Non destructive inspection of plates using frequency measurements

This paper examines the use of natural frequency measurements and energy formulation of vibration theory to detect damage present in a structure. The extent of change in natural frequencies of the structure due to damage, which is highly dependent on the location and size of damage, is used to detect and characterise damage. An analytical solution to detect and characterise damage in plates from just change in natural frequencies is presented here for the first time. Damage is modelled as a spring with finite stiffness which is less than that of the undamaged structure. Using the strain energies stored in the plate and that of spring, calculated from discrete values of deflection mode shapes, the location and size of the damage is determined. The applicability of this approach is demonstrated through a numerical study, where the location and size of through thickness centre cracks in simply supported plates is deduced with greater than 95 percent accuracy

FAST CHIRAL HPLC PROCEDURE FOR THE SIMULTANEOUS DETERMINATION OF DROPROPIZINE ENANTIOMERS AND ITS NONPOLAR IMPURITY IN RAW MATERIAL AND PHARMACEUTICAL FORMULATION

Objective: Levodropropizine is a novel antitussive drug, which occurs as enantiomers. They are levodropropizine (2S) [LDP] and dextrodropropizine (impurity A) (2R) [DDP]. An isocratic chiral high performance liquid chromatographic (Normal phase HPLC) method has been developed and validated for simultaneous determination of dropropizine enantiomers along with non-polar impurity-B, (1-phenyl piperazine) [1-PP] in raw material and in dosage forms. Methods: The compounds were separated on chiral stationary phase (CSP) Chiralpak AD-H column, with a mixture of n-hexane, anhydrous ethanol, diethyl amine (DEA) in the ratio of 55:45:0.1 v/v as mobile phase at a flow rate of 1.4 ml/min. UV detection was performed at 254 nm. The method was validated for accuracy, precision, specificity, linearity, and sensitivity. The developed and validated method was successfully used for quantitative analysis of commercially available Tablets. Results: Total chromatographic analysis time per sample was ~5 min. with 1-PP, levodrpropizne, dextropropizine eluting with retention times of 2.5 min., 3.05 min., and 3.66 min., respectively. Validation studies revealed the method is specific, rapid, reliable and reproducible for levodropropizne and its impurity A and non chiral impurity B. Calibration plots were linear over the concentration ranges 0.5-5 µg/ml and 0.5-5 µg/ml for levodropropizine and dextrodropropizine respectively. Conclusion: The high recovery and low relative standard deviation confirm the suitability of the method for determination of dropropizine compounds in commercial tablets

A Broad Search for Counterrotating Gas and Stars: Evidence for Mergers and Accretion

We measure the frequency of bulk gas-stellar counterrotation in a sample of 67 galaxies drawn from the Nearby Field Galaxy Survey, a broadly representative survey of the local galaxy population down to M_B-15. We detect 4 counterrotators among 17 E/S0's with extended gas emission (24% +8 -6). In contrast, we find no clear examples of bulk counterrotation among 38 Sa-Sbc spirals, although one Sa does show peculiar gas kinematics. This result implies that, at 95% confidence, no more than 8% of Sa-Sbc spirals are bulk counterrotators. Among types Sc and later, we identify only one possible counterrotator, a Magellanic irregular. We use these results together with the physical properties of the counterrotators to constrain possible origins for this phenomenon.Comment: 19 pages, 4 figures, AJ, accepte

The Fueling Diagram: Linking Galaxy Molecular-to-Atomic Gas Ratios to Interactions and Accretion

To assess how external factors such as local interactions and fresh gas accretion influence the global ISM of galaxies, we analyze the relationship between recent enhancements of central star formation and total molecular-to-atomic (H2/HI) gas ratios, using a broad sample of field galaxies spanning early-to-late type morphologies, stellar masses of 10^(7.2-11.2) Msun, and diverse stages of evolution. We find that galaxies occupy several loci in a "fueling diagram" that plots H2/HI vs. mass-corrected blue-centeredness, a metric tracing the degree to which galaxies have bluer centers than the average galaxy at their stellar mass. Spiral galaxies show a positive correlation between H2/HI and mass-corrected blue-centeredness. When combined with previous results linking mass-corrected blue-centeredness to external perturbations, this correlation suggests a link between local galaxy interactions and molecular gas inflow/replenishment. Intriguingly, E/S0 galaxies show a more complex picture: some follow the same correlation, some are quenched, and a distinct population of blue-sequence E/S0 galaxies (with masses below key transitions in gas richness) defines a separate loop in the fueling diagram. This population appears to be composed of low-mass merger remnants currently in late- or post-starburst states, in which the burst first consumes the H2 while the galaxy center keeps getting bluer, then exhausts the H2, at which point the burst population reddens as it ages. Multiple lines of evidence suggest connected evolutionary sequences in the fueling diagram. In particular, tracking total gas-to-stellar mass ratios within the diagram provides evidence of fresh gas accretion onto low-mass E/S0s emerging from central starbursts. Drawing on a comprehensive literature search, we suggest that virtually all galaxies follow the same evolutionary patterns found in our broad sample.Comment: 24 pages, 11 figures (table 4 available at http://user.physics.unc.edu/~dstark/table4_csv.txt), accepted for publication in Ap

Synthesis, crystal structure and magnetic properties of a polymeric copper(II) schiff-base complex having binuclear units covalently linked by isonicotinate ligands

The polynuclear copper(II) complex [{Cu2L(O2CC5H4N)}·C2H5OH]x (1), where H3L is a 1:2 Schiff base derived from 1,3-diaminopropan-2-ol and salicylaldehyde, has been prepared and structurally characterized. The structure consists of a one-dimensional zigzag chain in which the binuclear [Cu2L]+ units are covalently linked by isonicotinate ligands to give a syndiotactic arrangement of the copper ions protruding outside the chain. In the basic unit, the copper(II) centres are bridged by an alkoxo and a carboxylato ligand, giving a Cu···Cu distance of 3.492(3) Å and a Cu-O-Cu angle of 130.9(2)° . While one copper centre has a square-planar geometry, the other copper is squarepyramidal with the pyridine nitrogen being the axial ligand. The visible electronic spectrum of 1 shows a broad d-d band at 615 nm. The complex shows a rhombic X-band EPR spectral pattern in the polycrystalline phase at 77 K. Magnetic susceptibility measurements in the temperature range 22 to 295 K demonstrate the antiferromagnetic behaviour of 1. A theoretical fit to the magnetic data is based on a model assuming 1 as an equimolar mixture of copper atoms belonging to an antiferromagnetically coupled one-dimensional Heisenberg chain with the other copper atoms outside the chain behaving like paramagnetic centres

On generalizations of the Pompeiu functional equation

In this paper, we determine the general solution of the functional equations f(x+y+xy)=p(x)+q(y)+g(x)h(y),     (∀x,y∈ℜ*) and f(ax+by+cxy)=f(x)+f(y)+f(x)f(y),     (∀x,y∈ℜ) which are generalizations of a functional equation studied by Pompeiu. We present a method which is simple and direct to determine the general solutions of the above equations without any regularity assumptions

Co-infection of Yellowtip Halfbeak Fish (Hemiramphus marginatus) with Isopod and Copepod Parasites from the Coromandal Coast, India

Parasitic fish diseases constitute one of the most important problems in fisheries sector. Among fish parasites, cymothoids are obligatory parasites, infesting mostly commercially important fishes. They are protandric hermaphrodites and blood suckers, living on the skin, gill filaments, or in the mouth of the fishes. These parasites retard growth and cause emaciation followed by death. Pathological conditions resulting from parasitic diseases assume high magnitude of epidemics under crowded and other unnatural conditions among fish.Isopod parasite of the family Cymothoidae under order Beloniformes have been reported from about 350 fish species and over 80% of these occurrence are from tropical and subtropical seas, majority being from the Indo-Malaysian archipelago (Lester, 1995)

Two more disk galaxies with global gas counterrotation

We report a discovery of extended counterrotating gaseous disks in early-type disk galaxies NGC 2551 and NGC 5631. To find them, we have undertaken complex spectral observations including integral-field spectroscopy for the central parts of the galaxies and long-slit deep spectroscopy to probe the external parts. The line-of-sight velocity fields have been constructed and compared to the photometric structure of the galaxies. As a result, we have revealed full-size counterrotating gaseous disks, the one coplanar to the stellar disk in NGC 2551 and the other inclined to the main stellar disk in NGC 5631. We suggest that we observe the early stages of minor-merger events which may be two different stages of the process of lenticular galaxy formation in rather sparse environments.Comment: 8 pages, 8 EPS figures, accepted for publication in Ap

An extended star formation history in an ultra-compact dwarf

There has been significant controversy over the mechanisms responsible for forming compact stellar systems like ultra-compact dwarfs (UCDs), with suggestions that UCDs are simply the high-mass extension of the globular cluster population, or alternatively, the liberated nuclei of galaxies tidally stripped by larger companions. Definitive examples of UCDs formed by either route have been difficult to find, with only a handful of persuasive examples of stripped-nucleus-type UCDs being known. In this paper, we present very deep Gemini/GMOS spectroscopic observations of the suspected stripped-nucleus UCD NGC 4546-UCD1 taken in good seeing conditions (<0.7 arcsec). With these data we examine the spatially resolved kinematics and star formation history of this unusual object. We find no evidence of a rise in the central velocity dispersion of the UCD, suggesting that this UCD lacks a massive central black hole like those found in some other compact stellar systems, a conclusion confirmed by detailed dynamical modelling. Finally, we are able to use our extremely high signal-to-noise spectrum to detect a temporally extended star formation history for this UCD. We find that the UCD was forming stars since the earliest epochs until at least 1-2 Gyr ago. Taken together these observations confirm that NGC 4546-UCD1 is the remnant nucleus of a nucleated dwarf galaxy that was tidally destroyed by NGC 4546 within the last 1-2 Gyr.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat