Geographical Forwarding Methods in Vehicular Ad hoc Networks

Vehicular ad hoc networks are new and emerging technology and special class of mobile ad hoc networks that provide wireless communication between vehicles without any fixed infrastructure. Geographical routing has appeared as one of the most scalable and competent routing schemes for vehicular networks. A number of strategies have been proposed for forwarding the packets in geographical direction of the destination, where information of direct neighbors is gained through navigational services. Due to dynamically changing topologies and high mobility neighbor information become outdated. To address these common issues in network different types of forwarding strategies have been proposed. In this review paper, we concentrate on beaconless forwarding methods and their forwarding methods in detail

Methane and n-hexane ignition in a newly developed diaphragmless shock tube

Shock tubes have been routinely used to generate reliable chemical kinetic data for gas-phase chemistry. The conventional diaphragm-rupture mode for shock tube operation presents many challenges that may ultimately affect the quality of chemical kinetics data. Numerous diaphragmless concepts have been developed to overcome the drawbacks of using diaphragms. Most of these diaphragmless designs require significant alterations in the driver section of the shock tube and, in some cases, fail to match the performance of the diaphragm-mode of operation. In the present work, an existing diaphragm-type shock tube is retrofitted with a fast-acting valve, and the performance of the diaphragmless shock tube is evaluated for investigating the ignition of methane and n-hexane. The diaphragmless shock tube reported here presents many advantages, such as eliminating the use of diaphragms, avoiding substantial manual effort during experiments, automating the shock tube facility, having good control over driver conditions, and obtaining good repeatability for reliable gas-phase chemical kinetic studies. Ignition delay time measurements have been performed in the diaphragmless shock tube for three methane mixtures and two n-hexane mixtures at $P_5$ = 10 - 20 bar and $T_5$ = 738 - 1537 K. The results obtained for fuel-rich, fuel-lean, and oxygen-rich (undiluted) mixtures show very good agreement with previously reported experimental data and literature kinetic models (AramcoMech 3.0 [1] for methane and Zhang et al. mechanism [2] for n-hexane). The study presents an easy and simple method to upgrade conventional shock tubes to a diaphragmless mode of operation and opens new possibilities for reliable chemical kinetics investigations.Comment: 22 pages, 9 figure

Association between circulating adiponectin levels and polycystic ovarian syndrome

Background: Low adiponectin levels in polycystic ovarian syndrome (PCOS) have been largely attributed to obesity which is common among these patients. In addition, evidence also suggests that low adiponectin in PCOS may be related to insulin resistance (IR) in these women. However, studies on the role of adiponectin in younger and lean patients are limited. Therefore, the aim of the present study was to examine the association of adiponectin levels in young and lean women with PCOS.<p></p> Methods: A case–control study was conducted at the Dow University of Health Sciences, Karachi, Pakistan. Cases were 75 patients of PCOS with Body Mass Index (BMI) &23 aged 16–35 years and 75 healthy age and BMI matched controls were selected from family and friends of the cases. Demographic details, family history and past medical history were obtained through interview by a physician. Anthropometric measurements included weight and height of the participants. Fasting glucose, total cholesterol, high-density lipoprotein (HDL), insulin, adiponectin, and androgen levels were determined. IR was calculated using homeostasis model assessment for insulin resistance (HOMA-IR). Logistic regression models were used to assess the association between adiponectin and PCOS after adjusting for co-variates.<p></p> Results: On multivariable analysis, PCOS cases were 3.2 times more likely to have low adiponectin level (OR = 3.2, 95% CI 1.49-6.90, p-value 0.003) compared to the controls after adjustment for age, BMI, family history, marital status, total cholesterol, HDL level and IR. Females with a family history of PCOS were significantly more likely to have lower adiponectin (OR = 3.32, 95% CI 1.27-8.67, p-value 0.014) compared to those who did not have a family history of PCOS. The associations of IR and family history with low adiponectin level also remained statistically significant after adjustments for covariates.<p></p> Conclusion: Serum adiponectin levels are independently associated with PCOS and are only partly explained by IR. Adiponectin level may serve as a potential independent biomarker for diagnosis of PCOS in young and lean women with fewer symptoms, or women with a family history of PCOS

Osjetljiva kinetička spektrofotometrijska metoda za određivanje kaptoprila

A simple and sensitive kinetic spectrophotometric method has been developed. The method is based on the reduction of Fe(III) with captopril. Fe(II) then reacts with potassium ferricyanide, resulting in the formation of a blue product. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 730 nm. Thus, 1.23 × 10-3 mol L-1 FeCl3 and 3.04 × 10-4 mol L-1 potassium ferricyanide were used as optimum values for maximum concentration of captopril in the calibration graph. The initial rate is utilized for constructing the calibration graph, which was found to be linear in the range 4.60 × 10–6–5.06 × 10–5 mol L-1; detection limit is 1.99 × 10–7 mol L-1. The proposed method has been validated; the mean recovery ranges from 99.8–101.4% with RSD < 2%. Common excipients do not interfere with the determination. The point and interval hypotheses tests have been performed and confirmed that there is no significant difference between the proposed method and conventional spectrophotometric method. The experimental true bias of all samples is lower than ± 2.0%. The proposed method has been applied to the determination of captopril in bulk and dosage forms.Razvijena je jednostavna osjetljiva kinetička spektrofotometrijska metoda za određivanje kaptoprila. Metoda se temelji na redukciji Fe(III) u Fe(II) koji zatim s kalijevim fericijanidom daje plavo obojeni produkt. Nastajanje produkta praćeno je spektrofotometrijski na valnoj duljini 730 nm. Optimalne koncentracije FeCl3 i potassium ferricyanida bile su 1,23 × 10-3 mol L-1, odnosno 3,04 × 10-4 mol L-1. Početna brzina upotrebljena je za izradu baždarnog pravca. Linearnost je postignuta u koncentracijskom području od 4,60 × 10–6 do 5,06 × 10–5 mol L-1; granica detekcije bila je 1,99 × 10–7 mol L-1. Predložena metoda je validirana. Srednja vrijednost analitičkog povrata iznosila je 99,8–101,4% uz RSD < 2%. Uobičajeni ekscipiensi nisu smetali određivanju. Ispitivanja hipoteze točke i intervala potvrdila su da nema značajne razlike između predložene metode i opisane spektrofotometrijske metode. Stvarna eksperimentalna pogreška za sve uzorke bila je manja od ± 2%. Opisana metoda primijenjena je za određivanje kaptoprila kao čiste supstancije i u ljekovitom pripravku

Dual-camera high-speed imaging of n-hexane oxidation in a high-pressure shock tube

Shock tubes are widely used in the study of chemical kinetics. Its benefits rely on the almost ideal shock-heating process that provides high temperatures and pressures to a chemical system for a limited test time. Just like any reactor, shock tubes are not immune to non-ideal effects. The study of conditions that might deviate experiments from ideal conditions is thus of the utmost importance. High-speed imaging has been proven to be a powerful bytool to analyze non-ideal / non-homogenous combustion in shock tubes. In this work, dual-camera high-speed imaging experiments were performed at 10, 15 and 20 bar in a high-pressure shock tube (HPST). An optical section was designed as an extension of the HPST which enabled simultaneous visualization from the endwall and the sidewall of the driven section of the shock tube. n-Hexane, a fuel with a negative temperature coefficient (NTC) behavior that has been identified as prone to non-homogenous ignition, is used as a test fuel. Reactive mixtures and thermodynamic conditions were selected to visually analyze ignition processes at the high-temperature, NTC and low-temperature regimes. Non-homogeneous ignition was observed mostly at the local maximum of the IDT, which is comprised by the high-temperature and NTC regions. Stoichiometric n-hexane mixture with high fuel loading (5% n-hexane) presented the highest deviation from constant volume chemical kinetic simulations. The inclusion of helium as a bath gas to mitigate preignition was tested and it showed to improve the susceptibility of the mixtures to develop reaction fronts. The modified Sankaran criterion for the identification of ignition regimes in shock tubes was tested and it showed an overall good agreement against the experimental observations.Comment: 23 pages, 11 figures, 1 tabl

Size of the Government, Quality of Institutions and Growth in SAARC Countries

One elusive question still attracts the attention of the researchers and policy makers whether government has a positive or negative role in the growth of a country. Washington consensus depressed the role of the government as an anchor of growth, while the post Washington consensus again focuses on the role of the government as the major player to revive growth. Theoretically, the linkages have been well established between the government spending and growth. However, the extensive use of cross country growth regressions in 1980s and 1990s highlighted the controversies in the empirical testing of these schools of thought using data for different countries and different techniques to prove their hypothesis. Most of these studies concentrated on the developed countries, while few try to explore the structure in developing countries. The question still remains, whether public sector promotes or retards growth

Wireless sensor network performance analysis and effect of blackhole and sinkhole attacks

The widespread usage of Wireless sensor networks in various fields and application make it vulnerable to variety of security threats and attacks. These security attacks occur when an adversary compromised a sensor node by inject false measurements and divert real time network traffic. Sinkhole and Blackhole attacks are very common attacks in network, where an attacker advertises un-authorized routing update in network. To deal with these types of attacks, there is a need to tighten the network security and prevent from attackers. In this study, we discuss security threats and presents the effects of Black and Sink hole attacks. Further, the study presents related work and current issues in wireless sensor network. The simulation results illustrated that, how these attacks affect the network performance