National issues raised by IIMA study on development and management of freshwater aquaculture in India: a review

An examination is made of various issues regarding freshwater aquaculture development raised by the IIMA study on inland fish marketing in India. The following topics are discussed: 1)fish production and the resources; 2)desirability for refined methodology for assessment of fish production; 3)pond resource under fish culture; 4)conflicting data and 5)observation on research input for freshwater

Student understanding of the direction of force due to atmospheric pressure: A tale of two models

The direction of force due to atmospheric pressure is a difficult idea for students to understand. We report a study, involving 35 middle school students, which points towards the existence of two contrasting mental models of atmospheric pressure(Patm), which we term the Weight Model (WM) and the Collision Model (CM). Our analysis reveals a predisposition among students to adhere to the WM, wherein they consider Patm akin to a column of air pressing down on the surface of the earth (Tytler,1998). In our presentation, we discuss everyday experiences and textbook presentations as two plausible sources for this predisposition. Our study involves the analysis of the student discourse as they participated in an activity to estimate the value of atmospheric pressure using a syringe and some easily available materials (Inversin, 1977). Students worked in small groups of 3 to 4, facilitated by instructors. Our goal was to help students engage in discussion, wherein they explicitly articulated their ideas and considered notions from others in an authentic context, thereby paving the way for a revision of their own ideas. The activity had the following components: a) A pre-activity questionnaire: A set of 6 questions, aimed at eliciting students’ prior conceptions and basic understanding related to atmospheric pressure. These written responses subsequently served as the basis for discussion among students, within and across student groups. b) A demonstration to show the action of atmospheric pressure: Instructors illustrated the action of atmospheric pressure on the syringe and its directionality. The demonstration sought to scaffold students’ thinking while engaging with the difficult notion of the direction of force due to atmospheric pressure. c) Activity to estimate the magnitude of atmospheric pressure: In this part the students have to design an experiment using the syringe to calculate the value of atmospheric pressure. The experimental design involves a balancing condition between 3 forces: static friction between the barrel and piston of the syringe, force due to atmospheric pressure and weight hung on the syringe. d) Post activity questionnaire: The final part of the activity is a set of questions aimed at checking whether there was any change in student response patterns pertaining to atmospheric pressure. Our analysis reveals that the activity and associated discussions show potential to facilitate students’ transition from the WM to the CM. We present evidence of modest conceptual gains characterized by micro-transitions in students’ problem-solving strategies, being increasingly inclined towards the canonical CM rather than the intuitive WM of the atmosphere. We also present some problematic discourse patterns, which are likely widespread in traditional lecture-based Physics classrooms. REFERENCES Inversin, A. R. (1977). Measuring Atmospheric Pressure with a Syringe. Physics Teacher, 15(4), 232-233. Tytler, R. (1998). Children’s conceptions of air pressure: Exploring the nature of conceptual change. International Journal of Science Education, 20(8), 929–958. https://doi.org/10.1080/095006998020080

Production oriented survey (POS) on different aspects of rice cultivation and farmers practices under red and lateritic zone of West Bengal, India

Production Oriented Survey (POS) on rice cultivation was conducted by Rice Research Station, Bankura under programme of AICRIP, Directorate of Rice Research (ICAR), Rajendranagar, Hyderabad – 50003 during kharif, 2009 in Red and Laterite zone of West Bengal, India. Purulia, Bankura and some parts of Birbhum, Paschim Medinipur and Burtdwan districts that belongs to Red and Laterite zone of West Bengal. The popular commercial cultivars were Swarna (MTU 7029), Lalat, Jaya, CR 1010, CR 1017 and IR-64.  Rice is cultivated as mono crop in this zone. The Indian sub-continent is predominantly characterized by a tropical monsoon climate which determines the success of kharif crops. Biotic constraints like blast, brown spot, sheath blight, sheath rot, grain dis-colouration and bacterial leaf blight (BLB) were in low to moderate intensities. Among insect pests brown plant hopper, green leaf hopper, stem borer, rice hispa and gundhi bugs were recorded in low to moderate intensities in the surveyed districts. Among weeds, Cyperus rotundus, Echinocloa crusgalli, Cyperus iria, Cynodon dactylan and Monochoria sp.  were major problem in all the districts. The farmers used mainly hand weeding for control of weeds. Minimum use of pesticides and insecticides were observed

Wormhole with varying cosmological constant

It has been suggested that the cosmological constant is a variable dynamical quantity. A class of solution has been presented for the spherically symmetric space time describing wormholes by assuming the erstwhile cosmological constant $\Lambda$ to be a space variable scalar, viz., $\Lambda$ = $\Lambda (r)$ . It is shown that the Averaged Null Energy Condition (ANEC) violating exotic matter can be made arbitrarily small.Comment: 8 pages, 2 figures, Accepted in Gen. Rel. Gra

Thermodynamics of the PNJL model

QCD thermodynamics is investigated by means of the Polyakov-loop-extended Nambu Jona-Lasinio (PNJL) model, in which quarks couple simultaneously to the chiral condensate and to a background temporal gauge field representing Polyakov loop dynamics. The behaviour of the Polyakov loop as a function of temperature is obtained by minimizing the thermodynamic potential of the system. A Taylor series expansion of the pressure is performed. Pressure difference and quark number density are then evaluated up to sixth order in quark chemical potential, and compared to the corresponding lattice data. The validity of the Taylor expansion is discussed within our model, through a comparison between the full results and the truncated ones.Comment: 6 pages, 5 figures, Talk given at the Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions (Hot Quarks 2006), Villasimius, Italy, 15-20 May 200

Gravitational Lensing by Black Holes

We review the theoretical aspects of gravitational lensing by black holes, and discuss the perspectives for realistic observations. We will first treat lensing by spherically symmetric black holes, in which the formation of infinite sequences of higher order images emerges in the clearest way. We will then consider the effects of the spin of the black hole, with the formation of giant higher order caustics and multiple images. Finally, we will consider the perspectives for observations of black hole lensing, from the detection of secondary images of stellar sources and spots on the accretion disk to the interpretation of iron K-lines and direct imaging of the shadow of the black hole.Comment: Invited article for the GRG special issue on lensing (P. Jetzer, Y. Mellier and V. Perlick Eds.). 31 pages, 12 figure

Biallelic Mutations in ADPRHL2, Encoding ADP-Ribosylhydrolase 3, Lead to a Degenerative Pediatric Stress-Induced Epileptic Ataxia Syndrome.

ADP-ribosylation, the addition of poly-ADP ribose (PAR) onto proteins, is a response signal to cellular challenges, such as excitotoxicity or oxidative stress. This process is catalyzed by a group of enzymes referred to as poly(ADP-ribose) polymerases (PARPs). Because the accumulation of proteins with this modification results in cell death, its negative regulation restores cellular homeostasis: a process mediated by poly-ADP ribose glycohydrolases (PARGs) and ADP-ribosylhydrolase proteins (ARHs). Using linkage analysis and exome or genome sequencing, we identified recessive inactivating mutations in ADPRHL2 in six families. Affected individuals exhibited a pediatric-onset neurodegenerative disorder with progressive brain atrophy, developmental regression, and seizures in association with periods of stress, such as infections. Loss of the Drosophila paralog Parg showed lethality in response to oxidative challenge that was rescued by human ADPRHL2, suggesting functional conservation. Pharmacological inhibition of PARP also rescued the phenotype, suggesting the possibility of postnatal treatment for this genetic condition

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

The inclusive transverse momentum ($p_{\rm T}$) distributions of primary charged particles are measured in the pseudo-rapidity range $|\eta|<0.8$ as a function of event centrality in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=2.76$ TeV with ALICE at the LHC. The data are presented in the $p_{\rm T}$ range $0.15<p_{\rm T}<50$ GeV/$c$ for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor $R_{\rm{AA}}$ using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-$p_{\rm T}$ particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with $R_{\rm{AA}}\approx0.13$ at $p_{\rm T}=6$-7 GeV/$c$. Above $p_{\rm T}=7$ GeV/$c$, there is a significant rise in the nuclear modification factor, which reaches $R_{\rm{AA}} \approx0.4$ for $p_{\rm T}>30$ GeV/$c$. In peripheral collisions (70-80%), the suppression is weaker with $R_{\rm{AA}} \approx 0.7$ almost independently of $p_{\rm T}$. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

Measurement of charm production at central rapidity in proton-proton collisions at s=2.76\sqrt{s} = 2.76 TeV

The $p_{\rm T}$-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D$^0$, D$^+$, and D$^{*+}$ in the rapidity range $|y|<0.5$, and for transverse momentum $1< p_{\rm T} <12$ GeV/$c$, were measured in proton-proton collisions at $\sqrt{s} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D$^0 \rightarrow$K$\pi$, D$^+ \rightarrow$K$\pi\pi$, D$^{*+} \rightarrow$D$^0\pi$, and their charge conjugates, and was performed on a $L_{\rm int} = 1.1$ nb$^{-1}$ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $\sqrt{s} = 2.76$ TeV and at 7 TeV was evaluated by extrapolating to the full phase space the $p_{\rm T}$-differential production cross sections at $\sqrt{s} = 2.76$ TeV and our previous measurements at $\sqrt{s} = 7$ TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/307