1,352 research outputs found
Transition region of TEC enhancement phenomena during geomagnetically disturbed periods at mid-latitudes
Large-scale TEC perturbations/enhancements observed during the day sectors of major storm periods, 12-13&nbsp;February 2000, 23&nbsp;September 1999, 29&nbsp;October 2003, and 21&nbsp;November 2003, were studied using a high resolution GPS network over Japan. TEC enhancements described in the present study have large magnitudes (&ge;25&times;10<sup>16</sup> electrons/m<sup>2</sup>) compared to the quiet-time values and long periods (&ge;120 min). The sequential manner of development and the propagation of these perturbations show that they are initiated at the northern region and propagate towards the southern region of Japan, with velocities &gt;350 m/s. On 12&nbsp;February 2000, remarkably high values of TEC and background content are observed at the southern region, compared to the north, because of the poleward expansion of the equatorial anomaly crest, which is characterized by strong latitudinal gradients near 35&deg; N (26&deg; N geomagnetically). When the TEC enhancements, initiating at the north, propagate through the region 39-34&deg; N (30-25&deg; N geomagnetically), they undergo transitions characterized by a severe decrease in amplitude of TEC enhancements. This may be due to their interaction with the higher background content of the expanded anomaly crest. However, at the low-latitude region, below 34&deg; N, an increase in TEC is manifested as an enhanced ionization pattern (EIP). This could be due to the prompt penetration of the eastward electric field, which is evident from high values of the southward Interplanetary Magnetic Field component (IMF <i>B<sub>z</sub></i>) and AE index. The TEC perturbations observed on the other storm days also exhibit similar transitions, characterized by a decreasing magnitude of the perturbation component, at the region around 39-34&deg; N. In addition to this, on the other storm days, at the low-latitude region, below 34&deg; N, an increase in TEC (EIP feature) also indicates the repeatability of the above scenario. It is found that, the latitude and time at which the decrease in magnitude of the perturbation component/amplitude of the TEC enhancement are matching with the latitude and time of the appearance of the high background content. In the present study, on 12&nbsp;February 2000, the F-layer height increases at Wakkanai and Kokubunji, by exhibiting a typical dispersion feature of LSTID, or passage of an equatorward surge, which is matching with the time of occurrence of the propagating TEC perturbation component. Similarly, on 29&nbsp;October 2003, the increase in F-layer heights by more than 150km at Wakkanai and 90 km at Kokubunji around 18:00&nbsp;JST, indicates the role of the equatorward neutral wind. On that day, TEC perturbation observed at the northern region, after 18:30&nbsp;JST, which propagates towards south, could be caused mainly by the equatorward neutral wind, leading to an F-layer height increase. These observations imply the role of the equatorward neutral wind, which increases the F-layer height, by lifting the ionization to the regions of lower loss during daytime, when production is still taking place, which, in turn, increases the TEC values. <P style="line-height: 20px;"> Large-scale traveling ionospheric disturbances (LSTIDs) are considered as ionospheric manifestations of the passage of Atmospheric Gravity Waves (AGWs) that are generated at the high latitude by energy input from the magnetosphere to the low-latitude ionosphere. This study shows that large-scale TEC perturbations observed here are produced at the northern region due to the combined effects of the equatorward neutral wind, the subsequent F-layer height increase, and LSTIDs. When these perturbation components propagate through the region, 39-34&deg; N, they undergo transitions characterised by a decrease in magnitude. Also, at the low-latitude region, below 34&deg; N, an increase in the TEC exhibits EIP feature, due to the prompt penetration of the eastward electric field
Initial wave packets and the various power-law decreases of scattered wave packets at long times
The long time behavior of scattered wave packets from a
finite-range potential is investigated, by assuming to be
initially located outside the potential. It is then shown that can
asymptotically decrease in the various power laws at long time, according to
its initial characteristics at small momentum. As an application, we consider
the square-barrier potential system and demonstrate that exhibits
the asymptotic behavior , while another behavior like can
also appear for another .Comment: 5 pages, 1 figur
Free initial wave packets and the long-time behavior of the survival and nonescape probabilities
The behavior of both the survival S(t) and nonescape P(t) probabilities at
long times for the one-dimensional free particle system is shown to be closely
connected to that of the initial wave packet at small momentum. We prove that
both S(t) and P(t) asymptotically exhibit the same power-law decrease at long
times, when the initial wave packet in momentum representation behaves as O(1)
or O(k) at small momentum. On the other hand, if the integer m becomes greater
than 1, S(t) and P(t) decrease in different power-laws at long times.Comment: 4 pages, 3 figures, Title and organization changed, however the
results not changed, To appear in Phys. Rev.
Development of a high resolution land surface dataset for the South Asian monsoon region
In this study, we report the development of a high
resolution land surface dataset for the South Asian
monsoon region for studies on land surface processes,
and land and atmosphere coupling. The high resolu-
tion land data assimilation system was used to develop
the land surface dataset utilizing TRMM rainfall and
ECMWF atmospheric variables as forcing parameters. The dataset was developed at a spatial resolution of 0.5° and temporal resolution of 1 h and spans a period of 6 years, i.e. 1 January 2005 to 31 December 2010. The major highlights in the development of the present dataset are higher spatial and temporal resolution of land surface parameters, use of sub-daily forcing parameters including rainfall, use of MODIS land-use data in lieu of USGS land-use data and weekly varying vegetation fraction instead of monthly vegetation climatology. A comparison of soil moisture and soil temperature with limited surface observations of the IMD suggests reasonable reliability of the land surface data. The model sensible heat flux data are compared with in situ measurements at Ranchi and MEERA reanalysis data. The sensitivity analysis shows that the land surface data are sensitive to rainfall and green vegetation cover data used as the forcing parameters. The dataset has been used to discuss the variations of land surface processes associated with active and break spells and a severe heat wave observed in 2009. The present dataset will be useful for many applications, including initializing numerical models for weather prediction. This high resolution land surface dataset is available for research on request
Spiny Lobsters and Potential of Sea Cage Culture Spiny Lobster Resources in India
Fishery science and technology contributes a vital role in the augmentation of fish
production globally.Among the seafood items, spiny lobsters have a prime position in
terms of high unit value, demand, nutritional qualities with less perishable nature.
Lobsters have great demand in international and domestic market, especially from
tourism based beach resorts and restaurants as a luxury food. The annual lobster
landings in India has been declining from a peak of 4,075 t in 1985 to the present
annual average of 1,546 t. On an average, the fishery is contributed by Gujarat
(43.7%), Maharashtra (25.4%), Tamil Nadu(14.6%) and Kerala (13%) (CMFRI
Annual Report 2000-2015). Lobster fishing in India is mostly carried out by region
specific traditional fishermen communities inhabiting along the coastal belts of
different maritime states. Over the years the lobster fishery in India witnessed changes
in fishing pattern, utility pattern with the introduction of live export market , sea cage
culture and increased consumption and demand from tourism sector .
Live Lobsters have a prominent place in the sea food export market both in terms of
demand and price from Japan, Korea, China, Taiwan, Europe and USA. India
witnessed a sea change in foreign exchange earnings through marine products export
worth 46,975 million rupees during 1997-98 and 55,111.12 million rupees during
2014-15, from an initial value of 25 million rupees in 1950-51 (Sakthivel, 1999). The
marine products export accounted
and contributed 3.5 % of the total exports in 1990s. Our marine product exports in the
initial stages were in dried and canned form. It has gradually progressed into frozen
h 340 million
rupees in 1996-97 (Sakthivel, 1999). Spiny lobsters formed one of the items in the live
fish export along with mud crabs and reef fishes. The annual average revenue earnings
by India through the export of lobsters is amounted to Rs.74 crores
PDB134 Effect of Patient-Education on Health-Related Quality of Life of Diabetic Foot Ulcer Patients In A Tertiarycare Hospital
Antidiabetic activity of 3-hydroxyflavone analogues in high fructose fed insulin resistant rats
Synthetic 3-hydroxyflavone analogues (JY-1, JY-2, JY-3, JY-4), were tested for antidiabetic activity in high-fructose-diet-fed (66 %, for 6 weeks) insulin-resistant Wistar rats (FD-fed rats). The fasting blood glucose, insulin, creatinine and AGEs were decreased to near normal upon treatment with test compounds. Insulin resistance markers such as HOMA-IR, K-ITT, plasma triglycerides, lipids, endogenous antioxidant defense and glycogen were restored in FD-fed rats after treatment with 3-hydroxyflavones. It is known that insulin resistance is partly because of oxidative stress and hence antioxidant activity was determined. They exhibited significant in vitro DPPH and ABTS radical scavenging activity (IC50: 10.66-66.63 μM). Test
compounds inhibited ROS and NO production in RAW 264.7 cells (IC50: 10.39–42.63 μM) and they were found as potent as quercetin. Further, the test compounds inhibited lipid peroxidation at low concentrations (IC50: 99.61-217.47 μM). All test compounds at concentrations 100-200 μM protected calf thymus DNA-damage by Fenton reaction. In addition, test compounds inhibited protein glycation in different in vitro
antiglycation assays. JY-2 showed maximum potency in all the stages of glycation which was comparable to the standard quercetin and aminoguanidine. Test compounds also enhanced the glucose uptake by L6 myotubes at an EC50 much lower than that of quercetin. Thus the synthetic 3-hydroxyflavones were found to have good antidiabetic activity by pleotropic and multimodal suppression of insulin resistance and enhancement of glucose uptake by skeletal muscles. These compounds are non-toxic at the doses tested. Further, the combined antioxidant and antiglycation activities of these molecules have complementary benefits in management of diabetes
The various power decays of the survival probability at long times for free quantum particle
The long time behaviour of the survival probability of initial state and its
dependence on the initial states are considered, for the one dimensional free
quantum particle. We derive the asymptotic expansion of the time evolution
operator at long times, in terms of the integral operators. This enables us to
obtain the asymptotic formula for the survival probability of the initial state
, which is assumed to decrease sufficiently rapidly at large .
We then show that the behaviour of the survival probability at long times is
determined by that of the initial state at zero momentum . Indeed,
it is proved that the survival probability can exhibit the various power-decays
like for an arbitrary non-negative integers as ,
corresponding to the initial states with the condition as .Comment: 15 pages, to appear in J. Phys.
Analytic results for Gaussian wave packets in four model systems: II. Autocorrelation functions
The autocorrelation function, A(t), measures the overlap (in Hilbert space)
of a time-dependent quantum mechanical wave function, psi(x,t), with its
initial value, psi(x,0). It finds extensive use in the theoretical analysis and
experimental measurement of such phenomena as quantum wave packet revivals. We
evaluate explicit expressions for the autocorrelation function for
time-dependent Gaussian solutions of the Schrodinger equation corresponding to
the cases of a free particle, a particle undergoing uniform acceleration, a
particle in a harmonic oscillator potential, and a system corresponding to an
unstable equilibrium (the so-called `inverted' oscillator.) We emphasize the
importance of momentum-space methods where such calculations are often more
straightforwardly realized, as well as stressing their role in providing
complementary information to results obtained using position-space
wavefunctions.Comment: 18 pages, RevTeX, to appear in Found. Phys. Lett, Vol. 17, Dec. 200
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