970 research outputs found
Analysis of interaction between Arbuscular Mycorrhizal fungi and their Helper bacteria by MILPA model
Many recent researches carried out the research in mycorrhizal symbiosis to improve crop growth in the agriculture but they differ in their approaches like crops and the agricultural perspectives. The study focused on the interaction of Arbuscular mycorrhizal (AM) fungi and helper bacteria, influence maize growth through milpa as a model system to analyze soil enzyme activity of acid, alkaline phosphatase and signaling molecule of phospholipids fatty acid (PLFA) profile. Bioinoculants plays an important role in plant growth like nutrient mobilization, biocontrol and prevent the plants from stress. The maize crops were treated with bio inoculants such as Azospirillum, Azotobacter, Rhizobium,Pseudomonas and AM fungi. Significant diverse effects were observed with bioinoculants in the crops compared to control crop. The number spores formed was proportional to the rate of colonization.AM fungi association in plant roots helps the plants in nutrient uptake especially phosphorus (P) from soil materials. The enzyme activities were also found to influence the growth of the plant and phospholipids fatty acid (PLFA) profile influences the interaction between bacterium and AMF. Plant and phospholipids fatty acid analysis is asensitive and accurate method in determining microbial community structures, because it depends on living cell contents of microorganisms under in situ conditions. It confirmed with gas chromatographic analysis of PLFA to determination of the structure and total biomass of microbial community in treated soil samples
Surface melt and ponding on Larsen C Ice Shelf and the impact of föhn winds
A common precursor to ice shelf disintegration, most notably that of Larsen B Ice Shelf, is
unusually intense or prolonged surface melt and the presence of surface standing water. However, there
has been little research into detailed patterns of melt on ice shelves or the nature of summer melt ponds.
We investigated surface melt on Larsen C Ice Shelf at high resolution using Envisat advanced synthetic
aperture radar (ASAR) data and explored melt ponds in a range of satellite images. The improved
spatial resolution of SAR over alternative approaches revealed anomalously long melt duration in
western inlets. Meteorological modelling explained this pattern by föhn winds which were common in
this region.Melt ponds are difficult to detect using optical imagery because cloud-free conditions are rare
in this region and ponds quickly freeze over, but can be monitored using SAR in all weather conditions.
Melt ponds up to tens of kilometres in length were common in Cabinet Inlet, where melt duration was
most prolonged. The pattern of melt explains the previously observed distribution of ice shelf
densification, which in parts had reached levels that preceded the collapse of Larsen B Ice Shelf,
suggesting a potential role for föhn winds in promoting unstable conditions on ice shelves
Towards a census of the Galactic anticentre star clusters: colour-magnitude diagram and structural analyses of a sample of 50 objects
In this work we investigate the nature of 50 overdensities from the catalogue
of Froebrich, Scholz, and Raftery (FSR) projected towards the Galactic
anticentre, in the sector 160{\deg} \leq \ell \leq 200{\deg}. The sample
contains candidates with |b| \leq 20{\deg} classified by FSR as probable open
cluster (OC) and labelled with quality flags 2 and 3. Our main purpose is to
determine the nature of these OC candidates and the fraction of these objects
that are unknown OCs, as well as to derive astrophysical parameters (age,
reddening, distance, core and cluster radii) for the clusters and to
investigate the relationship among parameters. The analysis is based on 2MASS
J, (J-H), and (J-Ks) colour-magnitude diagrams (CMDs), and stellar radial
density profiles (RDPs) built with decontamination tools. The tools are a field
star decontamination algorithm, used to uncover the cluster's intrinsic CMD
morphology, and colour-magnitude filters to isolate stars with a high
probability of being cluster members. Out of the 50 objects, 16 (32%) are star
clusters. We show that 9 (18%) overdensities are new OCs (FSR 735, FSR 807, FSR
812, FSR 826, FSR 852, FSR 904, FSR 941, FSR 953, and FSR 955) and 7 (14%) are
previously studied or catalogued OCs (KKC1, FSR 795, Cz 22, FSR 828, FSR 856,
Cz 24, and NGC 2234). These are OCs with ages in the range 5 Myr to 1 Gyr, at
distances from the Sun 1.28 \precnapprox d_Sun(kpc) \precnapprox 5.78 and
Galactocentric distances 8.5 R_GC(kpc) \precnapprox 12.9. We also derive
parameters for the previously analysed OCs Cz 22 and NGC 2234. Five (10%)
candidates are classified as uncertain cases, and the remaining objects are
probable field fluctuations.Comment: 14 pages, 15 figure
The old Galactic open clusters FSR1716 and Czernik23
Open clusters older than Gyr are rare in the Galaxy. Affected by a
series of mass-decreasing processes, the stellar content of most open clusters
dissolves into the field in a time-scale shorter than Gyr. In this
sense, improving the statistics of old objects may provide constraints for a
better understanding of the dynamical dissolution of open clusters. Isochrone
fits indicate that FSR 1716 is more probably an old ( Gyr) and absorbed
(\aV=6.3\pm0.2) open cluster, located kpc inside the Solar
circle in a contaminated central field. However, we cannot rule out the
possibility of a low-mass, loose globular cluster. Czernik 23 is shown to be an
almost absorption-free open cluster, Gyr old, located about 2.5 kpc
towards the anti-centre. In both cases, Solar and sub-Solar ()
metallicity isochrones represent equally well the stellar sequences. Both star
clusters have a low mass content (\la200 \ms) presently stored in stars.
Their relatively small core and cluster radii are comparable to those of other
open clusters of similar age. These structural parameters are probably
consequence of the several Gyrs of mass loss due to stellar evolution, tidal
interactions with the disk (and bulge in the case of FSR 1716), and possibly
giant molecular clouds. Czernik 23, and especially FSR 1716, are rare examples
of extreme dynamical survivors. The identification of both as such represents
an increase of to the known population of open clusters older than
Gyr in the Galaxy.Comment: 15 pages and 13 figures. Accepted by A&
Exploring concepts of health with male prisoners in three category-C English prisons
Lay understandings of health and illness have a well established track record and a plethora of research now exists which has examined these issues. However, there is a dearth of research which has examined the perspectives of those who are imprisoned. This paper attempts to address this research gap. The paper is timely given that calls have been made to examine lay perspectives in different geographical locations and a need to re-examine health promotion approaches in prison settings. Qualitative data from thirty-six male sentenced prisoners from three prisons in England were collected. The data was analysed in accordance with Attride-Stirling's (2001) thematic network approach. Although the men's perceptions of health were broadly similar to the general population, some interesting findings emerged which were directly related to prison life and its associated structures. These included access to the outdoors and time out of their prison cell, as well as maintaining relationships with family members through visits. The paper proposes that prisoners' lay views should be given higher priority given that prison health has traditionally been associated with medical treatment and the bio-medical paradigm more generally. It also suggests that in order to fulfil the World Health Organization's (WHO) vision of viewing prisons as health promoting settings, lay views should be recognised to shape future health promotion policy and practice
The star cluster formation history of the LMC
The Large Magellanic Cloud is one of the nearest galaxies to us and is one of
only few galaxies where the star formation history can be determined from
studying resolved stellar populations. We have compiled a new catalogue of
ages, luminosities and masses of LMC star clusters and used it to determine the
age distribution and dissolution rate of LMC star clusters. We find that the
frequency of massive clusters with masses M>5000 Msun is almost constant
between 10 and 200 Myr, showing that the influence of residual gas expulsion is
limited to the first 10 Myr of cluster evolution or clusters less massive than
5000 Msun. Comparing the cluster frequency in that interval with the absolute
star formation rate, we find that about 15% of all stars in the LMC were formed
in long-lived star clusters that survive for more than 10 Myr. We also find
that the mass function of LMC clusters younger than 1 Gyr can be fitted by a
power-law mass function with slope \alpha=-2.3, while older clusters follow a
significantly shallower slope and interpret this is a sign of the ongoing
dissolution of low-mass clusters. Our data shows that for ages older than 200
Myr, about 90% of all clusters are lost per dex of lifetime. The implied
cluster dissolution rate is significantly faster than that based on analytic
estimates and N-body simulations. Our cluster age data finally shows evidence
for a burst in cluster formation about 1 Gyr ago, but little evidence for
bursts at other ages.Comment: 18 pages, 6 figures, MNRAS in pres
Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being
This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics
The Behavior of Novae Light Curves Before Eruption
In 1975, E. R. Robinson conducted the hallmark study of the behavior of
classical nova light curves before eruption, and this work has now become part
of the standard knowledge of novae. He made three points; that 5 out of 11
novae showed pre-eruption rises in the years before eruption, that one nova
(V446 Her) showed drastic changes in the variability across eruptions, and that
all but one of the novae (excepting BT Mon) have the same quiescent magnitudes
before and after the outburst. This work has not been tested since it came out.
We have now tested these results by going back to the original archival
photographic plates and measuring large numbers of pre-eruption magnitudes for
many novae using comparison stars on a modern magnitude scale. We find in
particular that four out of five claimed pre-eruption rises are due to simple
mistakes in the old literature, that V446 Her has the same amplitude of
variations across its 1960 eruption, and that BT Mon has essentially unchanged
brightness across its 1939 eruption. Out of 22 nova eruptions, we find two
confirmed cases of significant pre-eruption rises (for V533 Her and V1500 Cyg),
while T CrB has a deep pre-eruption dip. These events are a challenge to
theorists. We find no significant cases of changes in variability across 27
nova eruptions beyond what is expected due to the usual fluctuations seen in
novae away from eruptions. For 30 classical novae plus 19 eruptions from 6
recurrent novae, we find that the average change in magnitude from before the
eruption to long after the eruption is 0.0 mag. However, we do find five novae
(V723 Cas, V1500 Cyg, V1974 Cyg, V4633 Sgr, and RW UMi) that have significantly
large changes, in that the post-eruption quiescent brightness level is over ten
times brighter than the pre-eruption level.Comment: 91 pages (preprint), AJ accepte
Japanese Encephalitis—A Pathological and Clinical Perspective
Japanese encephalitis (JE) is the leading form of viral encephalitis in Asia. It is caused by the JE virus (JEV), which belongs to the family Flaviviridae. JEV is endemic to many parts of Asia, where periodic outbreaks take hundreds of lives. Despite the catastrophes it causes, JE has remained a tropical disease uncommon in the West. With rapid globalization and climatic shift, JEV has started to emerge in areas where the threat was previously unknown. Scientific evidence predicts that JEV will soon become a global pathogen and cause of worldwide pandemics. Although some research documents JEV pathogenesis and drug discovery, worldwide awareness of the need for extensive research to deal with JE is still lacking. This review focuses on the exigency of developing a worldwide effort to acknowledge the prime importance of performing an extensive study of this thus far neglected tropical viral disease. This review also outlines the pathogenesis, the scientific efforts channeled into develop a therapy, and the outlook for a possible future breakthrough addressing this killer disease
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