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A new dispersion-relation preserving method for integrating the classical Boussinesq equation
No full textAbstractIn this paper, a dispersion-relation preserving method is proposed for nonlinear dispersive waves, starting from the oldest weakly nonlinear dispersive wave mathematical model in shallow water waves, i.e., the classical Boussinesq equation. It is a semi-analytic procedure, however, which preserves, as a distinctive feature, the dispersion-relation imbedded in the model equation without adding (unwelcome) numerical effects, i.e., the proposed method has the same dispersion-relation as the original classical Boussinesq equation. This remarkable (dispersion-relation) preserving property is proved mathematically for small wave motion in present study. The property is also numerically examined by observing both the local wave number and the local frequency of a slowly varying water-wave group. The dispersion-relation preserving method proposed here is powerful as well for observing nonlinear wave phenomena such as solitary waves and their collision. In fact, the main features of nonlinear wave characteristics are clearly seen through not only a single propagating solitary wave but counter-propagating (head-on) solitary wave collisions. They are compared with known (exact) nonlinear solutions, the results of which represent a major improvement over existing solution formulations in the literature
Ice core and climate reanalysis analogs to predict Antarctic and Southern Hemisphere climate changes
No full textAbstractA primary goal of the SCAR (Scientific Committee for Antarctic Research) initiated AntClim21 (Antarctic Climate in the 21st Century) Scientific Research Programme is to develop analogs for understanding past, present and future climates for the Antarctic and Southern Hemisphere. In this contribution to AntClim21 we provide a framework for achieving this goal that includes: a description of basic climate parameters; comparison of existing climate reanalyses; and ice core sodium records as proxies for the frequencies of marine air mass intrusion spanning the past ∼2000 years. The resulting analog examples include: natural variability, a continuation of the current trend in Antarctic and Southern Ocean climate characterized by some regions of warming and some cooling at the surface of the Southern Ocean, Antarctic ozone healing, a generally warming climate and separate increases in the meridional and zonal winds. We emphasize changes in atmospheric circulation because the atmosphere rapidly transports heat, moisture, momentum, and pollutants, throughout the middle to high latitudes. In addition, atmospheric circulation interacts with temporal variations (synoptic to monthly scales, inter-annual, decadal, etc.) of sea ice extent and concentration. We also investigate associations between Antarctic atmospheric circulation features, notably the Amundsen Sea Low (ASL), and primary climate teleconnections including the SAM (Southern Annular Mode), ENSO (El Nîno Southern Oscillation), the Pacific Decadal Oscillation (PDO), the AMO (Atlantic Multidecadal Oscillation), and solar irradiance variations
Preparation of nanostructured ruthenium doped titania for the photocatalytic degradation of 2-chlorophenol under visible light
No full textAbstractRu doped titania was prepared by the impregnation method and examined for the photocatalytic degradation of 2-chlorophenol at ambient conditions. Ru/TiO2 photocatalysts with metal loadings of 0.2, 0.4, 0.6 and 0.8wt% were prepared and characterized using TEM, XRD, FTIR, SBET and EDX analyses. The degradation of 2-chlorophenol (2-CP) in the aqueous phase was investigated under irradiation at 254nm, employing either photodegradation in the presence of titania, Ru doped titania or photolysis, to compare the efficiency of these photoinduced advanced oxidation techniques. Photocatalysis under visible irradiation was also investigated. The removal efficiency arrived at 50% using 0.2% Ru/TiO2 catalyst
Widespread, routine occurrence of pharmaceuticals in sewage effluent, combined sewer overflows and receiving waters
No full textAbstractResearch addressing the occurrence, fate and effects of pharmaceuticals in the aquatic environment has expanded rapidly over the past two decades, primarily due to the development of improved chemical analysis methods. Significant research gaps still remain, however, including a lack of longer term, repeated monitoring of rivers, determination of temporal and spatial changes in pharmaceutical concentrations, and inputs from sources other than wastewater treatment plants (WWTPs), such as combined sewer overflows (CSOs). In addressing these gaps it was found that the five pharmaceuticals studied were routinely (51–94% of the time) present in effluents and receiving waters at concentrations ranging from single ng to μg L−1. Mean concentrations were in the tens to hundreds ng L−1 range and CSOs appear to be a significant source of pharmaceuticals to water courses in addition to WWTPs. Receiving water concentrations varied throughout the day although there were no pronounced peaks at particular times. Similarly, concentrations varied throughout the year although no consistent patterns were observed. No dissipation of the study compounds was found over a 5 km length of river despite no other known inputs to the river. In conclusion, pharmaceuticals are routinely present in semi-rural and urban rivers and require management alongside more traditional pollutants
Novel feature extraction technique for the recognition of handwritten digits
No full textAbstractThis paper presents an efficient handwritten digit recognition system based on support vector machines (SVM). A novel feature set based on transition information in the vertical and horizontal directions of a digit image combined with the famous Freeman chain code is proposed. The main advantage of this feature extraction algorithm is that it does not require any normalization of digits. These features are very simple to implement compared to other methods. We evaluated our scheme on 80,000 handwritten samples of Persian numerals and we have achieved very promising results
Hepatitis C virus and cardiovascular: A review
No full textAbstractChronic hepatitis C virus (HCV) infection is a systemic disease that leads to increased risks of cirrhosis and its complications, as well as extrahepatic disturbances, including immune-related disorders and metabolic alterations such as insulin resistance and steatosis. Recent accumulating evidence suggests that HCV infection can increase cardiovascular risk, and that viral eradication can improve cardiovascular outcomes in the clinical setting. These data are strengthened by evidence identifying potential mechanisms (in)directly linking HCV infection to vascular damage. However, the high prevalence of both HCV infection and cardiovascular alterations, as well as the presence of contrasting results not identifying any association between HCV infection and cardiovascular dysfunction, provides uncertainty about a direct association of HCV infection with cardiovascular risk. Further studies are needed to clarify definitively the role of HCV infection in cardiovascular alterations, as well as the impact of viral eradication on cardiovascular outcomes. These features are now more attractive, considering the availability of new, safe, and very effective interferon-free antiviral agents for the treatment of HCV infection. This review aims to discuss carefully available data on the relationship between HCV infection and cardiovascular risk
Lack of the P2X7 receptor protects against AMD-like defects and microparticle accumulation in a chronic oxidative stress-induced mouse model of AMD
No full textAbstractThe P2X7 receptor (P2X7R) is an ATP-gated ion channel that is a key player in oxidative stress under pathological conditions. The P2X7R is expressed in the retinal pigmented epithelium (RPE) and neural retina. Chronic oxidative stress contributes to the pathogenesis of age-related macular degeneration (AMD). Mice lacking Cu, Zn superoxide dismutase (Sod1) developed chronic oxidative stress as well as AMD-like features, but whether the P2X7R plays a causative role in oxidative stress-induced AMD is unknown. Thus, the main purpose of this study was to test if concurrent knockout (KO) of P2X7R could block AMD-like defects seen in Sod1 KO mice. Using multiple approaches, we demonstrate that Sod1 KO causes AMD-like defects, including positive staining for oxidative stress markers, 3-nitrotyrosine and carboxymethyl lysine, thinning of the RPE and retina, thickening of Bruch's membrane, presence of basal laminar and linear deposits, RPE barrier disruption and accumulation of microglia/macrophages. Moreover, we find that Sod1 KO mice accumulate more microparticles (MPs) within RPE/choroid tissues. Concurrent KO of the P2X7R protects against AMD-like defects and MP accumulation in Sod1 KO mice. Together, we show for the first time, that deficiency of P2X7R prevents in vivo oxidative stress-induced accumulation of MPs and AMD-like defects. This work could potentially lead to novel therapies for AMD and other oxidative stress-driven diseases
The strain – Counter strain technique in the management of anterior interosseous nerve syndrome: A case report
No full textAbstractAnterior interosseous nerve syndrome (AINS) is a proximal median nerve neuropathy affecting the forearm. Trigger points in the anterior compartment of the forearm may cause compression of the anterior interosseous nerve (AIN) which, in turn, may result in muscle weakness. Here we present the case of a 37-year-old female who complained of an abnormal pen grip while writing. Clinical examination (observation, palpation, pincer grip strength) showed weak pincer grip strength, an active trigger point in the middle of the anterior forearm and a positive circle sign. Her treatment course included cryomassage, neural mobilization, transcutaneous electrical nerve stimulation (TENS) and the strain-counter strain (SCS) technique four times a week for two weeks. On follow-up, the patient reported an inactive trigger point on palpation, improvement in her handwriting and improved pincer (fingertip pinch) grip strength in pounds (lbs) as recorded by the Baseline Hydraulic Pinch Gauge. This case report explored the effectiveness of SCS as an important adjunct to other conservative treatments for entrapment neuropathies. SCS has also shown its potential to improve muscle strength
Persistence of metalaxyl residues on tomato fruit using high performance liquid chromatography and QuEChERS methodology
No full textAbstractMetalaxyl is a widely used fungicide around the world. Very limited data have been reported concerning the dissipation and residue of metalaxyl in agricultural products. Residues and dissipation rate of metalaxyl were estimated in tomato fruit by HPLC following single application of the fungicide at 262.5g a.i. ha−1. The average initial deposit of metalaxyl on tomato fruits was found to be 2.39mgkg−1. Residues of metalaxyl dissipated below the maximum residue limit (MRL) of 0.5mgkg−1 in 7days. Half-life (t1/2) for degradation of metalaxyl on tomato fruit was observed to be 1.81days. A waiting period of 7days is suggested for safe consumption of tomato. The results would be useful for the safe use of metalaxyl and to prevent any health problem to customers
Cave stratigraphies and cave breccias: Implications for sediment accumulation and removal models and interpreting the record of human occupation
No full textAbstractMany of the key debates in archaeology hinge on the chronology and interpretation of data gathered from cave and rockshelter stratigraphies, especially those in karstic limestone environments which are selectively targeted by archaeologists because of their superior preservation characteristics. It has long been recognized that such sites often contain a variety of cemented deposits including cave breccias and that some breccias contain anthropogenic inclusions such as stone artefacts, shell and burnt animal bones. Cementation enhances the survival through time of such brecciated deposits. This can result in chrono-stratigraphic intervals surviving on cave walls and speleothems that are no longer represented in the stratigraphy of cave floors. This has important implications for understanding apparent presence/absence of human occupation and cultural continuity as seen in archaeo-stratigraphy in caves and rockshelters, especially in relation to human migration in the humid tropics in SE Asia and the Pacific, and over Pleistocene to Holocene timescales. Here we discuss localized breccia formation, the erosional processes that leave remnant deposits adhering to walls and speleothems at heights well above current cave floors, and the possible significance of local and regional processes, especially changing base levels, in triggering gutting out phases impacting cave floor sediment architectures. Equally significant in terms of chronological completeness, representativeness and bias is the contribution made by cultural materials encased in older breccias as they erode and are (re-)incorporated into younger accumulating cultural deposits. Case studies from cave sites in Papua New Guinea and Timor Leste are used to illustrate these issues