Dynamic elastic properties and magnetic susceptibility across the austenite-martensite transformation in site-disordered ferromagnetic Ni-Fe-Al alloy

Besides permitting an accurate determination of the ferromagnetic-to-paramagnetic phase transition temperature and the characteristic temperatures for the beginning and end of the growth of martensite (austenite) phase at the expense of austenite (martensite) phase while cooling (heating), the results of an extensive ac susceptibility, sound velocity and internal friction investigation of the thermoelastic martensitic transformation in melt-quenched (site-disordered) Ni55Fe20Al25 alloy provide a clear experimental evidence for the following. Irreversible thermoelastic changes (thermal hysteresis) occur in the austenite phase in the premartensitic regime. In the heating cycle, the system retains the "memory" of the initiation and subsequent growth of the martensitic phase (at the expense of the parent austenite phase) that had taken place during the cooling cycle in the austenite-martensite phase coexistence region. We report and discuss these novel findings in this communication.Comment: 5 figure

Is gadolinium a helical antiferromagnet or a collinear ferromagnet?

Controversial issues concerning the nature of magnetic ordering in gadolinium are briefly reviewed. The recent experimental results are shown to resolve most of such issues in that they rule out the possibility of a helical spin structure in Gd and clearly bring out the role of longrange dipolar interactions in stabilising collinear ferromagnetic order for temperatures between the spin-reorientation temperature and the Curie point

Two-dimensional frustrated spin systems in high magnetic fields

We discuss our numerical results on the properties of the S = 1/2 frustrated J1-J2 Heisenberg model on a square lattice as a function of temperature and frustration angle phi = atan(J2/J1) in an applied magnetic field. We cover the full phase diagram of the model in the range -pi <= phi <= pi. The discussion includes the parameter dependence of the saturation field itself, and addresses the instabilities associated with it. We also discuss the magnetocaloric effect of the model and show how it can be used to uniquely determine the effective interaction constants of the compounds which were investigated experimentally.Comment: 4 pages, 5 figures, proceedings of RHMF 200

Proceedings of Bhutan: Biodemocracy & Resilience Conference 2020

The Second Bhutan Biodemocracy and Resilience Conference With a focus on pathways to resilience in the face of cross-sectoral and regional effects of the coronavirus pandemic)(held on December 21-22, 2020) brought together a range of people from politics, civil society, media, business, academia, education, industry, agriculture in multiple panels to discuss the key developmental challenges in the context of the pandemic. The conference was covered in the Bhutanese media and received an overwhelmingly positive feedback from various sectors of society and on social media. The aim of the project was to bring together key stakeholders in Bhutan to produce engaged deliberations and reports that can guide policymaking. The two-day conference had panel discussions on the effects of the coronavirus crisis in relation to economic vulnerability and climate change, volunteerism and public health, local governments, agriculture, employment, hydropower and tourism. A keynote address from Lyonpo Ugyen Dorji, Minister of Labour and Human Resources of the Royal Government of Bhutan, began the two days of panel discussions on the pandemic, public policy and development. The talks were livestreamed and watched by thousands of people and were covered nationally. The BBR 2020 conference built upon the first conference titled ‘Bhutan as Biodemocracy: Building Socioeconomic and Environmental Resilience’ which was held in July 2019

Logarithmic correction to the Bekenstein-Hawking entropy of the BTZ black hole

We derive an exact expression for the partition function of the Euclidean BTZ black hole. Using this, we show that for a black hole with large horizon area, the correction to the Bekenstein-Hawking entropy is $-3/2 log(Area)$, in agreement with that for the Schwarzschild black hole obtained in the canonical gravity formalism and also in a Lorentzian computation of BTZ black hole entropy. We find that the right expression for the logarithmic correction in the context of the BTZ black hole comes from the modular invariance associated with the toral boundary of the black hole.Comment: LaTeX, 10 pages, typos corrected, clarifications adde

Eurasia spreading basin to Laptev Shelf transition: structural pattern and heat flow

New geophysical data have become available from shipborne and satellite measurements allowing a re-evaluation of the largely unknown junction of the Arctic spreading centre and the northeastern Siberian continental margin where the transpolar mid-ocean Gakkel Ridge abuts against the continental slope of the Laptev Sea. Based on multichannel seismic reflection and gravity data, this sediment-covered spreading axis can be traced to the continental rise where it is cut-off by a transcurrent fault. Further continuation of the extensional axis into the continental slope can be attributed to two asymmetric grabens, which terminate against the prominent Khatanga–Lomonosov Fracture. Remnants of hydrothermal fauna and high heat-flow values of approximately 100 mW m−2 documented around these grabens in the up-slope area are typical for an oceanic spreading axis. Thus we consider these grabens to be morphotectonic termination of the global Atlantic–Arctic spreading system with plate motions shifting to the Khatanga–Lomonosov Fracture. The high heat flow and the distribution of earthquake epicentres allow us to assume that the present-day divergent plate tectonic boundary passes from the Gakkel Ridge to the eastern part of Laptev Sea with an offset of initial rifting along the Bel'kov–Svyatoi Nos Rift to the projected prolongation of the buried spreading axis by 140–150 km

A rare constellation of multiple upper limb anomalies

We describe an unusual combination of unilateral upper limb variations, including an axillary arch, absence of a &#8220;typical&#8221; musculocutaneous nerve, direct lateral cord innervation of the muscles usually supplied by the musculocutaneous nerve, variant superficial brachial artery, a high anomalous origin of the common interosseous artery and a superficial ulnar artery noted during routine cadaver dissection. The embryological basis, recent molecular insights concerning such a constellation of anomalies and its clinical relevance are discussed