560 research outputs found
Hydrogeology and Physico-Chemical Quality Assessment of Groundwater in Oke-Oyi Area and Environs, Kwara State, Nigeria
An appraisal of the groundwater potential as well as its potability in Oke-Oyi area and its environs was undertaken. This was done in order to provide information on the evaluation of groundwater system in the area as well as on the physico-chemical quality of the groundwater for domestic and Agricultural purposes. The Study entails analysing pumping test data in order to compute the hydraulic characteristics of seven boreholes in the area. Fifteen groundwater samples were also collected from boreholes and hand-dug wells in the area and analysed for their physical and chemical properties.The two aquifer units in the area are weathered overburden aquifer and fractured crystalline aquifer. The boreholes tapping these aquifers have yields that range from 43.2m3/day to 103.7 m3/day with a mean value of 58.01 m3/day, hydraulic conductivity values range between 1.17×10-1 m/day and 8.60 ×10-2 m/day with a mean value of 6.27×10-2 m/day. Transmissivity varies from 0.95m2/day to 3.16 m2/day with an average value of 1.77 m2/day. The storage coefficient (S) calculated shows values that range from 0.619 to 1.765 with a mean value of 1.238. Results obtained from the physico chemical analysis of the groundwater in the area shows that the physical parameters such as colour, taste and odour are within the acceptable limits of WHO (2006). Also, the major ions analysed are Ca, Mg, Na, K, Fe, SO4, NO3, Cl, CO3 and HCO3 and are all below the acceptable limits of WHO (2006). Hence the groundwater of the area is largely characterised as Mg-HCO3-Cl and Mg-HCO3.The groundwater of the area has a low-medium salinity hazard and low sodium hazard, indicating that the groundwater is good for Agricultural purposes.The groundwater has a high recharge potential due to its low storage capacity. Also the groundwater is potable for domestic and Agricultural purposes, based on the physical and chemical parameters of the groundwater analysed which are within the acceptable limits of WHO as well as low-medium salinity hazard of the groundwater. Keywords:Hydrogeology. Groundwater Potential and potability. Oke-Oyi area and its environs. Physico-Chemical. Nigeri
Modelling of Fatigue Failure for Plasma Coated Members Using Artificial Intelligence Technique
Coating materials in form of powder such as Magnesium Zirconate, Aluminum Bronze and Molybdenum were mixed in different portions and sprayed on steel specimen to find the fatigue properties of steel using plasma technique. The effect of coating mixture on the number of cycles needed for failure under different loads was done experimentally. A cyclic loading was applied to it repeatedly until failure occurs. The results were compared with those for the same specimen without coating. The results were then modelled using Artificial Intelligence Technique then optimized for maximum cycles of coated substance failure. The results showed significant improvement to the specimen’s resistance to failure with coating. Further, models were developed out of the experimental data and tested for accuracy and gave satisfactory results. However, the time consumed by the GA method was greater than that consumed by the same software for the ANN model development.Also, sensitivity analysis showed that the key effect for the variables studied was for the load while the least effect was for the Molybdenum mixture. On the other hand, using GA method, the importance of variables was maximum for the load and minimum for Magnesium oxide and Zirconate oxide mixture Further, using the correlation method, there was strong negative (i.e. inverse relationship) correlation between the number of cycles and load and weak with Magnesium oxide and Zirconate oxide mixture while strong positive correlation was shown with Molybdenum and least positive for Aluminum Copper Balance. Keywords: Artificial neural network, modeling, Plasma coating, fatigue failure
A Quantitative Comparison of SMC, LMC, and Milky Way UV to NIR Extinction Curves
We present an exhaustive, quantitative comparison of all of the known
extinction curves in the Small and Large Magellanic Clouds (SMC and LMC) with
our understanding of the general behavior of Milky Way extinction curves. The
R_V dependent CCM relationship and the sample of extinction curves used to
derive this relationship is used to describe the general behavior of Milky Way
extinction curves. The ultraviolet portion of the SMC and LMC extinction curves
are derived from archival IUE data, except for one new SMC extinction curve
which was measured using HST/STIS observations. The optical extinction curves
are derived from new (for the SMC) and literature UBVRI photometry (for the
LMC). The near-infrared extinction curves are calculated mainly from 2MASS
photometry supplemented with DENIS and new JHK photometry. For each extinction
curve, we give R_V = A(V)/E(B-V) and N(HI) values which probe the same dust
column as the extinction curve. We compare the properties of the SMC and LMC
extinction curves with the CCM relationship three different ways: each curve by
itself, the behavior of extinction at different wavelengths with R_V, and
behavior of the extinction curve FM fit parameters with R_V. As has been found
previously, we find that a small number of LMC extinction curves are consistent
with the CCM relationship, but majority of the LMC and all of the SMC curves do
not follow the CCM relationship. For the first time, we find that the CCM
relationship seems to form a bound on the properties of all of the LMC and SMC
extinction curves. This result strengthens the picture of dust extinction
curves exhibit a continuum of properties between those found in the Milky Way
and the SMC Bar. (abridged)Comment: 18 pages, 10 figures, ApJ in pres
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Bladder perivascular epithelioid cell neoplasm: The importance of immunohistochemistry in the diagnosis of an unusual neoplasm.
Perivascular epithelioid cell neoplasms represent a group of uncommon mesenchymal tumours with as yet undiscovered benign counterpart. Although perivascular epithelioid cell neoplasms have been described arising in most organ systems as well as in soft tissue and bone, only a small number of perivascular epithelioid cell neoplasms have been reported in the bladder. To date, there is no agreed system for predicting the behaviour of these tumours. We describe a case of a perivascular epithelioid cell neoplasm of the bladder arising in a 57-year-old male and initially diagnosed on biopsy and present a review of the literature focussing on the pathological differential diagnosis and the importance of key histological features in conjunction with a broad immunohistochemical panel. This case report highlights the key features of bladder perivascular epithelioid cell neoplasms that distinguishes these rare neoplasms from other bladder lesions
Identification of the Red Supergiant Progenitor of Supernova 2005cs: Do the Progenitors of Type II-P Supernovae Have Low Mass?
The stars that end their lives as supernovae (SNe) have been directly
observed in only a handful of cases, due mainly to the extreme difficulty in
identifying them in images obtained prior to the SN explosions. Here we report
the identification of the progenitor for the recent Type II-plateau
(core-collapse) SN 2005cs in pre-explosion archival images of the Whirlpool
Galaxy (M51) obtained with the Hubble Space Telescope (HST) Advanced Camera for
Surveys (ACS). From high-quality ground-based images of the SN from the
Canada-France-Hawaii Telescope, we precisely determine the position of the SN
and are able to isolate the SN progenitor to within 0".04 in the HST/ACS
optical images. We further pinpoint the SN location to within 0".005 from
HST/ACS ultraviolet images of the SN, confirming our progenitor identification.
From photometry of the SN progenitor obtained with the pre-SN ACS images, and
also limits to its brightness in pre-SN HST/NICMOS images, we infer that the
progenitor is a red supergiant star of spectral type K0--M3, with initial mass
7--9 Msun. We also discuss the implications of the SN 2005cs progenitor
identification and its mass estimate. There is an emerging trend that the most
common Type II-plateau SNe originate from low-mass supergiants 8--15 Msun.Comment: Submitted to ApJ. A high resolution version can be found at
http://astron.berkeley.edu/~weidong/sn05cs.p
Hydrophobicity modulated antibacterial small molecule eradicates biofilm with potent efficacy against skin-infections
The role of molecular arrangement of hydrophobic and hydrophilic groups for designing membrane-active molecules remains largely ambiguous. To explore this aspect, herein we report a series of membrane-active small molecules by varying the spatial distribution of hydrophobic groups. The two terminal amino groups of linear triamines such as diethylene triamine, bis(trimethylene)triamine and bis(hexamethylene)triamine were conjugated with cationic amino acids bearing variable side chain hydrophobicity (such as diaminobutyric acid, ornithine and lysine). The hydrophobicity was also modulated through conjugation of different long chain fatty acids with the central secondary amino group of the triamine. Molecules with constant backbone hydrophobicity displayed an enhanced antibacterial activity and decreased hemolytic activity upon increasing the side chain hydrophobicity of amino acids. On the other hand, increased hydrophobicity in the backbone introduced a slight hemolytic activity but a higher increment in antibacterial activity resulting in better selective antibacterial compounds. The optimized lead compound derived from structure-activity-relationship (SAR) studies was the dodecanoyl analogue of lysine series of compounds consisting of bis(hexamethylene)triamine as the backbone. This compound was active against various Gram-positive and Gram-negative bacteria at a low concentration (MIC ranged between 3.1-6.3 µg/mL) and displayed low toxicity towards mammalian cells (HC50 = 890 µg/mL and EC50 against HEK = 85 µg/mL). Additionally, it was able to kill metabolically inactive bacterial cells and eradicate preformed biofilms of MRSA. This compound showed excellent activity in a mouse model of skin-infection with reduction of ~4 log MRSA burden at 40 mg/kg dose without any sign of skin-toxicity even at 200 mg/kg. More importantly, it revealed potent efficacy in an ex-vivo model of human skin-infection (with reduction of 85% MRSA burden at 50 μg/mL), which indicates great potential of the compound as an antibacterial agent to treat skin-infections
Cerium (IV) Oxide Reinforced Lithium-Borotellurite Glasses: A Characterization Study Through Physical, Optical, Structural and Radiation Shielding Properties
The purpose of this study was to characterize the structural, optical, and physical properties of various kinds of glasses based on the 50TeO2–30B2O3-(20-x)Li2O-xCeO2 system (x = 0, 0.5, 1, 2, 3, 4, 5, 10, 15, 20). Consequently, ten glass samples were produced by melting-annealing. Calculations of the densities of the synthesized glasses were performed using the Archimedes technique. The sample's structural, optical, physical, and radiation interaction properties were determined using XRD analysis, Raman spectroscopy, and advanced modelling techniques with FLUKA code, yielding optical band gap, refractive index, and Urbach energy values. By increasing the CeO2 reinforcement from 0 to 20 mol %, the glass densities rose from 4.0614 to 4.7519 g cm−3. The transmittance spectra of TBLC glasses were found in the range of 200–1100 nm. Our findings showed that the lowest Urbach energy belonged to the TBLC1 sample, and the highest Urbach energy belonged to the TBLC20 sample. When the CeO2 ratio was raised, the optical transmittance and absorption characteristics changed nearly monotonically, suggesting that these qualities may be calculated and controlled using the CeO2 additive, as shown in this experiment. By substituting CeO2 for Li2O inside the structure, it was possible to substantially enhance the optical band gap. Additionally, at simulated energies greater than 0.02 MeV, the gamma-ray linear attenuation coefficient rises monotonically with CeO2 reinforcement. Consequently, linear attenuation coefficients were reported as 125.843 cm−1, 127.601 cm−1, 129.211 cm−1, 132.312 cm−1, 135.166 cm−1, 138.705 cm−1, 141.288 cm−1, 156.690 cm−1, 172.393 cm−1, 186.811 cm−1 for TBLC0, TBLC0.5, TBLC1, TBLC2, TBLC3, TBLC4, TBLC5, TBL10, TBLC15 and TBLC20 at 0.015 MeV, respectively. It can be concluded that combination of high-concentration CeO2 and TeO2–B2O3 glass is an excellent synergetic tool for combining structural, optical, and radiation properties when combined with other materials. © 2021 Elsevier Ltd and Techna Group S.r.l.The research activity is supported by Eskisehir Osmangazi University, Scientific Research Council with grant number 202019D20
Application of artificial intelligence techniques for automated detection of myocardial infarction: A review
Myocardial infarction (MI) results in heart muscle injury due to receiving
insufficient blood flow. MI is the most common cause of mortality in
middle-aged and elderly individuals around the world. To diagnose MI,
clinicians need to interpret electrocardiography (ECG) signals, which requires
expertise and is subject to observer bias. Artificial intelligence-based
methods can be utilized to screen for or diagnose MI automatically using ECG
signals. In this work, we conducted a comprehensive assessment of artificial
intelligence-based approaches for MI detection based on ECG as well as other
biophysical signals, including machine learning (ML) and deep learning (DL)
models. The performance of traditional ML methods relies on handcrafted
features and manual selection of ECG signals, whereas DL models can automate
these tasks. The review observed that deep convolutional neural networks
(DCNNs) yielded excellent classification performance for MI diagnosis, which
explains why they have become prevalent in recent years. To our knowledge, this
is the first comprehensive survey of artificial intelligence techniques
employed for MI diagnosis using ECG and other biophysical signals.Comment: 16 pages, 8 figure
Reversibility of liver fibrosis
Liver fibrosis, and its end stage cirrhosis are a major cause of morbidity and mortality and therapeutic options are limited. However, the traditional view of liver disease as an irreversible process is obsolete and it is now evident that the development of liver fibrosis is a dynamic and potentially bidirectional process. Spontaneous resolution of scarring is seen in animal models of liver fibrosis and in human trials in which the stimuli responsible for chronic or repeated hepatic inflammation is successfully removed. Key players in the process are hepatic stellate cells, macrophages, MMPs and their inhibitors Timps. It is also evident that in advanced fibrotic liver disease, specific histological features define what is currently described as "irreversible" fibrosis. This includes the development of paucicellular scars enriched in extensively cross-linked matrix components, such as fibrillar collagen and elastin. Our recent work has focused on the role of macrophage metalloelastase (MMP-12) in the turnover of elastin in reversible and irreversible models of fibrosis. We have shown that elastin turnover in liver injury and fibrosis is regulated by macrophages via Mmp-12 expression, activity and ratio to its inhibitor Timp-1. Failure of elastin degradation, together with increased deposition leads to accumulation of elastin in the fibrotic scars
Natural Course and Treatment of Pancreatic Exocrine Insufficiency in a Nationwide Cohort of Chronic Pancreatitis
Objectives Pancreatic exocrine insufficiency (PEI) is a common complication of chronic pancreatitis. However, little is known about the natural course of PEI and the effect of pancreatic enzyme replacement therapy on symptoms. The aim of this study was to evaluate the natural course and treatment of PEI in a nationwide cohort of patients with chronic pancreatitis. Methods Patients with chronic pancreatitis were selected from the multicenter Dutch Chronic Pancreatitis Registry. Patients were classified in 3 groups: Definite PEI, potential PEI, and no PEI. Definite PEI and no PEI were compared regarding the course of disease, symptoms, treatment, and quality of life. Results Nine hundred eighty-seven patients were included from 29 centers, of which 304 patients (31%) had definite PEI; 451 (46%), potentially PEI; and 232 (24%), no PEI. Patients with definite PEI had significantly more malabsorption symptoms, a lower body mass index, and aberrant defecation. Lowered quality of life was not independently associated with PEI. Of the PEI patients using pancreatic enzyme replacement therapy, 47% still reported steatorrhea. Conclusions Pancreatic exocrine insufficiency is associated with malabsorption symptoms and a lower body mass index. Some form of pancreatic enzyme replacement therapy is reasonably effective in alleviating malabsorption symptoms, but improvement of treatment is needed
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