Brownian Motion and Quantum Dynamics of Magnetic Monopoles in Spin Ice

Spin ice illustrates many unusual magnetic properties, including zero point entropy, emergent monopoles and a quasi liquid-gas transition. To reveal the quantum spin dynamics that underpin these phenomena is an experimental challenge. Here we show how crucial information is contained in the frequency dependence of the magnetic susceptibility and in its high frequency or adiabatic limit. These measures indicate that monopole diffusion is strictly Brownian but is underpinned by spin tunnelling and is influenced by collective monopole interactions. We also find evidence of driven monopole plasma oscillations in weak applied field, and unconventional critical behaviour in strong applied field. Our results resolve contradictions in the present understanding of spin ice, reveal unexpected physics and establish adiabatic susceptibility as a revealing characteristic of exotic spin systems.Comment: Main : 12 pages, 6 figures. Supplementary Information : 10 pages, 7 figures. Manuscript submitte

Magnetic spectrum of the two-dimensional antiferromagnet La2CoO4 studied by inelastic neutron scattering

We report measurements of the magnetic excitation spectrum of the layered antiferromagnet La2CoO4 by time-of-flight neutron inelastic scattering. In the energy range probed in our experiments (0-250 meV) the magnetic spectrum consists of spin-wave modes with strong in-plane dispersion extending up to 60 meV, and a nearly dispersionless peak at 190 meV. The spin-wave modes exhibit a small (~1 meV) dispersion along the magnetic zone boundary. We show that the magnetic spectrum can be described very well by a model of a Heisenberg antiferromagnet that includes the full spin and orbital degrees of freedom of Co2+ in an axially-distorted crystal field. The collective magnetic dynamics are found to be controlled by dominant nearest-neighbour exchange interactions, strong XY-like single-ion anisotropy and a substantial unquenched orbital angular momentum.Comment: 8 pages, 7 figure

Structural efficiency studies of corrugated compression panels with curved caps and beaded webs

Curved cross-sectional elements are employed in structural concepts for minimum-mass compression panels. Corrugated panel concepts with curved caps and beaded webs are optimized by using a nonlinear mathematical programming procedure and a rigorous buckling analysis. These panel geometries are shown to have superior structural efficiencies compared with known concepts published in the literature. Fabrication of these efficient corrugation concepts became possible by advances made in the art of superplastically forming of metals. Results of the mass optimization studies of the concepts are presented as structural efficiency charts for axial compression

Thermodynamic and magnetic properties of the layered triangular magnet NaNiO2

We report muon-spin rotation, heat capacity, magnetization, and ac magnetic susceptibility measurements of the layered spin-1/2 antiferromagnet NaNiO2. These show the onset of long-range magnetic order below T_N = 19.5K. Rapid muon depolarization persisting to about 5K above T_N is consistent with the presence of short-range magnetic order. The temperature and frequency dependence of the ac susceptibility suggests that magnetic clusters persist above 25K in the paramagnetic state and that their volume fraction decreases with increasing temperature. A frequency dependent peak in the ac magnetic susceptibility at T_sf = 3K is observed, consistent with a slowing of spin fluctuations at this temperature. A partial magnetic phase diagram is deduced.Comment: 4 pages, 4 figure

Understanding the challenges of immersive technology use in the architecture and construction industry: A systematic review

Despite the increasing scholarly attention being given to immersive technology applications in the architecture and construction industry, very few studies have explored the key challenges associated with their usage, with no aggregation of findings or knowledge. To bridge this gap and gain a better understanding of the state-of-the-art immersive technology application in the architecture and construction sector, this study reviews and synthesises the existing research evidence through a systematic review. Based on rigorous inclusion and exclusion criteria, 51 eligible articles published between 2010 and 2019 (inclusive) were selected for the final review. Predicted upon a wide range of scholarly journals, this study develops a generic taxonomy consisting of various dimensions. The results revealed nine (9) critical challenges which were further ranked in the following order: Infrastructure; Algorithm Development; Interoperability; General Health and Safety; Virtual Content Modelling; Cost; Skills Availability; Multi-Sensory Limitations; and Ethical Issues

Entrepreneurs - Turns Massive Challenges (Covid 19) In To Meaningful Change

An entrepreneur is a person who undertakes risk to make profit from an opportunity, than working as an ordinary employee. As we are experiencing the worldwide COVID-19 pandemic, Entrepreneurs have to face a new challenge: that it is not only a huge sanitary and health crisis affecting people in all over the world. Though the world is changing rapidly in to the different scenario and reality are not the same depending on where you are running your business today. This is also an unprecedented downturn on the global economy. This paper presents how an Entrepreneur turns massive complexity into meaningful change. Entrepreneurs must initiate the financial and operational challenges of COVID - 19 while rapidly addressing the needs of their people, customers and suppliers

Spin gaps and magnetic structure of NaxCoO2

We present two experiments that provide information on spin anisotropy and the magnetic structure of NaxCoO2. First, we report low-energy neutron inelastic scattering measurements of the zone-center magnetic excitations in the magnetically ordered phase of Na0.75CoO2. The energy spectra suggest the existence of two gaps, and are very well fitted by a spin-wave model with both in-plane and out-of-plane anisotropy terms. The gap energies decrease with increasing temperature and both gaps are found to have closed when the temperature exceeds the magnetic ordering temperature T_m~22 K. Secondly, we present neutron diffraction studies of Na0.85CoO2 with a magnetic field applied approximately parallel to the c axis. For fields in excess of ~8T a magnetic Bragg peak was observed at the (0,0,3) position in reciprocal space. We interpret this as a spin-flop transition of the A-type antiferromagnetic structure, and we show that the spin-flop field is consistent with the size of the anisotropy gap.Comment: 9 pages, 7 figure

A study of femoral bicondylar angle in Udaipur, India zone

Background: Human body consists of 206 bones; among which femur. The thigh bone is considered as the biggest and strongest bone of the body. The bone contains a femoral bicondylar angle which helps in maintaining the balance and certain movements of the body. Those movements are essential to stand upright and erect; therefore, helps in balancing the posture of the body. Bicondylar angle shows various gestures and characteristics essential for describing the necessary ailments of the human skeleton. Thus, the present study is designed with an aim to measure and compare the bicondylar angle of femur both in males and females in Udaipur, Rajasthan, India zone.Methods: Totally, 96 bones were studied- 48 males and 48 females’ bones in 2 years duration. The study was carried out in the Department of Anatomy of Geetanjali Medical College and Hospital and R.N.T. Medical College. The bicondylar angle was measured with a suitable apparatus comprising of compass, Digital Vernier Calliper, scale and protector (Figure 1) along with osteometric board. Bicondylar angle of male and female bone was calculated using SPSS software.Results: The study shows that the bicondylar angle of left femur was greater than right femur in both the genders, but their side differences was statistically insignificant (p>0.05).Conclusions: Hence, the bicondylar angle of female is larger than in comparison to males and these results can put emphasis/light on the orthopaedic clinicians and surgeons to know the etiology of osteometric diseases

Quality Improvement in Higher Education Through Normalization of Student Feedback Data Using Evolutionary Algorithm

Student Feedback is a vital information that helps not only to evaluate the existing academic practices but also to rectify the discrepancies if any, enabling continuous quality improvement. Often the educational institutions make decisions on the teaching and delivery strategies and requirements of the students based on the students’ Feedback. Due to various factors like the composition of the class in terms of student background, personal relationship with the teacher and other factors, the Feedback generally remains so scattered that at times it may not be possible to arrive at a conclusion based on the feedback. Any decision, based on this already obscure feedback, can only be flawed. This underscores the necessity of normalizing the Feedback data so that one can elicit a clear numerical value for each item in questionnaire rather than quantifying the same in terms of number of responses ‘for’ and ‘against’ the item. Employing an artificial intelligence method, this paper aims at developing an efficient scheme for the analysis of students’ Feedback taking into account the above mentioned factors. Because of its ease of use, the proposed feedback evaluation mechanism can be used on monthly basis in a given academic year, thus achieving continuous improvement of quality. It is hoped that this can serve as an effective tool in improving the learning and teaching methods, standards of education and ultimately the quality of higher education