Inscription of type I and depressed cladding waveguides in lithium niobate using a femtosecond laser.

We describe two types of waveguides (type I and depressed cladding) inscribed in lithium niobate using a variable repetition rate (200 kHz-25 MHz), 270 fs duration fiber laser. The type I modification-based waveguides have propagation losses in the range from 1.2 to 10 dB/cm at 1550 nm, depending on experimental parameters. These waveguides are not permanent; they deteriorate over time. Such deterioration of waveguides can be slowed down from 30 days to 100 days by pre-annealing the samples and by writing at a 720 kHz laser repetition rate. The propagation losses measured at 1550 nm show significant improvement for pre-annealed samples. The depressed cladding-inscribed waveguides are permanent, but the propagation loss depends on the number of damage tracks. A track separation of ∼1 µm between adjacent damage tracks yields the lowest propagation loss of 0.5 dB/cm at 1550 nm for a 40 µm diameter waveguide. We observe multimode guidance for sizes in the range of 20-80 µm in these waveguide structures at 1550 nm. Their crystalline nature is found to remain intact, as inferred from second-harmonic generation within the waveguide region.

Ultrafast dynamics of hemin aggregates.

The effects of solvents on the conformation of hemin and their implications on the dynamics of the complex have been studied using the time-resolved optical Kerr effect (OKE) with 35 fs laser pulses (at a central wavelength of 800 nm). The OKE enabled estimation to be made of the third-order nonlinear electronic susceptibility (χ(3)) of hemin solutions: it was found to be significantly smaller than that in hemin thin films. The real and imaginary components of χ(3) were negative in both the solvents, suggesting that one-photon as well as two-photon absorption processes contribute to the nonlinear electronic susceptibility of hemin. Our study of the ultrafast heme dynamics not only unveils the instantaneous electronic response related to electronic susceptibility but also brings to the fore a novel libration process that has hitherto remained undetected. The hindered rotation in the femtosecond domain that may be responsible for this libration process possibly stems from π-π hemin oligomers formed in aqueous solution. The present results provide new insights into the conformational dynamics in the self-assembly of heme oligomers that may also be significant in certain pathogenic conditions where free heme is formed in biological systems.

Umbilical artery histomorphometry: a link between the intrauterine environment and kidney development.

Prematurity is a risk factor for hypertension, vascular stiffness, nephron deficit and adult onset cardiorenal disease. The vascular tree and kidneys share morphogenic drivers that promote maturation in utero before 36 weeks of gestation. Vascular elastin accrual terminates after birth leaving collagen to promote vascular stiffness. Our objective was to determine if the histomorphometry of the umbilical artery, an extension of the aorta, parallels nephron mass across gestational age groups. From a cohort of 54 newborns, 32 umbilical cord specimens were adequate for evaluation. The umbilical cord was sectioned, stained with trichrome, and digitalized. Muscular and collagenous areas of the umbilical artery were measured in pixels using the Image J 1.48q software. Total kidney volume was measured by ultrasound and factored by body surface area (TKV/BSA). The umbilical artery total area was significantly greater in term v. preterm infants (9.3±1.3 v. 7.0±2.0 mm2; P<0.05) and increased with gestational age; while the percent muscular and collagen areas were independent of gestational age (R 2=0.04; P=ns). Percent muscular area correlated positively with TKV/BSA (r=0.53; P=0.002); while an increase in collagen correlated inversely with kidney mass (r=-0.53; P=0.002). In conclusion, an enhanced % muscular area and presumed vascular elasticity was associated with increased renal mass in all infants. Umbilical artery histomorphometry provides a link between the intrauterine environment, vascular and kidney development.

Femtosecond supercontinuum generation in water in the vicinity of absorption bands.

We show that it is possible to overcome the perceived limitations caused by absorption bands in water so as to generate supercontinuum (SC) spectra in the anomalous dispersion regime that extend well beyond 2000 nm wavelength. By choosing a pump wavelength within a few hundred nanometers above the zero-dispersion wavelength of 1048 nm, initial spectral broadening extends into the normal dispersion regime and, in turn, the SC process in the visible strongly benefits from phase-matching and matching group velocities between dispersive radiation and light in the anomalous dispersion regime. Some of the SC spectra are shown to encompass two and a half octaves.

Optical control of filamentation-induced damage to DNA by intense, ultrashort, near-infrared laser pulses.

We report on damage to DNA in an aqueous medium induced by ultrashort pulses of intense laser light of 800 nm wavelength. Focusing of such pulses, using lenses of various focal lengths, induces plasma formation within the aqueous medium. Such plasma can have a spatial extent that is far in excess of the Rayleigh range. In the case of water, the resulting ionization and dissociation gives rise to in situ generation of low-energy electrons and OH-radicals. Interactions of these with plasmid DNA produce nicks in the DNA backbone: single strand breaks (SSBs) are induced as are, at higher laser intensities, double strand breaks (DSBs). Under physiological conditions, the latter are not readily amenable to repair. Systematic quantification of SSBs and DSBs at different values of incident laser energy and under different external focusing conditions reveals that damage occurs in two distinct regimes. Numerical aperture is the experimental handle that delineates the two regimes, permitting simple optical control over the extent of DNA damage.

Optically trapping tumor cells to assess differentiation and prognosis of cancers.

We report an optical trapping method that may enable assessment of the differentiation status of cancerous cells by determining the minimum time required for cell-cell adhesion to occur. A single, live cell is trapped and brought into close proximity of another; the minimum contact time required for cell-cell adhesion to occur is measured using transformed cells from neural tumor cell lines: the human neuroblastoma SK-N-SH and rat C6 glioma cells. Earlier work on live adult rat hippocampal neural progenitors/stem cells had shown that a contact minimum of ~5 s was required for cells to adhere to each other. We now find the average minimum time for adhesion of cells from both tumor cell lines to substantially increase to ~20-25 s, in some cases up to 45 s. Upon in vitro differentiation of these cells with all-trans retinoic acid the average minimum time reverts to ~5-7 s. This proof-of-concept study indicates that optical trapping may be a quick, sensitive, and specific method for determining differentiation status and, thereby, the prognosis of cancer cells.

Indian psychiatric society multicentric study: Correlates of prescription patterns of psychotropics in India.

BACKGROUND: There is a lack of information on the clinical and sociodemographic correlates of prescription of psychotropics by psychiatrists. AIM AND OBJECTIVE: This study aimed to evaluate the relationship of prescription patterns with various clinical and sociodemographic variables. METHODOLOGY: Data of prescription patterns, psychiatric diagnosis, sociodemographic variables, and comorbid physical illnesses were collected for 4480 patients, across 11 centers. RESULTS: Females are more often prescribed escitalopram, sertraline, amitriptyline, amisulpride, nonlithium mood stabilizers, and benzodiazepines, whereas males are more often prescribed fluoxetine, olanzapine, two antipsychotics concurrently, typical antipsychotics, valproate, lithium, and more than one benzodiazepine. Elderly (>65 years) participants are more often prescribed sertraline when compared to adolescents. In addition, elderly more often receive quetiapine and less often are prescribed benzodiazepines. Those with comorbid neurological disorders are commonly prescribed antipsychotics, amitriptyline, and more than one antidepressant and are less commonly prescribed lithium, combination of two mood stabilizers, and benzodiazepines. Those with cardiac ailments are more commonly prescribed sertraline, quetiapine, and lithium and less frequently prescribed amitriptyline, fluoxetine, olanzapine, risperidone, and typical antipsychotics. Those with diabetes mellitus more often received escitalopram and quetiapine. Presence of more than one psychiatric diagnosis was associated with the use of more number of medications. Further, diagnosis of affective disorders was associated with the use of a higher number of medications. CONCLUSION: Findings of the present study suggest that sociodemographic variables and physical and psychiatric comorbidity influence the prescription patterns of psychotropics.

Influencing supercontinuum generation by phase distorting an ultrashort laser pulse.

We show that the spectral distribution of the supercontinuum (SC) generated in barium fluoride is amenable to alteration simply by controlling the second- and third-order phase distortion of incident femtosecond-duration pulses. The second- and third-order phase distortions are controlled by an acoustic-optic programmable dispersive filter (AOPDF). The spectral extent on the blue side of the SC is influenced by independently varying the phase distortion of an ultrashort laser pulse.

Selective breaking of bonds in water with intense, 2-cycle, infrared laser pulses.

One of the holy grails of contemporary science has been to establish the possibility of preferentially breaking one of several bonds in a molecule. For instance, the two O-H bonds in water are equivalent: given sufficient energy, either one of them is equally likely to break. We report bond-selective molecular fragmentation upon application of intense, 2-cycle pulses of 800 nm laser light: we demonstrate up to three-fold enhancement for preferential bond breaking in isotopically substituted water (HOD). Our experimental observations are rationalized by means of ab initio computations of the potential energy surfaces of HOD, HOD(+), and HOD(2+) and explorations of the dissociation limits resulting from either O-H or O-D bond rupture. The observations we report present a formidable theoretical challenge that need to be taken up in order to gain insights into molecular dynamics, strong field physics, chemical physics, non-adiabatic processes, mass spectrometry, and time-dependent quantum chemistry.

Indian Psychiatric Society multicentric study: Prescription patterns of psychotropics in India.

BACKGROUND: There is a lack of national level data from India on prescription of psychotropics by psychiatrists. AIM AND OBJECTIVE: This study aimed to assess the first prescription handed over to the psychiatrically ill patients whenever they contact a psychiatrist. MATERIALS AND METHODS: Data were collected across 11 centers. Psychiatric diagnosis was made as per the International Classification of Diseases Classification of Mental and Behavioural Disorders 10(th) edition criteria based on Mini International Neuropsychiatric Interview, and the data of psychotropic prescriptions was collected. RESULTS: Study included 4480 patients, slightly more than half of the subjects were of male (54.8%) and most of the participants were married (71.8%). Half of the participants were from the urban background, and about half (46.9%) were educated up to or beyond high school. The most common diagnostic category was that of affective disorders (54.3%), followed by Neurotic, stress-related and somatoform disorders (22.2%) and psychotic disorders (19.1%). Other diagnostic categories formed a very small proportion of the study participants. Among the antidepressants, most commonly prescribed antidepressant included escitalopram followed by sertraline. Escitalopram was the most common antidepressant across 7 out of 11 centers and second most common in three centers. Among the antipsychotics, the most commonly prescribed antipsychotic was olanzapine followed by risperidone. Olanzapine was the most commonly prescribed antipsychotic across 6 out of 11 centers and second most common antipsychotic across rest of the centers. Among the mood stabilizers valproate was prescribed more often, and it was the most commonly prescribed mood stabilizer in 8 out of 11 centers. Clonazepam was prescribed as anxiolytic about 5 times more commonly than lorazepam. Clonazepam was the most common benzodiazepine prescribed in 6 out of the 11 centers. Rate of polypharmacy was low. CONCLUSION: Escitalopram is the most commonly prescribed antidepressant, olanzapine is the most commonly prescribed antipsychotic and clonazepam is most commonly prescribed benzodiazepine. There are very few variations in prescription patterns across various centers.

DNA damage by OH radicals produced using intense, ultrashort, long wavelength laser pulses.

We probe femtosecond laser induced damage to aqueous DNA, relying on strong-field interaction with water wherein electrons and free radicals are generated in situ; these, in turn, interact with DNA plasmids under physiological conditions, producing nicks. Exposure to intense femtosecond pulses of 1350 and 2200 nm light induces single strand breaks and double strand breaks (DSBs) in DNA. At the longer wavelength (and at higher intensities), rotationally hot OH radicals induce DSBs, producing linear DNA. Strand breaks occur due to single or multiple OH hits on DNA. With 2200 nm light, DSBs are formed mostly by the action of two OH radicals; use of OH scavengers establishes that the probability of a two-hit event reduces much faster than a one-hit event as scavenger concentration is increased. Thermal effects do not induce DSBs with 2200 nm light.

Pituitary apoplexy with reversible cerebral vasoconstrictive syndrome after spinal anaesthesia for emergency caesarean section: an uncommon cause for postpartum headache.

Pituitary apoplexy is a rare condition involving pituitary necrosis following either pituitary haemorrhage or infarction. Similarly, reversible cerebral vasoconstrictive syndrome is a cerebrovascular disorder characterised by diffuse, multifocal narrowing of cerebral arteries. Both may present with an acute, intense headache and associated neurological deficits. In postpartum women, these conditions should be considered in the differential diagnosis of post-dural puncture headache following regional anaesthesia, as serious morbidity may ensue if they are left untreated. We report the case of a patient who developed pituitary apoplexy during an emergency caesarean section under spinal anaesthesia. It was further complicated by the development of reversible cerebral vasoconstriction syndrome and stroke.

Carrier-envelope-phase effects in ultrafast strong-field ionization dynamics of multielectron systems: Xe and CS2.

Carrier-envelope-phase- (CEP) stabilized 5 and 22 fs pulses of intense 800 nm light are used to probe the strong-field ionization dynamics of xenon and carbon disulfide. We compare ion yields obtained with and without CEP stabilization. With 8-cycle (22 fs) pulses, Xe(6+) yields are suppressed (relative to Xe(+)) by 30%-50%, depending on phase, reflecting the phase dependence of nonsequential ionization and its contribution to the formation of higher charge states. Ion yields for Xe(q+) (q = 2-4) with CEP-stabilized pulses are enhanced (by up to 50%) compared to those with CEP-unstabilized pulses. Such enhancement is particularly pronounced with 2-cycle (5 fs) pulses and is distinctly phase dependent. Orbital shape and symmetry affect how CS(2) responds to variations in optical field that are effected as CEP is altered, keeping intensity constant. Molecular fragmentation is found to depend on field strength (not intensity); the relative enhancement of fragmentation when CEP-stabilized 2-cycle pulses are used is found to be at the expense of molecular ionization.

Emotional intelligence, perceived stress and burnout among resident doctors: an assessment of the relationship.

BACKGROUND: Burnout is an increasing problem among the medical fraternity, especially resident doctors. We assessed the relationship between burnout, emotional intelligence and perceived stress in an attempt to explore a probable solution. METHODS: Residents in the departments of medicine (n=29) and surgery (n=27) were assessed with a specially designed proforma consisting of participant's profile sheet, Shirom-Melamed Burnout Measure (SMBM), Trait Emotional Intelligence Questionnaire and Perceived Stress Scale (PSS). Correlation and mediational analysis were used to analyse the data. RESULTS: The findings showed a positive correlation of burnout with perceived stress and a negative correlation with trait emotional intelligence (EI). Perceived stress also showed a negative correlation with trait EI. Mediation analysis showed that perceived stress mediates the effect of trait EI on burnout. CONCLUSION: Enhancing EI through training may be an important intervention for targeting burnout.

Legal awareness and responsibilities of nursing staff in administration of patient care in a trust hospital.

INTRODUCTION: The enactment of various legal provisions like Consumer Protection Act, Right to Information Act and standardization of procedures and practices have brought nursing care under legal ambit. Needless to say, the level of legal awareness amidst nursing staff in India is abysmally low. Present study was undertaken to assess the level of legal awareness and responsibilities of nursing staff in administration of patient care at a trust hospital. METHODS: An open ended questionnaire was prepared to assess the level of legal awareness among the nursing staff. The GNM and ANM nursing staff deployed at the nursing home and general wards only were randomly screened and specialty nurses were exempted. RESULTS: The knowledge on various legal provisions, as was applicable to nursing, across all categories of nurses which were under review, was found to be poor. The nursing staff had poor knowledge on patients' rights and also on their legal obligations towards patients. The GNM nurses fared better than ANM nurses. However, 46.67 % of nurses were found to be aware about cases of omission or commission. CONCLUSION: This study substantiated the fact that nurses had poor knowledge on the law that governed their profession and that in days to come, it would become increasingly difficult for them to avoid law suits which were prepared against them, unless remedial actions were taken.

Intense two-cycle laser pulses induce time-dependent bond hardening in a polyatomic molecule.

A time-dependent bond-hardening process is discovered in a polyatomic molecule (tetramethyl silane, TMS) using few-cycle pulses of intense 800 nm light. In conventional mass spectrometry, symmetrical molecules such as TMS do not exhibit a prominent molecular ion (TMS(+)) as unimolecular dissociation into [Si(CH(3))(3)](+) proceeds very fast. Under a strong field and few-cycle conditions, this dissociation channel is defeated by time-dependent bond hardening: a field-induced potential well is created in the TMS(+) potential energy curve that effectively traps a wave packet. The time dependence of this bond-hardening process is verified using longer-duration (≥100 fs) pulses; the relatively slower falloff of optical field in such pulses allows the initially trapped wave packet to leak out, thereby rendering TMS(+) unstable once again.

Optical trapping in an absorbing medium: from optical tweezing to thermal tweezing.

We report on optical trapping in a weakly absorbing medium, hemin, an iron-containing porphyrin that is an important component of hemoglobin. By altering the hemin concentration we are able to control the amount of optical energy that is absorbed; changing the hemin concentration from <12 mg/ml to >45 mg/ml enables the onset of thermal trapping to be observed. By estimating the trap strength using two different methods we are readily able to differentiate between the optical trapping and thermal trapping regimes. We also deduce the rise in temperature that occurs within the laser focal volume: temperature changes of 5-24 K are observed for laser power values of 10-90 mW for hemin concentrations of 0-50 mg/ml.

Adipokines and body fat composition in South Asians: results of the Metabolic Syndrome and Atherosclerosis in South Asians Living in America (MASALA) study.

OBJECTIVE: To investigate whether leptin and adiponectin are associated with body fat composition in a South Asian population independent of metabolic variables. DESIGN: Cross-sectional study. SUBJECTS: 150 South Asian men and women, between the ages of 45-79 years, in the San Francisco Bay Area without pre-existing clinical cardiovascular disease. MEASUREMENTS: Blood samples were obtained to measure glucose metabolism variables, lipid profiles and adipokines. Total body fat was determined using dual-energy X-ray absorptiometry. Abdominal computed tomography was used to measure subcutaneous, visceral and hepatic fat. RESULTS: Average body mass index (BMI) was overweight at 26.1±4.6 kg m(-2) and did not differ by sex. However, women had significantly more total body fat (P<0.001) and subcutaneous fat (P<0.001) than men, whereas men had significantly more visceral fat (P<0.001) and hepatic fat (P=0.04) than women. Women had significantly higher levels of adiponectin (P<0.01) and leptin (P<0.01). In sex-stratified analyses, leptin was strongly associated with all-body composition measures in women (P<0.05) as well as in men (P<0.05 except for hepatic fat), whereas there was an insignificant trend towards an inverse association between adiponectin and body composition in both women and men, which was significant in combined bivariate analyses. In multivariate analyses, leptin was strongly associated with all measures of adiposity, including BMI (P<0.001), total body fat (P<0.001), visceral fat (P<0.001) and hepatic fat (P=0.01). However, adiponectin's inverse association with adiposity was significantly attenuated by high-density lipoprotein (HDL), triglycerides and insulin resistance. The association between adipokines and diabetes was markedly attenuated after adjusting for body composition. CONCLUSION: Despite only modestly elevated BMI, South Asians have elevated levels of total and regional adiposity. Leptin is strongly associated with adiposity, whereas adiponectin's association with adiposity is attenuated by metabolic variables in South Asians. Adipokines in association with adiposity have an important role in the development of diabetes.

Effect of intense, ultrashort laser pulses on DNA plasmids in their native state: strand breakages induced by in situ electrons and radicals.

Single strand breaks are induced in DNA plasmids, pBR322 and pUC19, in aqueous media exposed to strong fields generated using ultrashort laser pulses (820 nm wavelength, 45 fs pulse duration, 1 kHz repetition rate) at intensities of 1-12 TW cm(-2). The strong fields generate, in situ, electrons and radicals that induce transformation of supercoiled DNA into relaxed DNA, the extent of which is quantified. Introduction of electron and radical scavengers inhibits DNA damage; results indicate that OH radicals are the primary (but not sole) cause of DNA damage.

Communication: Ionization and Coulomb explosion of xenon clusters by intense, few-cycle laser pulses.

Intense, ultrashort pulses of 800 nm laser light (12 fs, approximately 4 optical cycles) of peak intensity 5x10(14) W cm(-2) have been used to irradiate gas-phase Xe(n) clusters (n=500-25,000) so as to induce multiple ionization and subsequent Coulomb explosion. Energy distributions of exploding ions are measured in the few-cycle domain that does not allow sufficient time for the cluster to undergo expansion due to Coulombic and hydrodynamic pressures. This results in overall dynamics that appear to be significantly different to those in the many-cycle regime. One manifestation is that the maximum ion energies are measured to be much lower than those obtained when longer pulses of the same intensity are used. Ion yields are cluster-size independent but polarization dependent in that they are significantly larger when the polarization is perpendicular to the detection axis than along it. This unexpected behavior is qualitatively rationalized in terms of a spatially anisotropic shielding effect induced by the electronic charge cloud within the cluster.