Siddhartha Mitra

East Carolina University | ECU · Department of Geological Sciences

1] Small mountainous rivers (SMRs) export substantial amounts of sediment into the world's oceans. The concomitant yield of organic carbon (OC) associated with this class of rivers has also been shown to be significant and compositionally unique. We report here excessively high loadings of polycyclic aromatic hydrocarbons (PAHs), lignin, and levogl...

In bioavailability studies, the biota sediment accumulation factor (BSAF) is invoked to describe the thermodynamic partitioning of a hydrophobic organic contaminant (HOC) between the organism lipid and the organic carbon fraction of the sedimentary matrix and accounts for differences in bioavailability among sediments. Bioaccumulation experiments w...

Biota-sediment accumulation factors (BSAF) were calculated for Diporeia spp. and oligochaete worms exposed to polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from field-collected sediment. These data were compared to the contaminant fraction extracted from sediment with Tenax resin using a 24 h extraction. A previous la...

The source characterization of a Flash X-ray (FXR) device is essential in defining its utility for dynamic radiography. A Marx generator [550 kV, $50~\Omega $ , and 45 ns full-width half-maxima (FWHM)] based FXR source operating in the voltage range 200–550 kV has been characterized. The FXR electron beam diode has a cylindrical geometry with sta...

Pamlico Sound, a large back-barrier estuary in North Carolina, is under threat of climate change due to increased storm activity and sea-level rise. The response of this system is investigated by considering what has already happened during changes in sea-level over the late Holocene epoch. The hydrodynamic changes that occurred in response to geom...

find the full paper at https://authors.elsevier.com/a/1Wo16B8ccgX~R The age and ability of salt marshes to accumulate and sequester carbon is often assessed using the carbon isotopic signatures (Δ14C and δ13C) of sedimentary organic matter. However, transfers of allochthonous refractory carbon (CRF) from the watershed to marshes would not represen...

Barrier islands and associated back-barrier estuaries and lagoons interact via hydrodynamic and sedimentary processes, affecting the evolution of both systems. Understanding coupled dynamic processes between both systems is vital to forecasts of future coastal morphologic and hydrodynamic changes in response to such factors as sea-level rise and st...

Flash X-ray sources driven by pulsed power find applications in industrial radiography, and a portable X-ray source is ideal where the radiography needs to be taken at the test site. A compact and portable flash X-ray (FXR) system based on a Marx generator has been developed with the high voltage fed to the FXR tube via a cable feed-through arrange...

COSMA: Coherent Optics Sensors for Medical Application is an European Marie Curie Project running from 2012 to March 2016, with the participation of 10 teams from Armenia, Bulgaria, India, Israel, Italy, Poland, Russia, UK, USA. The main objective was to focus theoretical and experimental research on biomagnetism phenomena, with the specific aim to...

Relativistic backward wave oscillators (RBWO) are widely used high power microwave (HPM) devices due to their ease of operation and simple geometry. This paper presents the RBWO power generation experiments carried out on KALI 30 GW pulse power system. We have used 600 kV, 7 kA electron beam to generate 0.8 GW HPM power with 3.28 GHz frequency. A m...

Primary debris found in an Iron Age bath-shaped vessel excavated from Zincirli, ancient Sam'al, Turkey, was subjected to organic residue analysis by gas chromatography–mass spectrometry (GC–MS). Bath-shaped vessels are usually interpreted as burial coffins, but recently these vessels have been linked to crafts manufacture, specifically wool process...

This study examines the Holocene stratigraphic record and paleoenvironmental evolution of a large estuarine system, at high temporal and spatial resolution, in the context of changing climate, sea level, and hydrodynamics. New data are used to examine two time periods of increased marine influence within Pamlico Sound in northeastern North Carolina...

The presence of a dark stratal layer, known as Younger Dryas black mat, has been reported globally at many different sites. Samples of this black mat have been carbon dated to approximately 12,800 years BP, which coincides with the Younger Dryas Stadial, a period of extensive cooling. One hypothesis for the presence of the black mat layer is that a...

A numerical model was used to simulate water levels, currents, waves, suspended sediment and salinity distributions in Pamlico Sound, a large and shallow back-barrier estuary in eastern North Carolina, for four distinct time slices during its geomorphic evolution over the late Holocene. Present-day bathymetry was obtained from a high resolution dig...

This paper reports the design methodology and implementation experiments for a solid-state-based triggering arrangement for the MARX generator of the KALI-30GW (1 MV, 30 kA, 80 ns) pulsed power system. The 15-stage bipolar MARX generator of the KALI-30GW system is triggered using a trigatron-type spark gap. An insulated-gate bipolar-transistor (IGB...

The pump-probe spectra in a cell of micrometric thickness containing cesium vapor are reported. The line shape and nonlinear features observed in the case of fluorescence in the direction parallel to the cell windows and the transmission spectra observed along the propagation direction of the probe beam show considerable differences in the spectral...

This paper elaborates the effect of unmatched stored energy in high-voltage high-energy pulsed power systems. High-voltage insulation failure of KALI system is analyzed thoroughly for its occurrence. According to the simulations and analysis energy mismatch of MARX generator and Blumlein transmission line is found to be the most significant cause f...

An ephemeral oceanic-flood deposit adjacent to a well-studied small mountainous river (SMR), the Waipaoa River in northeastern New Zealand, was characterized using multiple proxies, including radioisotopes (234Th, 7Be, and 210Pb), bulk organic carbon abundance and isotopic signature (%OC, δ13C), as well as a biomarker of terrigenous organic matter...

A 40kJ, 20kV Electromagnetic Manufacturing (EMM) system [1] has been developed for forming and welding of various metals. The EMM consists of four energy storage capacitor based sub-banks, constant current charging variable dc power supply, single type spark gaps (TSG) switches. Four switches are used, one for each sub-bank. A trigger generator [2,...

High current intense electron beams were investigated earlier for Flash X-rays and nuclear electromagnetic pulse generation. Starting with moderate parameters of 200 kV, 6 kA, 60 ns pulsed electron beam source from a system named Kilo Ampere Linear Injector (KALI-75) our latest development is KALI-30 GW system rated for 1 MV, 30 kA, 80 ns. First re...

DIG (Desmoplastic Infantile Ganglioglioma) is a rare intracranial neo-plasm classified as WHO grade I tumor under neuronal and mixed neuronal glial tumors (under 2007 World Health Organization brain tumor classification). It is usually considered to have a good prognosis but 40% of the cases require additional medical, radiation and/or further surg...

BACKGROUND: LMD in children with recurrent medulloblastoma and other PNETs carries a poor prognosis and novel therapies are urgently needed to improve disease control. Somatostatin receptor-2 (SSR-2)is overexpressed in medulloblastoma and other central PNETs and can serve as a target for radionuclide tagged somatostatin analogues like 177Lu-DOTA-TA...

On-site wastewater treatment systems (OWS) are a potentially significant non-point source of nutrients to groundwater and surface waters, and are extensively used in coastal North Carolina. The goal of this study was to determine the treatment efficiency of four OWS in reducing total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) conce...

In pulse power system, generation and measurement of fast rising, short duration, high voltage pulses is a challenging job, because of at high frequencies inductance of the circuit elements and their parasitic capacitances becomes effective at such level that they can change the desired characteristics of the generated pulse waveforms. A 50kV PFL (...

form only given. This paper analyses the phenomena of wave erection in a coaxially arranged fast erecting MARX generator for finding the importance of delayed sequential synchronization of spark gap switches. A wave propagation model of coaxially arranged MARX generator is made. Simulation shows, that generated output voltage and energy delivered t...

We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1–99M⊙...

Surface sediments were collected from the inner shelf of the highly dynamic East China Sea (ECS) in December 2009 and November 2010. In between the two cruises, a big flood event occurred in July, 2010. Elemental, stable C, N isotope, radiocarbon isotope (∆14C), black carbon (BC) analysis, and chemical biomarkers were utilized to study the effect o...

A multi-tracer approach was applied to particulate organic material (POM) biogeochemistry along a 165-km transect of the freshwater-tidal portion of the Hudson River estuary (HRE). Elemental carbon and nitrogen, stable isotopes, chlorophyll a, and lignin phenols were measured monthly at a mid-estuary station from August to November 2007, and monthl...

BACKGROUND: Pediatric Diffuse intrinsic pediatric glioma (DIPG) remained dismal regardless of the new therapeutic and technical attempts. PURPOSE: To investigate the efficacy and toxicity of hypofractionated radiotherapy in pediatric DIPG compared to conventional radiotherapy and to determine the prognostic factors for its overall (OS) and progress...

An inductive energy storage pulse power system is being developed in BARC, India. Simple, compact, and robust opening switches, capable of generating hundreds of kV, are key elements in the development of inductive energy storage pulsed power sources. It employs an inductive energy storage and opening switch power conditioning techniques with high...

Polycyclic aromatic hydrocarbon (PAH) biota-sediment accumulation factors (BSAF) were quantified in sediments from two sites in southeastern Louisiana in a 14 d microcosm study usingPalaemonetes pugio, andRangia cuneata and two radiolabeled PAHs, phenanthrene and benzo[a]pyrene (b[a]p). For both PAHs studied, mean BSAFs were significantly higher (p...

Mesozooplankton (>200 μm) collected in August and September of 2010 from the northern Gulf of Mexico show evidence of exposure to polycyclic aromatic hydrocarbons (PAHs). Multivariate statistical analysis revealed that distributions of PAHs extracted from mesozooplankton were related to the oil released from the ruptured British Petroleum Macondo-1...

This paper presents unsteady computational simulation results and supporting experimental evidence that show a certain fundamental feature of a purely shear driven annular/stratified internal condensing flow with respect to its sensitivity to boundary conditions. This feature is termed “elliptic sensitivity.” Shear driven condensing flows occur in...

A Post-Colonial settlement record of sedimentary black carbon (BC) from the Chesapeake Bay was used to reconstruct the impact of climate and anthropogenic activities on regional fire regime at multi-decadal time-scales. The abundance of BC in this sediment core varies between 0.21 - 0.75 % per gram of dry weight (gdw), while the abundance of OC var...

Tidal amplitude and currents along coastlines will change in conjunction with sea-level rise, when certain geomorphic and bathymetric conditions are met. Under conditions of decreasing protection from barrier islands, associated with increased inlet activity or overstepping of islands, tidal amplitude can rapidly increase in estuaries and along mai...

This paper presents a new high voltage pulse shaping methodology for pulsed power applications. The aim is to generate high voltage square pulse across anode cathode gap of e-beam diodes. The non-linear time varying perveance characteristics of e-beam diodes are used for shaping of output voltage pulse across it, generated directly from Marx genera...

In recent years, pulsed power systems have gained importance for the pulsed electron beam generation for industrial and defense applications. High voltage Energy storage capacitors were being used widely worldwide for the pulsed power system in electric field. In case of capacitive energy storage system, the size of the system is decided by capacit...

In micro-manufacturing, circularity of a drilled hole at entry and exit are important attributes which greatly influence the quality of a drilled hole. This study investigates the effect of five parameters in the circularity of drilled holes in pulsed Nd:YAG laser micro-drilling process. The drilling operation has been carried out on titanium nitri...

We report the results of the first search for gravitational waves from compact binary coalescence using data from the Laser Interferometer Gravitational-Wave Observatory and Virgo detectors. Five months of data were collected during the Laser Interferometer Gravitational-Wave Observatory’s S5 and Virgo’s VSR1 science runs. The search focused on sig...

Ethnomedicinal usages of 62 plant species commonly used by 11 tribal communities of North Bengal plain for the treatment of gastro-intestinal problems are provided. The plains of North Bengal is the northern part of West Bengal lying South of the hills of Darjeeling district and of Western Bhutan and stretches as far South as the river Ganga. This...

Sediment cores from the continental shelf adjacent to the Mississippi River delta immediately after the passage of Hurricane Katrina were used to examine the magnitude, and implications for the carbon budget, of sediment and particulate organic carbon (POC) remobilized by the storm on the river-dominated continental shelf. POC was sourced from inci...

We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia A. The search coherently analyzes data in a 12 day interval taken from the fifth science run of the Laser Interferometer Gravitational-Wave Observatory. It searches gravitational-wave frequencies from 100 to 300 Hz and covers a wide range...

Laser spectroscopy experiments are reported on rubidium atoms by using two or three external cavity diode lasers to study multiple resonance transitions in Lambda- and V-type systems as well as on (Lambda+V)-type system. Electromagnetically induced transparency (EIT) peaks having sub-natural line-widths are found on the Doppler broadened transmissi...

In this paper, an experimental investigation into laser transmission welding of acrylics is carried out. The Taguchi method of parameter design is used as a statistical design of experiment technique to set the optimal process parameters. Experiments are designed and conducted by using Taguchi's L16 orthogonal array. Maximization of weld strength i...

We present an up-to-date, comprehensive summary of the rates for all types of compact binary coalescence sources detectable by the initial and advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo. Astrophysical estimates for compact-binary coalescence rates depend on a number of assumptions and unknown model parameters...

We present a comparative study of the optical pumping process in four natural mixture Rb cells with different level of miniaturization. The influence of 2 Torr Ne gas added as buffer on the optical pumping is estimated using the fluorescence spectra on the Rb D2-line obtained by tunable single-mode circularly-polarized diode laser. The obtained res...

We report a precise frequency locking technique using electromagnetically induced transparency in an atomic vapour cell for a semiconductor diode laser. The sub natural line-width of EIT (Electromagnetically induced transparency) allows improvement in the stability of the laser diode under the locked condition. D2 transition of 85Rb atom is used fo...

Elemental carbon and nitrogen, stable isotopes, and lignin phenols were quantified for suspended particulate material exchanging between Tivoli Bays wetlands and the main stem of the freshwater-tidal Hudson River estuary (HRE) across a tidal cycle, seasonally in 2006 and monthly in 2007 during the ice-free portion of the year. Temporal shifts in or...

Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had...

Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had...

We present results from an all-sky search for unmodeled gravitational-wave bursts in the data collected by the LIGO, GEO 600 and Virgo detectors between November 2006 and October 2007. The search is performed by three different analysis algorithms over the frequency band 50–6000 Hz. Data are analyzed for times with at least two of the four LIGO-Vir...

We present a detail analysis of the line shape of electromagnetically induced transparency (EIT) in a Doppler broadened five level atomic system based on density matrix formalism. It has been shown that the velocity averaged EIT line shape in a multilevel system is very sharp. The effect of the ground state decay rates on the EIT peak has also been...

We report the experimental observations of double EIT and enhanced EIT signal in a combination of Λ- and V-type multi-level system of the D2 transition of 85Rb atoms interacting with three laser fields. The EIT formation under a Λ-type and V-type systems is also observed separately. It is found that the EIT width in a V-type system becomes narrower...

We present an up-to-date, comprehensive summary of the rates for all types of compact binary co-alescence sources detectable by the Initial and Advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo. Astrophysical estimates for compact-binary coalescence rates depend on a number of assumptions and unknown model parameters...

Selection of machining parameter combinations for obtaining optimum circularity at entry and exit and hole taper is a challenging task in laser microdrilling owing to the presence of a large number of process variables. There is no perfect combination of parameters that can simultaneously result in higher circularity at entry and exit and lower hol...

We present results from an all-sky search for unmodeled gravitational-wave bursts in the data collected by the LIGO, GEO 600 and Virgo detectors between November 2006 and October 2007. The search is performed by three different analysis algorithms over the frequency band 50-6000 Hz. Data are analyzed for times with at least two of the four LIGO-Vir...

Monomer dynamics in sodium dodecyl sulfate (SDS) micellar solution at room temperature as studied by quasi elastic neutron scattering (QENS) technique is reported. The elastic incoherent structure factor (EISF) obtained from the analysis of QENS data suggests that the SIDS chains perform uniaxial rotational diffusion along the long Molecular axis....

Here we report dynamics of propylene (smallest asymmetric hydrocarbon) adsorbed in two different host systems - Na-Y and Na-ZSM5 zeolites as studied by quasielastic neutron scattering (QENS) techniques and molecular dynamics (MD) simulation techniques. MD simulation studies Suggested that the rotational motion Of propylene is much faster than the t...

Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had...

We report the results of the first search for gravitational waves from compact binary coalescence using data from the Laser Interferometer Gravitational-Wave Observatory and Virgo detectors. Five months of data were collected during the Laser Interferometer Gravitational-Wave Observatory's S5 and Virgo's VSR1 science runs. The search focused on sig...