória Intestinal (DII) em 25-30% dos casos manifesta-se em idade pediátrica, reconhecendose um aumento da incidência nos últimos anos, particularmente de Doença de Cronh (DC). Pretendeu-se caracterizar o peri l clínico dos casos de DII em seguimento numa Unidade de Gastrenterologia Pediátrica, num período de 11 anos. Material e métodos: Estudo retrospectiv...

Serial blood draws for the assessment of trauma patients' hemoglobin (sHgb) and hematocrit (sHct) is standard practice. A device that would allow for continuous real-time, non-invasive monitoring of hemoglobin and tissue perfusion would potentially improve recognition, monitoring and resuscitation of blood loss. We developed a device utilizing diffuse optical spectroscopy (DOS) technology that ...

Denial of Service (DoS) has become a prevalent threat in today’s networks. Motivated by an impressive variety of reasons and directed against an equally impressive variety of targets, DoS attacks are not as difficult to launch as one would expect. Protection against them is, however, disproportionately difficult. Despite the extensive research in recent years, DoS attacks continue to harm. In o...

The specification of the R7 photoreceptor cell in the developing eye of Drosophila is dependent upon activation of the Sevenless (SEV) receptor tyrosine kinase. By screening for mutations that suppress signaling via a constitutively activated SEV protein, we have identified a novel gene, daughter of sevenless (dos). DOS is required not only for signal transduction via SEV but also in other rece...

Diversity-oriented synthesis (DOS) can provide a collection of diverse and complex drug-like small molecules, which is critical in the development of new chemical probes for biological research of undruggable targets. However, the design and synthesis of small-molecule libraries with improved biological relevance as well as maximized molecular diversity represent a key challenge. Herein, we emp...