Gastric Outlet Obstruction at Bugando Medical Centre in Northwestern Tanzania: A Prospective Review of 184 Cases.

Gastric outlet obstruction poses diagnostic and therapeutic challenges to general surgeons practicing in resource-limited countries. There is a paucity of published data on this subject in our setting. This study was undertaken to highlight the etiological spectrum and treatment outcome of gastric outlet obstruction in our setting and to identify prognostic factors for morbidity and mortality. This was a descriptive prospective study which was conducted at Bugando Medical Centre between March 2009 and February 2013. All patients with a clinical diagnosis of gastric outlet obstruction were, after informed consent for the study, consecutively enrolled into the study. Statistical data analysis was done using SPSS computer software version 17.0. A total of 184 patients were studied. More than two-third of patients were males. Patients with malignant gastric outlet obstruction were older than those of benign type. This difference was statistically significant (p < 0.001). Gastric cancer was the commonest malignant cause of gastric outlet obstruction where as peptic ulcer disease was the commonest benign cause. In children, the commonest cause of gastric outlet obstruction was congenital pyloric stenosis (13.0%). Non-bilious vomiting (100%) and weight loss (93.5%) were the most frequent symptoms. Eighteen (9.8%) patients were HIV positive with the median CD 4+ count of 282 cells/μl. A total of 168 (91.3%) patients underwent surgery. Of these, gastro-jejunostomy (61.9%) was the most common surgical procedure performed. The complication rate was 32.1 % mainly surgical site infections (38.2%). The median hospital stay and mortality rate were 14 days and 18.5% respectively. The presence of postoperative complication was the main predictor of hospital stay (p = 0.002), whereas the age > 60 years, co-existing medical illness, malignant cause, HIV positivity, low CD 4 count (<200 cells/μl), high ASA class and presence of surgical site infection significantly predicted mortality ( p< 0.001). The follow up of patients was generally poor as more than 60% of patients were lost to follow up. Gastric outlet obstruction in our setting is more prevalent in males and the cause is mostly malignant. The majority of patients present late with poor general condition. Early recognition of the diagnosis, aggressive resuscitation and early institution of surgical management is of paramount importance if morbidity and mortality associated with gastric outlet obstruction are to be avoided

Bacteriophage T4 gp2 Interferes with Cell Viability and with Bacteriophage Lambda Red Recombination

ABSTRACT The T4 head protein, gp2, promotes head-tail joining during phage morphogenesis and is also incorporated into the phage head. It protects the injected DNA from degradation by exonuclease V during the subsequent infection. In this study, we show that recombinant gp2, a very basic protein, rapidly kills the cells in which it is expressed. To further illustrate the protectiveness of gp2 for DNA termini, we compare the effect of gp2 expression on Red-mediated and Int-mediated recombination. Red-mediated recombination is nonspecific and requires the transient formation of double-stranded DNA termini. Int-mediated recombination, on the other hand, is site specific and does not require chromosomal termini. Red-mediated recombination is inhibited to a much greater extent than is Int-mediated recombination. We conclude from the results of these physiological and genetic experiments that T4 gp2 expression, like Mu Gam expression, kills bacteria by binding to double-stranded DNA termini, the most likely mode for its protection of entering phage DNA from exonuclease V.</jats:p

A Novel Clustering Protocol for Network Lifetime Maximization in Underwater Wireless Sensor Networks

Underwater wireless sensor network (UWSN) is a pervasive technology with different characteristics and requirements, where energy conservation is a stringent requirement. Improving the network lifetime can have tremendous practical utility in these networks. The energy of the nodes in the network can be conserved by devising an efficient cluster head selection mechanism. This paper presents a novel energy-efficient clustering protocol (EECP) for the UWSN. The proposed protocol segregates the network based on horizontal clustering. In every iteration, the cluster heads are selected based on the energy level of the nodes. The performance of the proposed protocol is measured in terms of energy efficiency and network lifetime. Moreover, the performance of the EECP is further improved by adding nearest neighbor criteria for selecting the cluster head. This protocol is named as energy-efficient clustering protocol with nearest neighbor (EECP-NN). The efficacy of the proposed protocols is evaluated by comparing their performance with some of the state-of-the-art cluster-based protocols in this study.https://ieeexplore.ieee.org/abstract/document/1046353

A Blockchain-Enabled Approach for Enhancing Synchrophasor Measurement in Smart Grid 3.0

Smart Grid 3.0 is the latest evolution of the smart grid and incorporates advanced computing and communication technologies. The synchrophasor communication system plays a critical role in wide-area measurement systems (WAMS) for real-time protection and control of power systems, supporting the objectives of Smart Grid 3.0. This system relies on synchrophasor communication technologies, where Phasor Measurement Units (PMUs) transmit synchrophasor data to Phasor Data Concentrators (PDCs) over the synchrophasor communication network. The communication infrastructure of this network is based on the TCP/IP protocol stack, which, unfortunately, is susceptible to cyberattacks, posing security threats such as data tampering and false data injection. These vulnerabilities undermine the intended benefits of synchrophasor applications in terms of situational awareness, observability, grid reliability, resiliency, and synchronized monitoring and control in the smart grid. To address these challenges, it is crucial to enhance the security, integrity, and confidentiality of synchrophasor data within the communication system. This paper proposes a blockchain-based synchrophasor communication system that preserves the security and integrity of synchrophasor data. In this paper, an architecture is proposed for a synchrophasor communication system based on blockchain technology. The proposed architecture aims to enhance the security and integrity of synchrophasor measurements. Furthermore, the architecture is developed as a peer-to-peer distributed blockchain network, leveraging the robustness of a distributed, decentralized, hierarchical PDC architecture. To evaluate the efficacy of the proposed architecture, two case studies, one using the IEEE 9 bus and the other using IEEE 14 bus systems are considered. Moreover, various challenges with potential solutions are also recommended. The proposed work is envisioned to contribute to the advancement of Smart Grid 3.0 by adopting blockchain technology for synchrophasor applications

Challenges and Solutions for Vehicular Ad-Hoc Networks Based on Lightweight Blockchains

Current research with Vehicular Ad-hoc Networks (VANETs) has focused on adapting an efficient consensus mechanism and reducing the blockchain size while maintaining security. Care must be taken when implementing blockchains within VANET applications to leverage the chains’ strengths while mitigating their weaknesses. These chains can serve as distributed ledgers that provide storage for more than financial transactions. The security provided by longer blockchains constitutes a nearly immutable, decentralized data structure that can store any data relevant to the applications. However, these chains must be adapted to the ad-hoc, resource-constrained environments found in VANETs. In the absence of abundant resources and reliable network connections, chain operation and maintenance must address the challenges presented by highly mobile nodes in novel ways, including situations such as emergency messaging that require real-time responses. Researchers have included different mechanisms to realize lightweight blockchains, such as adding reputation to existing consensus mechanisms, condensing the consensus committees, using geographical information, and monitoring a nodes behavior in attempts to adapt blockchains to these domains. This paper analyzes the challenges and gives solutions for these different mechanisms to realize lightweight blockchains for VANETs