1,499 research outputs found
Influence of finite volume and magnetic field effects on the QCD phase diagram
The Polyakov linear sigma model (PLSM) is used to investigate the respective
influence of a finite volume and a magnetic field on the quark-hadron phase
boundary in the plane of baryon chemical potential () vs. temperature
() of the QCD phase diagram. The calculated results indicate sizable shifts
of the quark-hadron phase boundary to lower values of
for increasing magnetic field strength, and an opposite shift to higher values
of for decreasing system volume. Such shifts could
have important implications for extraction of the thermodynamic properties of
the QCD phase diagram from heavy ion data
Distance from a fishing community explains fish abundance in a no-take zone with weak compliance
There are numerous examples of no-take marine reserves effectively conserving fish stocks within their boundaries. However, no-take reserves can be rendered ineffective and turned into ‘paper parks’ through poor compliance and weak enforcement of reserve regulations. Long-term monitoring is thus essential to assess the effectiveness of marine reserves in meeting conservation and management objectives. This study documents the present state of the 15-year old no-take zone (NTZ) of South El Ghargana within the Nabq Managed Resource Protected Area, South Sinai, Egyptian Red Sea. Previous studies credited willing compliance by the local fishing community for the increased abundances of targeted fish within the designated NTZ boundaries compared to adjacent fished or take-zones. We compared benthic habitat and fish abundance within the NTZ and the adjacent take sites open to fishing, but found no significant effect of the reserve. Instead, the strongest evidence was for a simple negative relationship between fishing pressure and distance from the closest fishing village. The abundance of targeted piscivorous fish increased significantly with increasing distance from the village, while herbivorous fish showed the opposite trend. This gradient was supported by a corresponding negative correlation between the amount of discarded fishing gear observed on the reef and increasing distance from the village. Discarded fishing gear within the NTZ suggested decreased compliance with the no-take regulations. Our findings indicate that due to non-compliance the no-take reserve is no longer functioning effectively, despite its apparent initial successes and instead a gradient of fishing pressure exists with distance from the nearest fishing community
Non-linear optimization for parameter estimation for flood forecasting
Floods are the response of a catchment area to
severe rainfall events. Each catchment will have
its unique response which is dependent on its own
characteristics and the temporal and spatial
distribution of the oncoming rainfall event. A non
linear optimization technique has been applied to
historical data for rainfall and river flows of the
Kakanui catchment in North Otago, New Zealand,
to estimate the parameters of a model based on
the transfer function concept. The non linear
optimization is based on Powell algorithm.
Powell algorithm has been widely used in the
literature, and it is more efficient and faster than
the Simplex method (Press et al., 1989)
Observed rainfall events at two locations in the
Kakanui catchment, along with the corresponding
observed flows of the river have been utilized to
estimate the transfer function which represents the
response of the Kakanui catchment to rainfall
events. An adjusted form of Philip’s equation for
infiltration was used to estimate the abstraction of
the rainfall event and obtain the effective rainfall
which will contribute to the river flow. Weighing
factors were assigned to each of the rainfall sites
to obtain the best fit between observed and
forecasted flows. Nine flood events were used for
the calibration process, while two events were
utilized for the validation of the derived model.
The model has 19 parameters for the transfer
function, 2 parameters for the hydrologic
abstractions model, and 2 parameters for the
weighing factors of the rainfall sites. This results
in a total of 23 parameters for the developed
model. The ratio of observed cumulative rainfall
at Clifton Falls to the corresponding rainfall at the
Dasher for historical events is not consistent, and
varies significantly from one event to another.
This indicates the high variability of the spatial
distribution of rainfall events over the Kakanui
catchment. As these rainfall events were used in
the model calibration, it was difficult to obtain the
correct transfer function without proper
accounting for the spatial distribution of rainfall over the whole watershed. However, the model,
in general, performed satisfactory, given the
difficulty in representing the spatial variability of
the rainfall events. The model was capable of
simulating the flood hydrographs of several
events which were incorporated in its calibration,
but did not perform well with others. The model
was able to simulate well the flows of a flood
event which was not included in its calibration.
Moreover, in applying the derived model for a
real case event which occurred most recently on
30 July 2007, the model was able to forecast very
closely the peak flow, but the whole flow
hydrograph was not forecasted as good
Generalized magneto-thermoelasticity in a perfectly conducting medium
AbstractA model of the equations of generalized magneto-thermoelasticity in a perfectly conducting medium is given. The formulation is applied to generalizations, Lord–Shulman theory with one relaxation time and the Green–Lindsay theory with two relaxation times, as well as to the coupled theory.Laplace transforms and Fourier transforms techniques are used to get the solution. The resulting formulation is used to solve a specific two-dimensional problem. The inverses of Fourier transforms are obtained analytically.Laplace transforms are obtained using the complex inversion formula of the transform together with Fourier expansion techniques.Numerical results for the temperature distribution, thermal stress and displacement components are represented graphically. A comparison was made with the results predicted by the three theories
Power Sharing Method Based on Droop Control for Three-Phase UPS Systems
The main objective of this paper is to improve the power sharing capability and to achieve synchronization between three-phase Uninterruptible power supply (UPS) units in the presence of load interruption. This paper presents a droop-controlled scheme in such a way that the computation of the instantaneous value of the active power and the reactive power are taken as feedback signals to the frequency and voltage restoration control system. The restored frequency and voltage are introduced to voltage controller circuit, which produces a suitable control signal to sinusoidal pulse width modulation circuit (SPWM). Thus producing a suitable trigger pulses to the inverter gate in order to guarantee synchronization between three-phase UPS units. Simulation of two UPS units with the same ratings (4 KW) are carried out using MATLAB. The results show the effectiveness of the proposed control system in achieving synchronization and improving the power sharing capability in the presence of load interruption. Keywords: Uninterruptible power supply; power sharing; parallel operation; droop control. DOI: 10.7176/JETP/9-4-02 Publication date: April 30th 201
FORMULATION AND CHARACTERIZATION OF ETHOSOMES BEARING VANCOMYCIN HYDROCHLORIDE FOR TRANSDERMAL DELIVERY
Objectives: To investigate and evaluate the transdermal delivery of ethosomes bearing vancomycin hydrochloride, a glycopeptide antibiotic with a relatively high molecular weight (1485.7Da).Methods: Vancomycin loaded ethosomes were prepared by cold method technique and characterized for vesicular shape, vesicular size, entrapment efficiency, zeta potential, in vitro drug permeation, microbiological assay against methicillin resistant Staphylococcusaureus (MRSA) and stability.Results: Microscopic examinations suggested ethosomes as unilamellar spherical vesicles. Vesicle size, entrapment efficiency and zeta potential values were depending on concentration of membrane components. Ethosomal formula having 1% phospholipid, 45% ethanol and 10% propylene glycol (F13) showed the smallest mean particle size (71.60nm±17.6) and highest transdermal flux (414.7 µg/cm2. hr) across hairless rat skin which was 72.67 times drug solution. The results obtained from microbiological assay suggested that the minimum inhibitory concentration (MIC) is affected by surface charge of ethosomes. The optimized formula on storage at 4°C for 90 days retained 89.82%±1.00 of initial drug content.Conclusions: The results collectively suggest that ethosomes are efficient carrier for transdermal delivery of vancomycin hydrochloride
Scaling Up Manufacturing of Edible Coatings for Food
One of the most important methods for prolonging the shelf life of fruits and vegetables is edible coatings. The manufacture of the edible coating was tested in the laboratory before being scaled up to the industrial scale which is a procedure for applying, which applies the same process to different output volumes. One of the most crucial processes in the manufacturing of edible coatings is mixing. The equipment needed to scale up the production of edible solutions for food coating was also assessed. The results of the measurements revealed that scaling up mixing is based upon constant power/volume, equal blend duration, and adjusting the impeller/tank (D/T) diameter ratio was possible. A four-blade impeller was utilized to homogenize 1% carrageenan solutions at 70°C. Also, mixing parameters (Power number, Blend number, and Pumping number) were determined at different D/T ratios. Cost-effective pipe diameter and optimum pipe diameter per unit length were also determined
A Computerized Tomographic Data Analysis System to Evaluate the Dental Implant Surface Roughness
AbstractDental implants have been progressively used in the recent years to support and retain dental prosthesis. Implant surface roughness has been suggested as a crucial factor in implant osseointegration and long term survival of the implant and prosthesis, where a key factor for the success or failure of dental implants is the manner in which stresses are transferred to surrounding bone. In this study completely edentulous patients were rehabilitated by implant retained over denture in which two implant systems with different surface roughness were used. Peri implant bone density in Hounsfield Units (HU) was evaluated by analyze Computerized Tomographic (CT) images to judge the behavior of an implant system under functional loading, where DICOM raw data was imported into the analysis proposed system to correlate the bone density regarding to the HU values. Results are compared with clinical readings and previous findings, which it showed that there is a difference in peri implant bone density around regularly patterned and randomly patterned implant surfaces
Evaluation of regulatory T cells in obese asthmatic children
Background: Asthma is an airway inflammatory disorder with functional and structural changes. Regulatory T (T reg) cells are important in controlling immune responses. The study was aimed to investigate the frequency of Treg cells in obese asthmatic children, in comparison to non-obese asthmatics and healthy matched controls .Methods: In addition to anthropometric and body mass index (BMI) assessment, peripheral blood samples from healthy control subjects (n = 30) and asthmatic obese (n=30) and asthmatic non-obese children (n=30) were examined for serum IgE, eosinophils counts, and flowcytometric measurement of CD4+CD25+CD127 low/neg- T cells. Pulmonary function testing was performed for asthmatic children . Results: Obese asthmatics showed significantly higher levels of serum IgE and CD4+CD25+CD127 low/neg- T cells as compared to healthy controls (p<0.001, 0.001, respectively) while comparable numbers of T reg cells were found among obese and non-obese asthmatic children. Asthmatics receiving inhaled corticosteroids (ICS) showed higher percentages of CD4+CD25+CD127 low/neg- T cells than the non-receivers (median 11.8% vs 8.8%, p <0.001). No significant correlations were found between Treg and age, eosinophil percentage, total serum IgE, pulmonary functions, or BMI and its Z score . Conclusion: Our study demonstrates an increased frequency of Treg cells in asthmatic children compared to controls with possible association with the use of ICS but not with obesity. Small sample size and lack of obese non-asthmatic group are the main points of limitation in our study
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