Deformed shape invariance and exactly solvable Hamiltonians with position-dependent effective mass

Known shape-invariant potentials for the constant-mass Schrodinger equation are taken as effective potentials in a position-dependent effective mass (PDEM) one. The corresponding shape-invariance condition turns out to be deformed. Its solvability imposes the form of both the deformed superpotential and the PDEM. A lot of new exactly solvable potentials associated with a PDEM background are generated in this way. A novel and important condition restricting the existence of bound states whenever the PDEM vanishes at an end point of the interval is identified. In some cases, the bound-state spectrum results from a smooth deformation of that of the conventional shape-invariant potential used in the construction. In others, one observes a generation or suppression of bound states, depending on the mass-parameter values. The corresponding wavefunctions are given in terms of some deformed classical orthogonal polynomials.Comment: 26 pages, no figure, reduced secs. 4 and 5, final version to appear in JP

Dietary L-arginine supplementation reduces Methotrexate-induced intestinal mucosal injury in rat

<p>Abstract</p> <p>Background</p> <p>Arginine (ARG) and nitric oxide maintain the mucosal integrity of the intestine in various intestinal disorders. In the present study, we evaluated the effects of oral ARG supplementation on intestinal structural changes, enterocyte proliferation and apoptosis following methotrexate (MTX)-induced intestinal damage in a rat.</p> <p>Methods</p> <p>Male rats were divided into four experimental groups: Control rats, CONTR-ARG rats, were treated with oral ARG given in drinking water 72 hours before and 72 hours following vehicle injection, MTX rats were treated with a single dose of methotrexate, and MTX-ARG rats were treated with oral ARG following injection of MTX. Intestinal mucosal damage, mucosal structural changes, enterocyte proliferation and enterocyte apoptosis were determined 72 hours following MTX injection. RT-PCR was used to determine bax and bcl-2 mRNA expression.</p> <p>Results</p> <p>MTX-ARG rats demonstrated greater jejunal and ileal bowel weight, greater ileal mucosal weight, greater ileal mucosal DNA and protein levels, greater villus height in jejunum and ileum and crypt depth in ileum, compared to MTX animals. A significant decrease in enterocyte apoptosis in the ileum of MTX-ARG rats (vs MTX) was accompanied by decreased bax mRNA and protein expression and increased bcl-2 protein levels.</p> <p>Conclusions</p> <p>Treatment with oral ARG prevents mucosal injury and improves intestinal recovery following MTX- injury in the rat.</p

Emerging applications of nanoparticles for lung cancer diagnosis and therapy

Lung cancer is by far the leading cause of cancer-related mortality worldwide, most of them being active tobacco smokers. Non small cell lung cancer accounts for around 85% to 90% of deaths, whereas the rest is contributed by small cell lung cancer. The extreme lethality of lung cancer arises due to lack of suitable diagnostic procedures for early detection of lung cancer and ineffective conventional therapeutic strategies. In course with desperate attempts to address these issues independently, a multifunctional nanotherapeutic or diagnostic system is being sought as a favorable solution. The manifestation of physiochemical properties of such nanoscale systems is tuned favorably to come up with a versatile cancer cell targeted diagnostic and therapeutic system. Apart from this, the aspect of being at nanoscale by itself confers the system with an advantage of passive accumulation at the site of tumor. This review provides a broad perspective of three major subclasses of such nanoscale therapeutic and diagnostic systems which include polymeric nanoparticles-based approaches, metal nanoparticles-based approaches, and bio-nanoparticles-based approaches. This review work also serves the purpose of gaining an insight into the pros and cons of each of these approaches with a prospective improvement in lung cancer therapeutics and diagnostics

On the 3n+l Quantum Number in the Cluster Problem

It has recently been suggested that an exactly solvable problem characterized by a new quantum number may underlie the electronic shell structure observed in the mass spectra of medium-sized sodium clusters. We investigate whether the conjectured quantum number 3n+l bears a similarity to the quantum numbers n+l and 2n+l, which characterize the hydrogen problem and the isotropic harmonic oscillator in three dimensions.Comment: 8 pages, revtex, 4 eps figures included, to be published in Phys.Rev.A, additional material available at http://radix2.mpi-stuttgart.mpg.de/koch/Diss

Exact propagators for SUSY partners

Pairs of SUSY partner Hamiltonians are studied which are interrelated by usual (linear) or polynomial supersymmetry. Assuming the model of one of the Hamiltonians as exactly solvable with known propagator, expressions for propagators of partner models are derived. The corresponding general results are applied to "a particle in a box", the Harmonic oscillator and a free particle (i.e. to transparent potentials).Comment: 31 page

Eigenphase preserving two-channel SUSY transformations

We propose a new kind of supersymmetric (SUSY) transformation in the case of the two-channel scattering problem with equal thresholds, for partial waves of the same parity. This two-fold transformation is based on two imaginary factorization energies with opposite signs and with mutually conjugated factorization solutions. We call it an eigenphase preserving SUSY transformation as it relates two Hamiltonians, the scattering matrices of which have identical eigenphase shifts. In contrast to known phase-equivalent transformations, the mixing parameter is modified by the eigenphase preserving transformation.Comment: 16 pages, 1 figur

Causes and Correlates of Calf Mortality in Captive Asian Elephants (Elephas maximus)

Juvenile mortality is a key factor influencing population growth rate in density-independent, predation-free, well-managed captive populations. Currently at least a quarter of all Asian elephants live in captivity, but both the wild and captive populations are unsustainable with the present fertility and calf mortality rates. Despite the need for detailed data on calf mortality to manage effectively populations and to minimize the need for capture from the wild, very little is known of the causes and correlates of calf mortality in Asian elephants. Here we use the world's largest multigenerational demographic dataset on a semi-captive population of Asian elephants compiled from timber camps in Myanmar to investigate the survival of calves (n = 1020) to age five born to captive-born mothers (n = 391) between 1960 and 1999. Mortality risk varied significantly across different ages and was higher for males at any age. Maternal reproductive history was associated with large differences in both stillbirth and liveborn mortality risk: first-time mothers had a higher risk of calf loss as did mothers producing another calf soon (<3.7 years) after a previous birth, and when giving birth at older age. Stillbirth (4%) and pre-weaning mortality (25.6%) were considerably lower than those reported for zoo elephants and used in published population viability analyses. A large proportion of deaths were caused by accidents and lack of maternal milk/calf weakness which both might be partly preventable by supplementary feeding of mothers and calves and work reduction of high-risk mothers. Our results on Myanmar timber elephants with an extensive keeping system provide an important comparison to compromised survivorship reported in zoo elephants. They have implications for improving captive working elephant management systems in range countries and for refining population viability analyses with realistic parameter values in order to predict future population size of the Asian elephant

National trends in hospital-acquired preventable adverse events after major cancer surgery in the USA

Objectives: While multiple studies have demonstrated variations in the quality of cancer care in the USA, payers are increasingly assessing structure-level and process-level measures to promote quality improvement. Hospital-acquired adverse events are one such measure and we examine their national trends after major cancer surgery. Design: Retrospective, cross-sectional analysis of a weighted-national estimate from the Nationwide Inpatient Sample (NIS) undergoing major oncological procedures (colectomy, cystectomy, oesophagectomy, gastrectomy, hysterectomy, lung resection, pancreatectomy and prostatectomy). The Agency for Healthcare Research and Quality Patient Safety Indicators (PSIs) were utilised to identify trends in hospital-acquired adverse events. Setting: Secondary and tertiary care, US hospitals in NIS Participants: A weighted-national estimate of 2 508 917 patients (>18 years, 1999–2009) from NIS. Primary outcome measures Hospital-acquired adverse events. Results: 324 852 patients experienced ≥1-PSI event (12.9%). Patients with ≥1-PSI experienced higher rates of in-hospital mortality (OR 19.38, 95% CI 18.44 to 20.37), prolonged length of stay (OR 4.43, 95% CI 4.31 to 4.54) and excessive hospital-charges (OR 5.21, 95% CI 5.10 to 5.32). Patients treated at lower volume hospitals experienced both higher PSI events and failure-to-rescue rates. While a steady increase in the frequency of PSI events after major cancer surgery has occurred over the last 10 years (estimated annual % change (EAPC): 3.5%, p<0.001), a concomitant decrease in failure-to-rescue rates (EAPC −3.01%) and overall mortality (EAPC −2.30%) was noted (all p<0.001). Conclusions: Over the past decade, there has been a substantial increase in the national frequency of potentially avoidable adverse events after major cancer surgery, with a detrimental effect on numerous outcome-level measures. However, there was a concomitant reduction in failure-to-rescue rates and overall mortality rates. Policy changes to improve the increasing burden of specific adverse events, such as postoperative sepsis, pressure ulcers and respiratory failure, are required

A quantum point contact for neutral atoms

We show that the conductance of neutral atoms through a tightly confining waveguide constriction is quantized in units of lambda_dB^2/pi, where lambda_dB is the de Broglie wavelength of the incident atoms. Such a constriction forms the atom analogue of an electron quantum point contact and is an example of quantum transport of neutral atoms in an aperiodic system. We present a practical constriction geometry that can be realized using a microfabricated magnetic waveguide, and discuss how a pair of such constrictions can be used to study the quantum statistics of weakly interacting gases in small traps.Comment: 5 pages with 3 figures. To appear in Phys. Rev. Let

Home Range and Ranging Behaviour of Bornean Elephant (Elephas maximus borneensis) Females

BACKGROUND: Home range is defined as the extent and location of the area covered annually by a wild animal in its natural habitat. Studies of African and Indian elephants in landscapes of largely open habitats have indicated that the sizes of the home range are determined not only by the food supplies and seasonal changes, but also by numerous other factors including availability of water sources, habitat loss and the existence of man-made barriers. The home range size for the Bornean elephant had never been investigated before. METHODOLOGY/PRINCIPAL FINDINGS: The first satellite tracking program to investigate the movement of wild Bornean elephants in Sabah was initiated in 2005. Five adult female elephants were immobilized and neck collars were fitted with tracking devices. The sizes of their home range and movement patterns were determined using location data gathered from a satellite tracking system and analyzed by using the Minimum Convex Polygon and Harmonic Mean methods. Home range size was estimated to be 250 to 400 km(2) in a non-fragmented forest and 600 km(2) in a fragmented forest. The ranging behavior was influenced by the size of the natural forest habitat and the availability of permanent water sources. The movement pattern was influenced by human disturbance and the need to move from one feeding site to another. CONCLUSIONS/SIGNIFICANCE: Home range and movement rate were influenced by the degree of habitat fragmentation. Once habitat was cleared or converted, the availability of food plants and water sources were reduced, forcing the elephants to travel to adjacent forest areas. Therefore movement rate in fragmented forest was higher than in the non-fragmented forest. Finally, in fragmented habitat human and elephant conflict occurrences were likely to be higher, due to increased movement bringing elephants into contact more often with humans