Focusing a fountain of neutral cesium atoms with an electrostatic lens triplet

An electrostatic lens with three focusing elements in an alternating-gradient configuration is used to focus a fountain of cesium atoms in their ground (strong-field-seeking) state. The lens electrodes are shaped to produce only sextupole plus dipole equipotentials which avoids adding the unnecessary nonlinear forces present in cylindrical lenses. Defocusing between lenses is greatly reduced by having all of the main electric fields point in the same direction and be of nearly equal magnitude. The addition of the third lens gave us better control of the focusing strength in the two transverse planes and allowed focusing of the beam to half the image size in both planes. The beam envelope was calculated for lens voltages selected to produced specific focusing properties. The calculations, starting from first principles, were compared with measured beam sizes and found to be in good agreement. Application to fountain experiments, atomic clocks, and focusing polar molecules in strong-field-seeking states is discussed.Comment: 8 pages 10 figure

Osmoregulatory ability of Penaeus monodon (fabricius) In relation to varying salinities

Adult Penaeus rnonodon osmoregulated well between salinities 3 and 45%0 for 24 and 48 hour duration with isosmotic points around = S18.5% and =S 23.520 respectively. A duration of 48 hr is essential for prawns to adjust to the new medium. Influence of eyestalk removal on osmolal concentration of haemo- lymph was studied. There was a significant decline in osmolal concentration in destalked prawns from 4 to 18hr after eyestalk surgery performance, but later recouping effect was seen. In destalked prawns when eyestalk extract was administered, the level of osmolal concentration did not decrease but always remained high throughout the experimental period. Probable reasons for such changes are discussed

Nonlinear dynamics in an alternating gradient guide for neutral particles

Neutral particles can be guided and focussed using electric field gradients that focus in one transverse direction and defocus in the other, alternating between the two directions. Such a guide is suitable for transporting particles that are attracted to strong electric fields, which cannot be guided using static fields. Particles are only transmitted if their initial positions and transverse speeds lie within the guide's phase space acceptance. Nonlinear forces are always present in the guide and can severely reduce this acceptance. We consider the effects of the two most important nonlinear forces, a term in the force that is cubic in the off-axis displacement, and a nonlinear term which couples together the two transverse motions. We use approximate analytical techniques, along with numerical methods, to calculate the influence of these nonlinear forces on the particle trajectories and on the phase space acceptance. The cubic term alters the focussing and defocussing powers, leading either to an increase or a decrease of the acceptance depending on its sign. We find an approximate analytical result for the phase space acceptance including this cubic term. Using a perturbation method we show how the coupling term leads to slow changes in the amplitudes of the transverse oscillations. This term reduces the acceptance when it reduces the focussing power, but has little influence when it increases that power. It is not possible to eliminate both nonlinear terms, but one can be made small at the expense of the other. We show how to choose the guide parameters so that the acceptance is optimized.Comment: 31 pages, 12 figure

Fluctuation in calcium levels in the exoskeleton, Muscle and haemolymph of Penaeus indicus, cultivated In a brackishwater pond

The calcium content in the exoskeleton of Penaeus indicus cultivated in a brackishwaterpond was found between 4 and 15%, which was low compared to other crustaceans. The haemolymph calcium was observed always at a higher level than the calcium in the pond water. Calcium content of pond water and haemolymph showed a direct relationship wiith the salinity. Relatively high levels of calcium in muscle and low levels in exoskeleton were observed in June, the probable reasons for this abrupt fall in the values are discussed

Slowing and cooling molecules and neutral atoms by time-varying electric field gradients

A method of slowing, accelerating, cooling, and bunching molecules and neutral atoms using time-varying electric field gradients is demonstrated with cesium atoms in a fountain. The effects are measured and found to be in agreement with calculation. Time-varying electric field gradient slowing and cooling is applicable to atoms that have large dipole polarizabilities, including atoms that are not amenable to laser slowing and cooling, to Rydberg atoms, and to molecules, especially polar molecules with large electric dipole moments. The possible applications of this method include slowing and cooling thermal beams of atoms and molecules, launching cold atoms from a trap into a fountain, and measuring atomic dipole polarizabilities.Comment: 13 pages, 10 figures. Scheduled for publication in Nov. 1 Phys. Rev.

Stock assessment of the penaeid prawn Metapenaeus dobsoni (Miers) along the Indian coast

The annual prodiction of M. dobsoni showed an increasing trend with an annual average of 22 370 t during 1985-S9. It formed 15.7% of the penaeid prawn landings in the country. West coast contributed 69.9% to the annual yield of this prawn. Kerala ranked first (51.4%) in M. dobsoni production followed b;' Tamil Nadu. Shrimp trawl alone caught 54% of the landings. L«> and K were 139 mm and 2.4 for m«les, and 145 mm and 2.76 for females respectively. The instantaneous mortality coefficient (Z) ranged lietween 16,47 and 25.29 in males, and between 16.21 and 20.97 in females. Tlie natural mortality coefficient (M) was 2.3 for both the sexes. The yield per recruit (Yw/R) increased steadily to maximum values (MSY/R) in both the sexes at Emax ranging between 0.2 and 0.4. It marginally reduced at Ihe present E between 0.8 and 0.9 suggesting that the resource is overexploited and the current effort s far higher than the effort required to harvest optimum yields. Although the average annual catch by shrimp trawls (12 189 t) is lower than MSY (13 965 t), the annual effort of 6 920 tpd or 1 488 000 bd (F= 17.8 and E = 0.89) is far beyond f^,. Considering the fact that this prawn is also exploited by other gears with an annual average of 10 180 t during 1985-89, a conservative estimate of 25 000 t as potential stock for the whole country is made

Ultrasonography and color Doppler in juvenile idiopathic arthritis: diagnosis and follow-up of ultrasound-guided steroid injection in the wrist region. A descriptive interventional study

<p>Abstract</p> <p>Background</p> <p>The wrist region is one of the most complex joints of the human body. It is prone to deformity and functional impairment in juvenile idiopathic arthritis (JIA), and is difficult to examine clinically. The aim of this study was to evaluate the role of ultrasonography (US) with Doppler in diagnosis of synovitis, guidance of steroid injections, and follow-up examinations of the wrist in JIA.</p> <p>Methods</p> <p>In 11 patients (median age 12.5 years, range 2-16), 15 wrists with clinically active arthritis were assessed clinically by US and color Doppler (Logiq 9, GE, 16-4 MHz linear transducer) prior to and 1 and 4 weeks after US-guided steroid injection.</p> <p>Results</p> <p>US detected synovitis in the radio-carpal joints, the midcarpal joints, and the tendon sheaths in 87%, 53% and 33% of the wrists, respectively. Multiple compartments were involved in 67%. US-guidance allowed accurate placement of steroid in all 21 injected compartments, with a low rate of subcutaneous atrophy. Synovial hypertrophy was normalized in 86% of the wrists, hyperemia in 91%, and clinically active arthritis in 80%.</p> <p>Conclusions</p> <p>US enabled detection of synovial inflammation in compartments that are difficult to evaluate clinically and exact guidance of injections, and it was valuable for follow-up examinations. Normalization of synovitis was achieved in most cases, which supports the notion that US is an important tool in management of wrist involvement in JIA.</p

Microwave assisted solvent free synthesis of 1,3-diphenylpropenones

<p>Abstract</p> <p>Background</p> <p>1,3-Diphenylpropenones (chalcones) are well known for their diverse array of bioactivities. Hydroxyl group substituted chalcones are the main precursor in the synthesis of flavonoids. Till date various methods have been developed for the synthesis of these very interesting molecules. Continuing our efforts for the development of simple, eco-friendly and cost-effective methodologies, we report here a solvent free condensation of aryl ketones and aldehydes using iodine impregnated alumina under microwave activation. This new protocol has been applied to a variety of substituted aryl carbonyls with excellent yield of substituted 1,3-diphenylpropenones.</p> <p>Results</p> <p>Differently substituted chalcones were synthesized using iodine impregnated neutral alumina as catalyst in 79-95% yield in less than 2 minutes time under microwave activation without using any solvent. The reaction was studied under different catalytic conditions and it was found that molecular iodine supported over neutral alumina gives the best yield. The otherwise difficult single step condensation of hydroxy substituted aryl carbonyls is an attractive feature of this protocol to obtain polyhydroxychalcones in excellent yields. In order to find out the general applicability of this new endeavor it was successfully applied for the synthesis of 15 different chalcones including highly bioactive prenylated hydroxychalcone xanthohumol.</p> <p>Conclusion</p> <p>A new, simple and solvent free method was developed for the synthesis of substituted chalcones in environmentally benign way. The mild reaction conditions, easy work-up, clean reaction profiles render this approach as an interesting alternative to the existing methods.</p