Local chromosome context is a major determinant of crossover pathway biochemistry during budding yeast meiosis

The budding yeast genome contains regions where meiotic recombination initiates more frequently than in others. This pattern parallels enrichment for the meiotic chromosome axis proteins Hop1 and Red1. These proteins are important for Spo11-catalyzed double strand break formation; their contribution to crossover recombination remains undefined. Using the sequencespecific VMA1-derived endonuclease (VDE) to initiate recombination in meiosis, we show that chromosome structure influences the choice of proteins that resolve recombination intermediates to form crossovers. At a Hop1-enriched locus, most VDE-initiated crossovers, like most Spo11- initiated crossovers, required the meiosis-specific MutLg resolvase. In contrast, at a locus with lower Hop1 occupancy, most VDE-initiated crossovers were MutLg-independent. In pch2 mutants, the two loci displayed similar Hop1 occupancy levels, and VDE-induced crossovers were similarly MutLg-dependent. We suggest that meiotic and mitotic recombination pathways coexist within meiotic cells, and that features of meiotic chromosome structure determine whether one or the other predominates in different regions

Comparative evaluation of traditional and improved cultivation practices and cultivars of Colocasia esculenta (L.) H. W. Schott in the Borail Hills Range of India

Present work was focused on the comparative evaluation of the Taro tuber productivity by using improved cultivation practices versus traditional cultivation practices. Initially, passport data of all the collected 27 cultivars and wild edible aroids were prepared and their Indigenous Collection Numbers (IC) were procured from the Indian Council of Agricultural Research-National Bureau of Plant Genetic Resources, New Delhi. All the collections were phytochemically evaluated and five variants of Colocasia esculenta (L.) H. W. Schott were found to be superior and their IC Numbers are 0631527, 0631529, 0631536, 0631544 and 0631546. Following the randomised block design method for crop productivity evaluation, data of five nutritionally superior cultivar and one check variety were taken in three replications (R1, R2, R3) from eighteen plots of measuring 5×5 m2 (25 m2). Taro tuber productivity in kg/plant from the first and second year’s data from the ICAR-NBPGR, Umiam and also the farmer’s data from Borail Hills Range were analysed by using SPSS software, and that shows significant difference among all the six treatments/variants under Critical Difference at 5% (CD 5%). Total of the data replications (R1+R2+R3) from first, second year data from ICAR-NBPGR, Umiam and also farmer’s data from Borail Hills Range are 18.24 kg, 19.45 kg and 12.69 kg respectively; clearly showing the tuber productivity enhancement of improved cultivation practices over the traditional agro- practices

Coexistence of magnetism and superconductivity in a t-J bilayer

We investigate coexistence of antiferromagnetic and superconducting correlations in bilayered materials using a two-dimensional t-J model with couplings across the layers using variational Monte Carlo calculations. It is found that the underdoped regime supports a coexisting phase, beyond which the (d-wave) superconducting state becomes stable. Further, the effects of interplanar coupling parameters on the magnetic and superconducting correlations as a function of hole doping are studied in details. The magnetic correlations are found to diminish with increasing interplanar hopping away from half filling, while the exchange across the layers strengthens interplanar antiferromagnetic correlations both at and away from half filling. The superconducting correlations show more interesting features where larger interplanar hopping considerably reduces planar correlations at optimal doping, while an opposite behaviour, i.e. stabilisation of the superconducting state is realised in the overdoped regime, with the interplanar exchange all the while playing a dormant role.Comment: 8 pages, 9 figures, RevTex4, Submitted to Phys. Rev.

The Barrier Method: A Technique for Calculating Very Long Transition Times

In many dynamical systems there is a large separation of time scales between typical events and "rare" events which can be the cases of interest. Rare-event rates are quite difficult to compute numerically, but they are of considerable practical importance in many fields: for example transition times in chemical physics and extinction times in epidemiology can be very long, but are quite important. We present a very fast numerical technique that can be used to find long transition times (very small rates) in low-dimensional systems, even if they lack detailed balance. We illustrate the method for a bistable non-equilibrium system introduced by Maier and Stein and a two-dimensional (in parameter space) epidemiology model.Comment: 20 pages, 8 figure

Physical Electronics and Surface Physics

Contains research objectives, summary of research and reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Aeronautics and Space Administration (Grant NGR 22-009-091

Multi-wavelength polarimetric study towards the open cluster NGC 1893

We present multi-wavelength linear polarimetric observations for 44 stars of the NGC 1893 young open cluster region along with V-band polarimetric observations of stars of other four open clusters located between l ~160 to ~175 degree. We found evidence for the presence of two dust layers located at a distance of ~170 pc and ~360 pc. The dust layers produce a polarization Pv ~2.2%. It is evident from the clusters studied in the present work that, in the Galactic longitude range l ~160 to 175 degree and within the Galactic plane (|b| < 2 degree), the polarization angles remain almost constant, with a mean ~163 degree and a dispersion of 6 degree. The small dispersion in polarization angle could be due to the presence of uniform dust layer beyond 1 kpc. Present observations reveal that in case of NGC 1893, the foreground two dust layers, in addition to the intracluster medium, seems to be responsible for the polarization effects. It is also found that towards the direction of NGC 1893, the dust layer that exists between 2-3 kpc has a negligible contribution towards the total observed polarization. The weighted mean for percentage of polarization (Pmax) and the wavelength at maximum polarization ({\lambda}max) are found to be 2.59 \pm 0.02% and 0.55 \pm 0.01 \mum respectively. The estimated mean value of {\lambda}max indicates that the average size of the dust grains within the cluster is similar to that in the general interstellar medium. The spatial variation of the polarization is found to decrease towards the outer region of the cluster. In the present work, we support the notion, as already has been shown in previous studies, that polarimetry, in combination with (U-B)/(B-V) colour-colour diagram, is a useful tool for identifying non-members in a cluster.Comment: 36 pages, 12 figures, 10 tables, accepted for the publication in MNRA

Yak Rearing on High Altitude Pastures of Northeastern Himalaya of India: Their Utilization Strategies and Rejuvenation

Yak rearing on alpine pastures is the main occupation of the highland pastoral nomads (Brokpa and Dokpas) of north-east (NE) India. These pastoral nomads living in the remote mountains solely rely on high altitude pastures for their nutritional and livelihood security because of virtual existence of agricultural activities in this area. They rear yaks under transhumance and utilize various pastures while migrating from low land winter pastures to high altitude alpine pastures during summer. Therefore, the temperate and alpine pastures are the major feed resources for the yaks. The indiscriminate use of pastures and impending climate change results in their degradation that may affect the productivity of the animals reared on them. In this study, an attempt was made to evaluate the status of pastures used for yak rearing in NE India and an initiative has been taken to test the adaptability of palatable high yielding temperate grasses for pasture development and rejuvenation

The Harmonic Measure for critical Potts clusters

We present a technique, which we call "etching," which we use to study the harmonic measure of Fortuin-Kasteleyn clusters in the Q-state Potts model for Q=1-4. The harmonic measure is the probability distribution of random walkers diffusing onto the perimeter of a cluster. We use etching to study regions of clusters which are extremely unlikely to be hit by random walkers, having hitting probabilities down to 10^(-4600). We find good agreement between the theoretical predictions of Duplantier and our numerical results for the generalized dimension D(q), including regions of small and negative q.Comment: 20 pages, 10 figure

Evaluation of mulberry tree leaves based diets in Corriedale lambs

An experiment was conducted in two phases; phase-I, five experimental rations were prepared with incorporation of mulberry leaf meals replacing concentrates @ 0% (C), 20% (TR1), 40% (TR2), 60% (TR3) and 80% (TR4), respectively and TR4 was found the best in terms of IVDM, IVOM and IVNDF digestibility. In phase-II, TR4 was made in two forms, mash and CFBs and were fed to six corriedale lambs in group T1 and T2, respectively. The control group (C) was fed with conventional ration prepared in mash form as per NRC 1985. The fortnightly dry matter intake expressed as per cent of body weight in C, T1 and T2 groups were 3.77, 3.90 and 4.07, respectively, and were statistically significant between T2 and control group with highest value in T2 group. The digestibility coefficients of DM, OM, CP, EE and NDF differ significantly amongst the groups with highest values observed in group T2 followed by T1 and control. However, digestibility coefficient of CF differ significantly between control and other groups (T1 and T2), which were statistically at par with each other. However, the digestibility coefficient values of NFE differed significantly between T2 group and other groups that showed statistically non-significant. The DCP and TDN values differed significantly with positive balances of all nutrients amongst all treatment groups. Results revealed that mulberry leaves can replace up to 80% of concentrate mixture in corriedale lambs especially in CFB forms with positive effect on nutrient intake, digestibility and balances

Infrared surface plasmons on heavily doped silicon

Conductors with infrared plasma frequencies are potentially useful hosts of surface plasmon polaritons (SPP) with sub-wavelength mode confinement for sensing applications. A challenge is to identify such a conductor that also has sharp SPP excitation resonances and the capability to be functionalized for biosensor applications. In this paper we present experimental and theoretical investigations of IR SPPs on doped silicon and their excitation resonances on doped-silicon gratings. The measured complex permittivity spectra for p-type silicon with carrier concentration 6 x 10(19) and 1 x 10(20) cm(-3) show that these materials should support SPPs beyond 11 and 6 mu m wavelengths, respectively. The permittivity spectra were used to calculate SPP mode heights above the silicon surface and SPP propagation lengths. Reasonable merit criteria applied to these quantities suggest that only the heaviest doped material has sensor potential, and then mainly within the wavelength range 6 to 10 mu m. Photon-to-plasmon coupling resonances, a necessary condition for sensing, were demonstrated near 10 mu m wavelength for this material. The shape and position of these resonances agree well with simple analytic calculations based on the theory of Hessel and Oliner (1965)