1,564 research outputs found
Marine phenology and its response to climate change -Winter School on Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008
Phenology is defined as the study of the timing of recurring biological phases, the causes of their
timing with regard to biotic and abiotic forces, and the interrelation among phases of the same or different
species. In other words it is the study of plant and animal life cycle events, which are triggered by
environmental changes, especially temperature. The word “phenology” is derived from the Greek Phainomai,
which means “to appear” or “come into view”, and indicates that phenology has been principally concerned
with the dates of first occurrence of natural events in their annual cycle
Marine pollution
Pollution is a big problem that has impact on all of the
planet's ecosystems, including the oceans. Economic
developement has been most active In coastal zones, putting
enormous pressure on coastal ecosystems. Marine pollution
has Increased throughout the world, mainly due to direct discharges
from rivers, increased surface run-off and drainage
from expanding port areas, oil spills and other contaminants
from shipping and domestic and industrial effluent. Most of the
world's wastes-some 20 billion tonnes of it a year-end up in the
sea, often without any preliminary processing
Marine pollution monitoring using mussels
Pollution is a major problem that has negative effects on all of the planet’s ecosystems, including
the oceans. In many parts of the region, economic development has been most active in coastal
zones, putting enormous pressures on coastal ecosystems. Coastal and marine water pollution has
increased throughout the world, mainly due to direct discharges from rivers, increased surface
rim-off and drainage from expanding port areas, oil spil sand other contaminants from shipping,
and domestic and industrial effluent
Estimation of secondary production & benthos- Winter School on Towards Ecosystem Based Management of Marine Fisheries – Building Mass Balance Trophic and Simulation Models
Marine organisms can be categorized as benthic, planktonic or nektonic depending on
their physical habitat and their mode of motility. Planktonic organisms are those that live
suspended in the water column and that are sufficiently small and/or slow so as to be
incapable of directed swimming. Thus, their distribution is considered to be controlled by
physical processes, such as water currents and turbulent mixing. In addition, plankton can be
divided further based on their nutritional modality. Autotrophic phytoplankton depends on
light and chlorophyll to fix carbon dioxide into organic molecules, whereas heterotrophic
zooplankton ultimately depends on the phytoplankton for their dissolved or particulate
foodstuffs
Climate change related marine ecosystem regime shifts and their impact on fisheries -Winter School on Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008
Global changes affect the biotic and abiotic elements that influence the numbers and distribution of
fish species. It is now understood that marine ecosystems change on a variety of time scales, from seasonal
to centennial and longer. Atmospheric and climate-related processes force many of these time scales, and
therefore it is well understood by marine scientists that climate variability is a strong driver of changes in
fish populations and in fisheries
Primer software and its application in marine biodiversity studies. In: Winter School on Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008
The PRIMER (Plymouth Routines In Multivariate Ecological Research) software was developed by
Dr. Bob Clarke and Dr. Ray Gorley of Plymouth Marine Laboratory, UK (Clarke and Warwick, 1994). This
software can perform analysis of ecological data entered in spreadsheets. It can be used for calculating
various univariate biodiversity measures such as Margalef’s index, Shannon-Weiner index, Brillouin’s index,
Simpson diversity index etc. The latest version of the software (PRIMER 6) consists of a wide range of
univariate, graphical and multivariate routines for analysing the species/samples abundance (or biomass)
matrices that arise in biological monitoring of environmental impact and more fundamental studies in
community ecology, together with associated physico-chemical data. The methods make few, if any,
assumptions about the form of the data (‘non-metric’ ordination and permutation tests are fundamental to
the approach) and concentrate on approaches that are straightforward to understand and explain
Multi-frequency scatter broadening evolution of pulsars - I
We present multi-wavelength scatter broadening observations of 47 pulsars,
made with the Giant Metre-wave Radio Telescope (GMRT), Ooty Radio Telescope
(ORT) and Long Wavelength Array (LWA). The GMRT observations have been made in
the phased array mode at 148, 234, and 610 MHz and the ORT observations at 327
MHz. The LWA data sets have been obtained from the LWA pulsar data archive. The
broadening of each pulsar as a function of observing frequency provides the
frequency scaling index, . The estimations of have been
obtained for 39 pulsars, which include entirely new estimates for 31 pulsars.
This study increases the total sample of pulsars available with
estimates by 50\%. The overall distribution of with the
dispersion measure (DM) of pulsar shows interesting variations, which are
consistent with the earlier studies. However, for a given value of DM a range
of values are observed, indicating the characteristic turbulence along
each line of sight. For each pulsar, the estimated level of turbulence,
, has also been compared with and DM. Additionally, we
compare the distribution of with the theoretically predicated model to
infer the general characteristics of the ionized interstellar medium (ISM).
Nearly 65\% of the pulsars show a flatter index (i.e., ) than
that is expected from the Kolmogorov turbulence model. Moreover, the group of
pulsars having flatter index is typically associated with an enhanced value of
than those with steeper index.Comment: 13 pages, 4 figures, 3 tables. Accepted for publication in Ap
Lie Symmetry Analysis of the Black-Scholes-Merton Model for European Options with Stochastic Volatility
We perform a classification of the Lie point symmetries for the
Black--Scholes--Merton Model for European options with stochastic volatility,
, in which the last is defined by a stochastic differential equation
with an Orstein--Uhlenbeck term. In this model, the value of the option is
given by a linear (1 + 2) evolution partial differential equation in which the
price of the option depends upon two independent variables, the value of the
underlying asset, , and a new variable, . We find that for arbitrary
functional form of the volatility, , the (1 + 2) evolution equation
always admits two Lie point symmetries in addition to the automatic linear
symmetry and the infinite number of solution symmetries. However, when
and as the price of the option depends upon the second
Brownian motion in which the volatility is defined, the (1 + 2) evolution is
not reduced to the Black--Scholes--Merton Equation, the model admits five Lie
point symmetries in addition to the linear symmetry and the infinite number of
solution symmetries. We apply the zeroth-order invariants of the Lie symmetries
and we reduce the (1 + 2) evolution equation to a linear second-order ordinary
differential equation. Finally, we study two models of special interest, the
Heston model and the Stein--Stein model.Comment: Published version, 14pages, 4 figure
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