509 research outputs found

    Kernels for Grassmann flops

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    We develop a generalization of the QQ-construction of the first author, Diemer, and the third author for Grassmann flips. This generalization provides a canonical idempotent kernel on the derived category of the associated global quotient stack. The idempotent kernel, after restriction, induces a semi-orthogonal decomposition which compares the flipped varieties. Furthermore its image, after restriction to the geometric invariant theory semistable locus, "opens" a canonical "window" in the derived category of the quotient stack. We check this window coincides with the set of representations used by Kapranov to form a full exceptional collection on Grassmannians

    Occurrence of Uranium in Groundwater from Cuddalore District Tamil Nadu Aided by Geospatial and Statistical Techniques

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    An attempt has been made to examine uranium distribution in groundwater from Cuddalore district, Tamil Nadu, India. Groundwater occurs under porous sedimentary, fractured, and weathered hard rock formations ranging in age from recent sediments to the oldest Archean formations. A total of 186 groundwater samples were collected during Pre- Monsoon (May) and Post-monsoon (January) and analyzed for major cations, anions, and uranium using standard procedures. Major anions and cations follow the order Cl- >H4SiO4>HCO3- >NO3- > Na+> Ca2+> Mg2+>K+>SO42- > F-> PO43- irrespective of seasons. Uranium in groundwater ranges from 0.1 micro gram per liter (µg/l ) to 24.67 µg/l with average 1.82 µg/l. The spatial representation maps isolated areas of higher and lower uranium and statistical analysis inferred uranium sources to the groundwater environment

    Manufacturing, Testing of Polymer Nanocomposite and Analysis of Tennis Racket Frame

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    The modern days, the game of tennis expects high levels of performance from every international tennis players. The performance of every tennis player based on the tennis racket and playing conditions. The evolution of the tennis racket, with respect to both design and materials (tennis racket strings and grips) developed lots of new tennis racket frames. The tennis racket required to change in recent years as a result of lightweight, stiffer rackets for better performance. The paper discusses the manufacturing, testing, structural and modal analysis of four ratios of Nylon6,6/MWNT new polymer nanocomposite material replacing excising composite materials to a tennis racket frame for better mechanical properties to enhanced performance of the tennis racket. Using universal testing machine test and calculate the various mechanical properties strength, modulus, impact, hardness, stiffness, toughness of the polymer nanocomposite. In the design, the tennis racket frame was designed of the shape, dimensions. After design part created the 3D model using by PRO/ENGINEER software. The 3D racket model can be export to ANSYS analysis software and incorporated with new polymer nanocomposite properties. The structural and model analysis was done

    Bumper catch of oil sardine Sardinella longiceps along Cuddalore coast

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    The oil sardine Sardinella longiceps constitutes the most important pelagic resource sustaining the marine fishery on the west coast of India. Two decades ago, the occurrence of this species along the east coast was considered sporadic and rare. In early eighties, there was report on the unusual landing of this species along Puducherry region. Over the years, there has been an increase in the landings of this species on the east coast especially along the Coromandal coast. In July 2008, there were reports in the local daily news papers that the oil sardine shoals were found to move towards the shore off Devanampattinam fishing village and small boys were also able to have easy access to the fish shoal who handpicked the sardines. Some fishes were also stranded and found dead on the beach. This occurrence is linked to upwelling phenomenon which brings the oxygen depleted cold water from the bottom of the sea due to churning by the water current

    Spectroscopic studies on monomers and dimers of thiaporphyrins

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    Synthesis and spectroscopic properties of porphyrin macrocycles with sulphur as the heteroatom in the porphyrin core have been studied. Electronic absorption spectra of these macrocycles show porphyrin-like behaviour with a strong Soret band and weakQ-bands. Substitution of the -NH groups of tetraphenylporphyrin (TPPH2) by sulphur causes a red shift of all the absorption bands and the magnitude of the red shift depends on the number of sulphur atoms substituted. Both the mono and dications of dithiaporphyrins (S2TPP) show larger bathochromic shifts ofQ-bands relative to TPPH2 indicating a stronger resonance interaction with the phenyl groups. A positive shift for both oxidation and reduction potentials is observed upon substitution of sulphur atoms. 1H NMR spectra of symmetrically substituted dithiaporphyrins show two sharp singlets for pyrrole protons and thiophene protons confirming the presence of a two-fold axis of symmetry. Only monothia derivatives (STPPH) form metal complexes [Ni(II), Cu(II)] and these metal complexes are five-coordinate with an apical chloride ligand. The water-soluble S2TPPS, prepared from sulphonating the para positions of phenyl rings shows extensive aggregation at high concentrations (> 10-4M). At low concentrations (≈ 10-610-7M), dimerisation can be induced by the addition of cations (K+, NH4+ ) and cation-crown ether complex. The induced red shifts upon dimerisation parallel findings reported for a variety of cofacial covalently linked porphyrin dimers

    RT-2 Detection of Quasi-Periodic Pulsations in the 2009 July 5 Solar Hard X-ray Flare

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    We present the results of an analysis of hard X-ray observations of the C2.7 solar flare detected by the RT-2 Experiment onboard the Coronas - Photon satellite. We detect hard X-ray pulsations at periods of ~12 s and ~15 s. We find a marginal evidence for a decrease in period with time. We have augmented these results using the publicly available data from the RHESSI satellite. We present a spectral analysis and measure the spectral parameters.Comment: 12 pages, 8 figures and 3 tables, accepted for publication in The Astrophysical Journa

    Effect of 17 α -methyl testosterone on sex reversal and growth of Nile tilapia (Oreochromis niloticus L., 1758)

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    The present study aims at developing a production of monosex population of all male Nile tilapia (Oreochromis niloticus) using 17α-methyltestosterone (17α-MT). Three treatments with a control (Control, T-1, T-2, and T-3) in triplicates were set up using completely randomized design (CRD). The control group diet was devoid of 17α–MT. The remaining groups T-1, T-2, T-3 and T-4 were fed with feed containing 50, 60 and 100 mg kg-1 of 17α –MT. Three days old fry were stocked at the rate of 300 nos per tank. The fry were fed with experimental diet for 21 days. After that it was shifted to FRP tanks. The maximum mean length and body weight was observed in T-2 is 80 ± 3.87 mm and 59.5 ± 7.4 mm respectively. Gonadal histology from 3 months reared O. niloticus for sex reversal was observed that 56.7 %, 83.3 %, 93.3 % and 90 % males respectively. The highest male population of 93.3% males was produced from treated groups of (T-2) 60 mg kg-1 17 α-MT

    Converse mode piezoelectric coefficient for lead zirconate titanate thin film with interdigitated electrode

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    The use of interdigitated electrodes (IDEs) in conjunction with ferroelectric thin films shows many attractive features for piezoelectric MEMS applications. In this work, growth of {1 0 0}-textured lead zirconate titanate (PZT) thin films was achieved on insulating MgO buffered, oxidized silicon substrates. IDEs were fabricated by lift-off techniques and cantilevers were formed by dicing. The deflection upon application of a sweeping voltage was measured as large signal response in parallel to the ferroelectric polarization (PV loop). Likewise, the small signal piezoelectric response was measured in parallel to the capacitance-voltage (CV) measurement. In this way, a complete picture of the ferroelectric-piezoelectric element was obtained. From the deflection, the in-plane piezoelectric stress in the PZT thin film was derived and, from this, the effective piezoelectric coefficients. For the latter, two types were defined: an engineering type corresponding to the average value along the IDE, which can directly be compared to coefficient of a parallel plate electrode (PPE) capacitor and a second one that approximately yields the idealized coefficient governing between the electrode fingers. The IDE structures were experimentally compared with PPE structures of identical film thickness. The resulting coefficients were of opposite sign, as expected. In spite of a much better polarization loop, the IDE device showed a lower average piezoelectric stress. The estimated peak value between the fingers was about the same as in the PPE device, corresponding to about 20 C m(-2). Nevertheless, the result is very promising for cases where compressive piezoelectric stresses are required and for preventing cracking due to large piezoelectric tensile stresses in PPE systems

    Multicenter, prospective cohort study of oesophageal injuries and related clinical outcomes (MUSOIC study)

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    Objective: To identify prognostic factors associated with 90-day mortality in patients with oesophageal perforation (OP), and characterize the specific timeline from presentation to intervention, and its relation to mortality. Background: OP is a rare gastro-intestinal surgical emergency with a high mortality rate. However, there is no updated evidence on its outcomes in the context of centralized esophago-gastric services; updated consensus guidelines; and novel non-surgical treatment strategies. Methods: A multi-center, prospective cohort study involving eight high-volume esophago-gastric centers (January 2016 to December 2020) was undertaken. The primary outcome measure was 90-day mortality. Secondary measures included length of hospital and ICU stay, and complications requiring re-intervention or re-admission. Mortality model training was performed using random forest, support-vector machines, and logistic regression with and without elastic net regularisation. Chronological analysis was performed by examining each patient’s journey timepoint with reference to symptom onset. Results: The mortality rate for 369 patients included was 18.9%. Patients treated conservatively, endoscopically, surgically, or combined approaches had mortality rates of 24.1%, 23.7%, 8.7%, and 18.2%, respectively. The predictive variables for mortality were Charlson comorbidity index, haemoglobin count, leucocyte count, creatinine levels, cause of perforation, presence of cancer, hospital transfer, CT findings, whether a contrast swallow was performed, and intervention type. Stepwise interval model showed that time to diagnosis was the most significant contributor to mortality. Conclusion: Non-surgical strategies have better outcomes and may be preferred in selected cohorts to manage perforations. Outcomes can be significantly improved through better risk-stratification based on afore-mentioned modifiable risk factors
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