Did a stellar fly-by shape the planetary system around Pr 0211 in the cluster M 44?

Out of the $\sim$ 3000 exoplanets detected so far, only fourteen planets are members of open clusters: among them an exoplanet system around Pr 0211 in the cluster M44 which consists of at least two planets with the outer planet moving on a highly eccentric orbit at 5.5 AU. One hypothesis is that a close fly-by of a neighbouring star was responsible for the eccentric orbit. We test this hypothesis. First we determine the type of fly-by that would lead to the observed parameters and then use this result to determine the history of such fly-bys in simulations of the early dynamics in an M44-like environment. We find that although very close fly-bys are required to obtain the observed properties of Pr 0211c, such fly-bys are relatively common due to the high stellar density and longevity of the cluster. Such close fly-bys are most frequent during the first 1-2 Myr after cluster formation, corresponding to a cluster age $\leq$ 3 Myr. During the first 2 to 3 Myr about 6.5% of stars actually experience a fly-by that would lead to such a small system-size as observed for Pr0211 or even smaller. It is unclear whether planets generally form on such short timescales. However, afterwards the close fly-by rate is still 0.2-0.5 Myr$^{-1}$, which means extrapolating this to the age of M44 12%-20% of stars would experience such close fly-bys over this timespan. Our simulations show that the fly-by scenario is a realistic option for the formation of eccentricity orbits of the planets in M44. The occurrence of such events is relatively high leading to the expectation that similar systems are likely common in open clusters in general.Comment: 7 pages, 6 figures, accepted by A&

Effects of inclined star-disk encounter on protoplanetary disk size

Most, if not all, young stars are initially surrounded by protoplanetary disks. Owing to the preferential formation of stars in stellar clusters, the protoplanetary disks around these stars may potentially be affected by the cluster environment. Various works have investigated the influence of stellar fly-bys on disks, although many of them consider only the effects due to parabolic, coplanar encounters often for equal-mass stars, which is only a very special case. We perform numerical simulations to study the fate of protoplanetary disks after the impact of parabolic star-disk encounter for the less investigated case of inclined up to coplanar, retrograde encounters, which is a much more common case. Here, we concentrate on the disk size after such encounters because this limits the size of the potentially forming planetary systems. In addition, with the possibilities that ALMA offers, now a direct comparison to observations is possible. Covering a wide range of periastron distances and mass ratios between the mass of the perturber and central star, we find that despite the prograde, coplanar encounters having the strongest effect on the disk size, inclined and even the least destructive retrograde encounters mostly also have a considerable effect, especially for close periastron passages. Interestingly, we find a nearly linear dependence of the disk size on the orbital inclination for the prograde encounters, but not for the retrograde case. We also determine the final orbital parameters of the particles in the disk such as eccentricities, inclinations, and semi-major axes. Using this information the presented study can be used to describe the fate of disks and also that of planetary systems after inclined encounters.Comment: 15 pages, 11 figures. Accepted for publication by Astronomy & Astrophysic

Outer solar system possibly shaped by a stellar fly-by

The planets of our solar system formed from a gas-dust disk. However, there are some properties of the solar system that are peculiar in this context. First, the cumulative mass of all objects beyond Neptune (TNOs) is only a fraction of what one would expect. Second, unlike the planets themselves, the TNOs do not orbit on coplanar, circular orbits around the Sun, but move mostly on inclined, eccentric orbits and are distributed in a complex way. This implies that some process restructured the outer solar system after its formation. However, some of TNOs, referred to as Sednoids, move outside the zone of influence of the planets. Thus external forces must have played an important part in the restructuring of the outer solar system. The study presented here shows that a close fly-by of a neighbouring star can simultaneously lead to the observed lower mass density outside 30 AU and excite the TNOs onto eccentric, inclined orbits, including the family of Sednoids. In the past it was estimated that such close fly-bys are rare during the relevant development stage. However, our numerical simulations show that such a scenario is much more likely than previously anticipated. A fly-by also naturally explains the puzzling fact that Neptune has a higher mass than Uranus. Our simulations suggest that many additional Sednoids at high inclinations still await discovery, perhaps including bodies like the postulated planet X.Comment: 16 pages, 7 figures, accepted by Ap

Numerical simulations of star and disc formation

Magnetized, cold, dense molecular cloud cores provide the birth environment for stars, discs, and planets. The multi-scale scenario of low-mass star formation occurs via the formation of two quasi-hydrostatic cores. Furthermore, the conservation of angular momentum can lead to the formation of a disc around the second core (i.e.~the forming protostar). During these early stages of star formation, magnetically driven outflows and jets can be launched from the first and second cores, respectively. Star, disc, and outflow formation involve complex physical processes, which require a robust, self-consistent numerical treatment. In this thesis, we use numerical simulations to probe the gravitational collapse scenario that involves the transition of an isolated molecular cloud core to a hydrostatic core with a surrounding disc. We use the \emph{PLUTO} code to perform radiation (magneto-)hydrodynamic (MHD) collapse simulations, using one- and two-dimensional (2D) grids. We include the effects of self-gravity and a grey flux-limited diffusion approximation for the radiative transfer. Additionally, we use for the gas equation of state density- and temperature-dependent thermodynamic quantities to account for the dissociation, ionisation, and molecular vibrations and rotations. Our spherically symmetric simulations span seven orders of magnitude in spatial scale. We survey a wide range of initial low- to high-mass (0.5 -- 100~$M_{\odot}$) molecular cloud cores, yielding the largest parameter scan so far. Our results highlight the dependence of the first and second hydrostatic core properties on the initial cloud core properties. These simulations indicate that in the high-mass regime, the first hydrostatic cores do not have enough time to form due to large accretion rates. We further expand our studies to three different sets of 2D simulations using axial and midplane symmetry. First, we perform 2D simulations for non-rotating molecular cloud cores with masses of 1~$M_{\odot}$, 5~$M_{\odot}$, 10~$M_{\odot}$, and 20~$M_{\odot}$. For each of these cases, we use an unprecedented resolution to model the evolution of the second core for $\geq$~100 years after its formation. For the first time, we demonstrate that convection is generated in the outer layers of the second core. This supports the intriguing possibility that dynamo-driven magnetic fields may be generated during the earliest phases of star formation. Following which, for the 1~$M_{\odot}$ case, we analyse the effects of solid-body rotation on the properties of the hydrostatic cores and disc formation. In this model, the first hydrostatic core evolves into a more oblate, pseudo-disc like structure and a sub-au disc starts forming after the formation of the second core. Finally, we explore the effects of ideal and non-ideal (including Ohmic resistivity) MHD during the collapse of rotating molecular cloud cores. We investigate the dependence of molecular outflows and disc formation on the initial cloud core mass, rotation, resistivity, and magnetic field strength. We find the presence of magnetically driven outflows launched from both first and second cores in the resistive models. We also reveal ongoing disc formation in some of our resistive simulations. In conclusion, we use detailed thermodynamical modelling to quantify the properties of the hydrostatic cores, outflows, and discs for collapse scenarios with a wide range of initial cloud core properties. The models presented herein will serve as the foundation for follow-up studies that link these theoretical insights with observational signatures

USE OF TECHNOLOGY IN E-COMMERCE BUSINESSES WITH SPECIAL REFERENCE TO SERVICE SECTORS

The use of electronic commerce by business in developed countries as well as developing countries has grown considerably in the past few years. E- commerce businesses are capturing the worldwide markets very easily and helping in earning profits. The use of E-commerce in service sectors is contributing in national income of the country and also generating employment opportunities in India. There are various Indian service sectors has done tremendous recognition not only in Indian markets but also world markets. The India’s telecom sector is growing and became popular in world market in providing better services to overseas buyers. E-commerce use in service sector enables the marketers to reach all areas of the world with minimal cost. It is very important to know about the challenges and opportunities in service sector using of e-commerce in India. The above study has taken for the study by the researcher

OPTIMIZATION OF EXTRACTION PARAMETERS FOR TOTAL FLAVONOIDS FROM GARDENIA GUMMIFERA GUM RESIN BY RESPONSE SURFACE METHODOLOGY

Objective: To optimize the extraction parameters for determining the highest yield of Total Flavonoids from Gardenia gummifera gum resin.Methods: In the present study, response surface methodology (RSM) with three level Box Behenken design (BBD) was performed to optimize extraction parameters for total flavonoids. Solvent concentration(A), extraction time (B) and extraction temperature(C) were considered for single factor experiment.Results: The highest flavonoid concentration was obtained with acetone 45.00% v/v, time 101.46 min, temperature 41.57 °C. The average experimental TFC under optimal conditions was 161.14 mg/g which was in close agreement with the predicted value of 163.42 mg/g.Conclusion: RSM-BBD is successfully applied in optimizing extraction conditions for extraction of total flavonoids from G. gummifera gum resin

Drug utilization study in dengue infection in a tertiary care hospital

Background: Dengue fever (DF) is a serious public health problem, gaining global attention because of its morbidity and mortality. Less studies on Drug utilization pattern of DF in India. The present study was undertaken to analyze Drug utilization pattern of dengue infection in a tertiary care hospital.Methods: A prospective cross-sectional study was conducted for a period of 2 months in a tertiary care hospital and the data was analyzed by using various drug use indicators.Results: A total of 52 prescriptions were analyzed. Male and female were (46.16%, 53.84%), A total of 330 drugs were prescribed. 86 (26.06%) antibiotics, 70 (21.21%) antipyretics, 51 (15.46%) antacids, 19 (5.76%) multivitamins, 52 (15.76%) anti-emetics and 52 (15.76%) papaya leaf extract was prescribed. 84 (25.46%) oral and 246 (74.54%) injectable drugs. IV-fluids given to all patients. 10 (19.24%) were given blood transfusion. 6.17 drugs per prescription. 96% drugs were prescribed by brand names. High DDD for drugs like diclofenac (184), doxycycline (115), metronidazole (2.5), pantoprazole (161.5), rabeprazole (34.6), ondansetron (200) was observed.Conclusions: Most commonly used drugs are antipyretics, antibiotics, antacids, antiemetic, papaya leaf extract. As the incidence of DF is increasing with epidemics, demand for specific treatment guidelines is in great need. Early recognition of the disease, with a rational approach in case management leads good clinical outcome

A study on knowledge and practices of over the counter medications among 1st year medical students

Background: Self-medication is widely practiced worldwide and often considered as a component of self-care. Selfmedication assumes a special significance among the medical students as they are the future medical practitioners and have a potential role in counselling the patients about the advantages and disadvantages of self-medication. Self-medication assumes a special significance among the medical students as they are the future medical practitioners. Medical students also differ from the general population because they are well-exposed to the knowledge about diseases and drugs. Therefore the present study was taken up to assess the extent of knowledge and practices of over the counter (OTC) drugs among the first year medical students in a tertiary care teaching hospital.Methods: A descriptive, cross sectional, non-interventional, observational study was conducted from November 2017 to January 2018 among 246 first year medical students. The data analyzed using descriptive statistics with percentages and averages using Statistical Package for Social Science (SPSS).Results: In the present study, it was found that 86% students practiced self-medication. Most common conditions for taking self-medication with OTC was fever (89%) followed by cough and cold (75%). 15% of them experienced adverse reactions on OTC self-medicated drugs. The main source of information during self-medication was reading material (56.3%) followed by advice from seniors/pharmacist (43.7%).Conclusions: Self-medication is widely practiced among undergraduate medical students. In this situation, we should educate the students about advantages and disadvantages of self-medication of over the counter drugs

A study of customer centric culture in realty sector (residential) in Pune.

This paper examines the importance of customer centric culture as a strategic approach to doing business in the 21st century hypercompetitive marketplace and market space. This paper focuses on the study the scenario of the residential /ownership flats in realty sector in India within Pune city through this paper researcher identifies the various growth phases and highlights the housing shortage. Based on the analysis of top Indian cities for their growth potential in future residential capital values, it identifies Pune which will yield the maximum growth. After profiling the city, key facts which contribute to its housing growth are studied in detail. The Pune housing market is divided into segments & each market segment is analyzed. A analysis is done to identify the shift of organizations from product centric to customer centric approach. The study ends with identifying the emerging Pune housing trends which indicate that the quality of life that its citizens will experience in future will match the global standards. The Indian real estate sector has been a major beneficiary of the strong economic growth witnessed in India Since the year 2000. The growth in the sector, supported by series of reforms, has not only resulted in significant residential and commercial realty sector, but also complemented the development of physical and social infrastructure of the country