മത്തി എന്ന മത്സ്യ സമസ്യ

മത്തി എന്ന മത്സ്യ സമസ്

Photodisintegration of aligned deuterons at astrophysical energies using linearly polarized photons

Following the model independent approach to deuteron photodisintegration with linearly polarized $\gamma-$rays, we show that the measurements of the tensor analyzing powers on aligned deuterons along with the differential cross section involve five different linear combinations of the isovector $E1^j_v; j=0,1,2$ amplitudes interfering with the isoscalar $M1_s$ and $E2_s$ amplitudes. This is of current interest in view of the recent experimental finding \cite{blackston1} that the three $E1^j_v$ amplitudes are distinct and also the reported experimental observation \cite{sawatzky} on the front-back (polar angle) asymmetry in the differential cross section.Comment: 12 page

Coherent quantum beats: spectroscopy of energy differences buried within inhomogeneous broadening

Precision spectroscopy of solid-state systems is challenging due to inhomogeneous broadening. We describe a technique -- coherent quantum beats -- that enables the measurement of small frequency shifts within an inhomogeneously broadened distribution, while addressing the full ensemble. We show that the technique can be used to obtain improvements in signal size and spectral resolution, offering advantages for precision measurements in solids.Comment: 5 pages, 7 figure

Marine Fisheries Policy Brief-1 സമുദ്ര മത്സ്യമേഖലാ നയ പരിപ്രേക്‌ഷ്യം - 1 കേരളം (Marine Fisheries Policy Brief-1 Kerala Malayalam version)

Marine Fisheries Policy Brief-1 സമുദ്ര മത്സ്യമേഖലാ നയ പരിപ്രേക്‌ഷ്യം - 1 കേരളം (Marine Fisheries Policy Brief-1 Kerala Malayalam version

Marine Fisheries Policy Brief-1 Kerala

Kerala which has a coastline of 590 km ranks first in marine fish production of India, contributing nearly 25% (5.81 lakh tonnes on average) to the total annual production. The export of marine products from the State earns valuable foreign exchange besides affording innumerable job opportunities in the industry. The population depending on fisheries has steadily increased over the years and stood at 6,02,234 in 2005 (Anon., 2005). Kerala has been in the forefront of absorbing innovative and new technologies in fishing practices, which have led the marine fisheries sector to take a complex structure. The 1980s was an important period in the development of marine fisheries in Kerala. In the first half of the period the motorized sector grew rapidly and became the most important sector yielding the maximum catch in 1988. By that time, ringseine became very popular in exploiting the pelagic resources and replaced the boatseines to a very great extent. Huge size of the new net (450 to 1000 m long) and large number of crew (30 to 50) needed for its operation necessitated larger boats with high capacity outboard engines (3 outboard engines of 40 hp each). This facilitated extension of fishing grounds for the motorized sector. The fishing grounds covered by the mechanised sector also extended by increasing the boat size and fishing effort and efficiency through multi-day fishing during the late 90s

Marine Fisheries Policy Brief-2; Seasonal Fishing Ban

Fishery resources need to be monitored and managed to maintain harvest at sustainable levels as they provide food and livelihood security to millions of population. Management of fisheries is not confined to management of stocks alone but it should consider all the stakeholders associated with the sector directly or indirectly such as fishers, traders, those involved in post-harvest operations and those who provide support services to the sector. Besides, fish stocks live in a highly variable and a complex ecosystem and are affected by human interventions and vagaries of nature, which emphasises the need for including the risk and uncertainty factors in the management strategie

Exploring Zeptosecond Quantum Equilibration Dynamics: From Deep-Inelastic to Fusion-Fission Outcomes in 58^{58}Ni+60^{60}Ni Reactions

Energy dissipative processes play a key role in how quantum many-body systems dynamically evolve towards equilibrium. In closed quantum systems, such processes are attributed to the transfer of energy from collective motion to single-particle degrees of freedom; however, the quantum many-body dynamics of this evolutionary process are poorly understood. To explore energy dissipative phenomena and equilibration dynamics in one such system, an experimental investigation of deep-inelastic and fusion-fission outcomes in the $^{58}$Ni+$^{60}$Ni reaction has been carried out. Experimental outcomes have been compared to theoretical predictions using Time Dependent Hartree Fock and Time Dependent Random Phase Approximation approaches, which respectively incorporate one-body energy dissipation and fluctuations. Excellent quantitative agreement has been found between experiment and calculations, indicating that microscopic models incorporating one-body dissipation and fluctuations provide a potential tool for exploring dissipation in low-energy heavy ion collisions.Comment: 11 pages, 9 figures, 1 table, including Supplemental Material - Version accepted for publication in Physical Review Letter

Upper Limits on the Continuum Emission from Geminga at 74 and 326 MHz

We report a search for radio continuum emission from the gamma-ray pulsar Geminga. We have used the VLA to image the location of the optical counterpart of Geminga at 74 and 326 MHz. We detect no radio counterpart. We derive upper limits to the pulse-averaged flux density of Geminga, taking diffractive scintillation into account. We find that diffractive scintillation is probably quenched at 74 MHz and does not influence our upper limit, S < 56 mJy (2\sigma), but that a 95% confidence level at 326 MHz is S < 5 mJy. Owing to uncertainties on the other low-frequency detections and the possibility of intrinsic variability or extrinsic variability (refractive interstellar scintillation) or both, our non-detections are nominally consistent with these previous detections.Comment: 8 pages, LaTeX2e with AASTeX 4.0, 3 figures; to be published in Ap

Spectral Function in Mott Insulating Surfaces

We show theoretically the fingerprints of short-range spiral magnetic correlations in the photoemission spectra of the Mott insulating ground states realized in the triangular silicon surfaces K/Si(111)-B and SiC(0001). The calculated spectra present low energy features of magnetic origin with a reduced dispersion ~10-40 meV compared with the center-of-mass spectra bandwidth ~0.2-0:3 eV. Remarkably, we find that the quasiparticle signal survives only around the magnetic Goldstone modes. Our findings would position these silicon surfaces as new candidates to investigate non-conventional quasiparticle excitations.Comment: 5 pages, 4 figures. To be published in Journal of Physics: Condensed Matte

Fixational Saccades and Their Relation to Fixation Instability in Strabismic Monkeys

Purpose: To evaluate the contribution of fixational saccades toward fixation instability in strabismic monkeys. Methods: Binocular eye movements were measured as six experimental monkeys (five strabismic monkeys and one monkey with downbeat nystagmus) and one normal monkey fixated targets of two shapes (Optotype, Disk) and two sizes (0.5°, 2°) during monocular and binocular viewing. Fixational saccades were detected using an unsupervised clustering algorithm. Results: When compared with the normal monkey, amplitude and frequency of fixational saccades in both the viewing and nonviewing eye were greater in 3 of 5 strabismic monkeys (1-way ANOVA on ranks P < 0.001; median amplitude in the normal monkey viewing eye: 0.33°; experimental animals: median amplitude range 0.20–0.82°; median frequency in the normal monkey: 1.35/s; experimental animals: median frequency range 1.3–3.7/s). Increase in frequency of fixational saccades was largely due to quick phases of ongoing nystagmus. Fixational saccade amplitude was increased significantly (3-way ANOVA; P < 0.001) but by small magnitude depending on target shape and size (mean difference between disk and optotype targets = 0.02°; mean difference between 2° and 0.5° targets = 0.1°). Relationship between saccade amplitude and the Bivariate Contour Ellipse Area (BCEA) was nonlinear, showing saturation of saccade amplitude. Fixation instability in depth was significantly greater in strabismic monkeys (vergence BCEA: 0.63 deg2–2.15 deg2) compared with the normal animal (vergence BCEA: 0.15 deg2; P < 0.001). Conclusions: Increased fixational instability in strabismic monkeys is only partially due to increased amplitude and more frequent fixational saccades. Target parameter effects on fixational saccades are similar to previous findings of target effects on BCEA