986 research outputs found
SOLID PHASE SYNTHESIS OF FLUORESCENT DYE LIBRARIES AND THEIR APPLICATIONS IN BIO-IMAGING
Ph.DDOCTOR OF PHILOSOPH
Improved infrared photoluminescence characteristics from circularly ordered self-assembled Ge islands
The formation of circularly ordered Ge-islands on Si(001) has been achieved because of nonuniform strain field around the periphery of the holes patterned by focused ion beam in combination with a self-assembled growth using molecular beam epitaxy. The photoluminescence (PL) spectra obtained from patterned areas (i.e., ordered islands) show a significant signal enhancement, which sustained till 200 K, without any vertical stacking of islands. The origin of two activation energies in temperature-dependent PL spectra of the ordered islands has been explained in detail
Cosmology in a Time-Crystal Background
We investigate the effects of a Time Crystal-like Condensate on cosmological
dynamics. It is well known that quadratic gravity reduces to Einstein gravity
along with a decoupled higher derivative dynamical scalar
\cite{Alvarez-Gaume:2015rwa}. According to \cite{Chakraborty:2020ktp}, the
above scalar sector can sustain a Time Crystal-like minimum energy state, with
non-trivial time dependence. In the present work we treat the Time Crystal-like
state as the background (that replaces the classical Minkowski vacuum) and
study cosmic evolution on this ``dynamic'' ground state. In the first part we
re-derive \cite{Chakraborty:2020ktp}, in a covariant and more systematic way,
the frequencies that characterize the oscillator like Time crystalline
condensate and interpret it as a background energy-momentum tensor simulating a
matter-like effect. Importantly, no external matter is introduced here and the
condensate, consists of a combination of the metric field and is
generated due to the -term ( is the Ricci scalar) in quadratic gravity
\cite{Alvarez-Gaume:2015rwa}. In a way the spurious degrees of freedom of
-gravity turns into a useful component. The second part comprises of new
effects where the cosmology in Friedmann-Lem\^{i}atre-Robertson-Walker (FLRW)
universe is studied in presence of the energy-momentum tensor characterizing
the Time Crystal Condensate. Under certain approximations, the scale factor of
the FLRW universe is analytically obtained for any spatial geometry. We also
find that the Time Crystal Condensate contributes as a new matter candidate
having radiation-like behavior in the universe. Additionally, irrespective of
the spatial geometry of the universe, the Time Crystal condensate generates a
decelerating phase before the early acceleration starts. This is an indication
of a contracting phase of the universe before its accelerated expansion.Comment: 11 pages, 4 compound figures. Comments are welcom
The detection of possible transient Quasi-Periodic Oscillations in the -ray light curve of PKS 0244-470 and 4C+38.41
The continuous monitoring capability of Fermi-LAT has enabled the exploration
of Quasi-Periodic Oscillations (QPOs) in the -ray light curve of blazar
that has given a new perspective to probe these source and jet physics over a
wide range of time scales. We report the presence of transient QPOs in the
long-term -ray light curve of blazars PKS 0244-470 \& 4C +38.41. We
first identified different flux states using the Bayesian Block algorithm and
then explored the possible transient QPOs in the segments of each flux phase
where the flux level changes over fairly regular intervals. Combining this with
source intrinsic variance, we identified two flux phases for PKS 0244-470: one
activity (AP-1) and one quiescent phase (QP-1). For 4C+38.41, we similarly
identified four activity (AP-1, AP-2, AP-3, and AP-4) and two quiescent (QP-1
and QP-2) phases. AP-1 phase of PKS 0244-470 shows QPO of 225 days
persisting for 8 cycles ( 4.1 ). In 4C+38.41, AP-1 and AP-2
phases show QPO of 110 days and 60 days, respectively, persisting
for 5 cycles. In AP-3, we identified three sub-phases, and all show a
week scale recurrent rise with five complete cycles, while in QP-1, we could
identify 2 sub-phases (Q1 and Q2). Q1 phase shows a significant period of
104 days with six complete cycles. Q2 phase also shows significant QPO
but with only 3.7 cycles. All the detections are locally significant
with at least four or more cycles. We discuss the possible origin and argue
that the current driven kink instability and curved jet model seem the most
likely cause for shorter and longer QPOs though the latter requires continuous
acceleration or injection of particles to explain these
Repurposing of Glycine-Rich Proteins in Abiotic and Biotic Stresses in the Lone-Star Tick (\u3ci\u3eAmblyomma americanum\u3c/i\u3e)
Tick feeding requires the secretion of a huge number of pharmacologically dynamic proteins and other molecules which are vital for the formation of the cement cone, the establishment of the blood pool and to counter against the host immune response. Glycine-rich proteins (GRP) are found in many organisms and can function in a variety of cellular processes and structures. The functional characterization of the GRPs in the tick salivary glands has not been elucidated. GRPs have been found to play a role in the formation of the cement cone; however, new evidence suggests repurposing of GRPs in the tick physiology. In this study, an RNA interference approach was utilized to silence two glycine-rich protein genes expressed in early phase of tick feeding to determine their functional role in tick hematophagy, cement cone structure, and microbial homeostasis within the tick host. Additionally, the transcriptional regulation of GRPs was determined after exposure to biotic and abiotic stresses including cold and hot temperature, injury, and oxidative stress. This caused a significant up-regulation of AamerSigP-34358, Aam-40766, AamerSigP-39259, and Aam-36909. Our results suggest ticks repurpose these proteins and further functional characterization of GRPs may help to design novel molecular strategies to disrupt the homeostasis and the pathogen transmission
Biofortification of Rice, An Impactful Strategy for Nutritional Security: Current Perspectives and Future Prospect
Globally, especially in the developing world, an estimated 20,000 million people are affected by micronutrient deficiency, generally named “hidden hunger.” Crop biofortification is an impactful strategy in addressing nutritional security as well as providing a cost-saving, sustainable means by uplifting health and well-being to communities with deprived access to diversified foods and interventions regarding the micronutrient supply. Considering the global concerns about micronutrient deficiency, research organizations have initiated studies on ensuring the bioavailability of micronutrients in staple food crops. Mitigating hidden hunger with the biofortification of rice surely can be a beneficial strategy for people who consumes rice as a staple food. Significant enhancement in iron and zinc levels, as well as with other essential minerals and vitamins is achieved in rice biofortification by various approaches. Adoption of biofortified rice varieties in targeted countries would significantly increase daily micronutrient intake and help to holistically alleviate malnutrition in human populations. This review articulates the status and perspective of rice biofortification as well as summarizes dissemination and adoption along with trends in consumer acceptance. With a positive trend, attention should now need shift to an action-based agenda and robust policy directives for scaling up rice biofortification in improving nutritional security for humans
Quasi-periodic oscillation detected in -rays in blazar PKS 0346-27
We present a variability study of the blazar PKS 0346-27 from December 2018
to January 2022 in its archival -ray observation by Fermi-LAT. We use
the Lomb-Scargle periodogram and the weighted wavelet transform methods in
order to detect the presence of periodicity/quasi-periodicity and localize this
feature in time and frequency space. The significance of the periodicity
feature has been estimated using the Monte-Carlo simulation approach. We have
also determined the global significance of the periodicity to test the
robustness of our claim. To explore the most probable scenario, we modeled the
light curve with both a straight jet and a curved jet model. We detect a
periodicity feature of 100 days duration for the entire period of
observation with a statistical significance of , which amounts to a
99.7\% confidence level. The global significance of this feature is found to be
96.96\%. Based on the Akaike Information Criteria, the most probable
explanation is that the observed emission is enhanced due to the helical motion
of a blob within a curved jet. The origin of this QPO is very likely a region
of enhanced emission moving helically inside a curved jet. This work presents
strong evidence for jet curvature in the source and an independent (albeit a
little serendipitous) procedure to estimate the curvature in blazar jets.Comment: 7 pages, 4 figures, Accepted for publication in A&A, in Pres
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