Protocols and sockets [Internet programming]

With the world rapidly changing into a global village, the necessity of interconnecting computers is exponentially increasing. The greatest hand in conjoining computers is the Internet. With rapid advancement development (RAD) tools, Internet programming has become a piece of cake for the developers. Now a novice programmer can develop applications encompassing common web protocols just by dragging and dropping. The API era has been washed out     

Respiratory effects in people exposed to arsenic via the drinking water and tobacco smoking in southern part of Pakistan

In this study, a survey has been conducted during 2005-2007 on surface and groundwater arsenic (As) contamination and its impact on the health of local population, of villages located on the banks of Manchar lake, southern part of Sindh, Pakistan. We have also assessed the relationship between arsenic exposure through respiratory disorders in male subjects with drinking water and smoking cigarettes made from tobacco grown in agricultural land irrigated with As contaminated lake water. The biological samples (blood and scalp hair) were collected from As exposed subjects (100% smokers) and age matched healthy male subjects (40.2% smoker and 59.8% non smokers) belong to unexposed areas for comparison purposes. The As concentration in drinking water (surface and underground water), agricultural soil, cigarette tobacco and biological samples were determined by electrothermal atomic absorption spectrometry. The range of As concentrations in lake water was 35.2-158 µg/L (average 97.5 µg/L), which is 3-15 folds higher than permissible limit of World Health Organization (WHO, 2004). While the As level in local cigarette tobacco was found to be 3-6 folds higher than branded cigarettes (0.37-0.79 µg/g). Arsenic exposed subjects (with and without RD) had significantly elevated levels of As in their biological samples as compared to referent male subject of unexposed area. These respiratory effects were more pronounced in individuals who had also As induced skin lesions. The linear regressions showed good correlations between As concentrations in water versus hair and blood samples of exposed subjects with and without respiratory problems.     

NATURAL CONVECTION IN A TWO-DIMENSIONAL DIFFERENTIALLY HEATED SQUARE ENCLOSURE UNDERGOING ROTATION

A numerical study of two-dimensional natural convection in a rotating and differentially heated square enclosure has been presented by solving the conservation equations of mass, momentum, and energy in a rotating coordinate system using the finite difference method. Considering air to be the fluid medium in the cavity, the results are presented for a wide range of Rayleigh numbers (Ra), Taylor numbers (Ta), and rotational Rayleigh numbers (Ra _w). It is found that a significant enhancement in heat transfer can be achieved due to rotational effects. At a particular Ra, increase in Ta results in an increase in frequency of oscillations of the dynamical variables and also gives rise to formation of a mushroom-shaped plume in the core of the cavity. For constant Ta, an increase in Ra results in formation of thinner thermal boundary layers at the isothermal walls and stable thermal stratification in the core of the cavity. The stratification becomes unstable when the Ta     

EVOLUTION TO CHAOTIC NATURAL CONVECTION IN A RECTANGULAR ENCLOSURE WITH MIXED BOUNDARY CONDITIONS

The purpose of this numerical study is to analyze the characteristics of transition from laminar to chaotic natural convection in a fluid-filled two-dimensional, unity aspect ratio rectangular cavity with mixed thermal boundary conditions. For a medium Prandtl number fluid ( Pr ) the numerical solution of the two-dimensional Navier-Stokes momentum and energy equation with Bousinessq approximation, it is found that there are finite Rayleigh numbers Ral Ra2, and Ra3 for the onset of single-, double-, and multiple-frequency oscillatory motion at different spatial locations in the enclosure. As Ra increases, the flow exhibits a change from steady convection to periodic to quasi-periodic flow, while no period doubting is observed. The onset of strong chaos appears when Ra = 57,000 Rac. This system does not revert to steady state convection for Rac as high as 285,000. As Ra increases, various measures of chaos, such as power spectrum, Poincare sections, phase portrait, and time series of various dynamical variable signals, all show an increasing degree of characteristics of chaos,     

A Set of Neural Tools for Human-Computer Interactions: Application to the Handwritten Character Recognition, and Visual Speech Recognition Problems

This paper presents a new technique of data coding and an associated set of homogenous processing tools for the development of Human Computer Interactions (HCI). The proposed technique facilitates the fusion of different sensorial modalities and simplifies the implementations. The coding takes into account the spatio-temporal nature of the signals to be processed in the framework of a sparse representation of data. Neural networks adapted to such a representation of data are proposed to perform the recognition tasks. Their development is illustrated by two examples: one of on-line handwritten character recognition; and the other of visual speech recognition.     

On the peak-to-average power ratio reduction in mobile WiMAX: A discrete cosine transform matrix precoding based random-interleaved orthogonal frequency division multiple access uplink system

Mobile worldwide interoperability for microwave access (Mobile WiMAX) is a broadband wireless solution that enables the convergence of mobile and fixed broadband networks through a common wide area radio-access (RA) technology and flexible network architecture. Since January 2007, the IEEE 802.16 working group (WG) has been developing a new amendment of the IEEE 802.16 standard i.e. IEEE 802.16 m as an advanced air interface to meet the requirements of ITU-R/IMT-Advanced for 4 G systems. The mobile WiMAX air interface adopts orthogonal frequency division multiple access (OFDMA) as multiple access technique for its uplink (UL) and downlink (DL) to improve the multipath performance. All OFDMA based networks, including mobile WiMAX experiences the problem of high peak-to-average power ratio (PAPR). This paper presents: Discrete-Cosine transform matrix (DCTM) precoding based random-interleaved OFDMA uplink system and selecting mapping (SLM) based DCTM precoded random-interleaved OFDMA uplink system respectively, for PAPR reduction in mobile WiMAX systems. PAPR of the proposed systems is analyzed with the root-raised-cosine (RRC) pulse shaping to keep out of band radiation low and to meet the transmission spectrum mask requirement. Simulation results show that, the proposed systems have low PAPR than the Walsh-Hadamard transform (WHT) precoded random-interleaved OFDMA uplink systems and the conventional random-interleaved OFDMA uplink systems. Symbol-error-rate (SER) performance of the proposed system is also better than the conventional random-interleaved OFDMA uplink systems and at par with WHT based random-interleaved OFDMA uplink systems. Good improvement in PAPR and SER offered by the proposed systems can notably reduce the cost and complexity of the transmitter.     

Synthesis and characterization of polyaniline–titanium(IV)phosphate cation exchange composite: Methanol sensor and isothermal stability in terms of DC electrical conductivity

Electrically conductive composite of polyaniline–titanium(IV)phosphate (PANI–TiP) was synthesized by sol–gel method. The obtained composite was characterized by using Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The composite showed good ion-exchange capacity and isothermal stability in terms of DC electrical conductivity retention at an ambient conditions below 100 °C. The composite material was investigated as alcohol vapors sensor and compared with blank polyaniline. The results showed that the composite was more selective and sensitive towards methanol vapors.     

Craniocervical junction tuberculosis: a rare but dangerous disease

BACKGROUND: Mycobacterium tuberculosis of the cervical spine is a rare but dangerous manifestation of extra-pulmonary tuberculosis. The clinical picture ranges from early, nonspecific, insidious symptoms to severe neurological complications and death, attributed to craniocervical junction instability and cervicomedullary compression. The different lines of management include antituberculous medication with traction and external fixation or adjunctive surgery (debridement and stabilization) in patients with severe or persistent neurological complications and/or vertebral instability. METHODS: We describe two patients with advanced craniocervical junction tuberculosis. The early clinical picture was nonspecific in Case 1 and obscured by psychiatric illness in Case 2. The detailed clinical and radiological findings, and the management, will be described. Involvement of the occipital condyles and foramen magnum, which has not been reported previously, will be demonstrated. RESULTS: Both cases underwent transoral biopsy, aspiration, and debridement of retropharyngeal abscess (granuloma). Histological and tissue culture studies proved the abscesses were tuberculous and anti-tuberculous medications were started. Case 1 showed complete resolution of the clinical and radiological findings. Case 2 developed cardiorespiratory arrest while in a halo jacket. He was resuscitated but remained quadriplegic and semiconscious; he developed nosocomial gram negative pneumonia. He was referred back to his local hospital where he died 1 year later. CONCLUSIONS: Tuberculosis is an infrequent but notable cause of cervicomedullary compression. It should be suspected in patients with infective spondylitis who are immunocompromised or reside in an area highly endemic for tuberculosis. Management strategies include antituberculosis medication, transoral biopsy and drainage of the abscess, traction and external fixation, posterior decompression, and internal fixation, according to the clinical and radiological findings.