Critical Crossover Between Yosida-Kondo Dominant Regime and Magnetic Frustration Dominant Regime in the System of a Magnetic Trimer on a Metal Surface

Quantum Monte Carlo simulations were carried out for the system of a magnetic trimer on a metal surface. The magnetic trimer is arranged in two geometric configurations, viz., isosceles and equilateral triangles. The calculated spectral density and magnetic susceptibility show the existence of two phases: Yosida-Kondo dominant phase and magnetic frustration dominant phase. Furthermore, a critical transition between these two phases can be induced by changing the configuration of the magnetic trimers from isosceles to equilateral triangle.Comment: 8 pages, 4 figures; accepted for publication in J. Phys. Soc. Jp

Nanoscale quantum dot infrared sensors with photonic crystal cavity

We report high performance infrared sensors that are based on intersubband transitions in nanoscale self-assembled quantum dots combined with a microcavity resonator made with a high-index-contrast two-dimensional photonic crystal. The addition of the photonic crystal cavity increases the photocurrent, conversion efficiency, and the signal to noise ratio (represented by the specific detectivity D*) by more than an order of magnitude. The conversion efficiency of the detector at Vb=–2.6 V increased from 7.5% for the control sample to 95% in the PhC detector. In principle, these photonic crystal resonators are technology agnostic and can be directly integrated into the manufacturing of present day infrared sensors using existing lithographic tools in the fabrication facility

Dynamic hip screw technique in the management of trochanteric fracture

Background: Study was conducted to find the results of dynamic hip screw in the management of trochanteric fracture by analyzing the factors which influence post-operative mobility.Methods: Study was conducted in the department of orthopedics, GSL Medical College. Individuals >18 years, both genders who were diagnosed having trochanteric type I and II Boyd and Griffin stable fractures were included in the study. All surgeries were performed under spinal anesthesia, internal fixation with dynamic hip screw and 135o angled blade plate. Injectable third generation cephalosporins were used 24 hours preoperatively, intra- operatively and 5 days post-operatively, and oral antibiotics till suture removal. Patients allowed to sit on bed on 2nd and 3rd day and static quadriceps exercises were started from 2nd day onwards, hip and knee flexion exercises from 6 or 7th day and weight bearing walking form 10th day.Results: The average age was of the participants was 61.53 years, ranged between 41 to 80 years; 65% were female participants and 35% were male patients. In the study, 20 (50%) patients had right side fracture and left sided affection of trochanteric fracture to the remaining 50%. Most of the patients (67.5%) in this study were classified as type II Boyd and Griffin criteria, and 32.5% were type I. The clinical and functional outcome was calculated using the Kyle's criteria; 25% (10) showed excellent response, followed by good (50%), fair (15%) and poor (10%) results.Conclusions: Dynamic hip screw is the operative treatment of choice for stable trochanteric fractures. However, studies on large sample for long time are recommended

Spherical Shells of Classical Gauge Field and their Topological Charge as a Perturbative Expansion

We consider the classical equations of motion of $SU(2)$ gauge theory, without a Higgs field, in Minkowski space. We work in the spherical ansatz and develop a perturbative expansion in the coupling constant $g$ for solutions which in the far past look like freely propagating spherical shells. The topological charge $Q$ of these solutions is typically non-integer. We then show that $Q$ can be expressed as a power series expansion in $g$ which can be nonzero at finite order. We give an explicit analytic calculation of the order $g^5$ contribution to $Q$ for specific initial pulses. We discuss the relation between our findings and anomalous fermion number violation, and speculate on the physical implications of our results.Comment: 18 pages in REVTE

Exactly solvable toy models of unconventional magnetic alloys: Bethe Ansatz versus Renormalization Group method

We propose toy models of unconventional magnetic alloys, in which the density of band states, $\rho(\epsilon)$, and hybridization, $t(\epsilon)$, are energy dependent; it is assumed, however, that $t^2(\epsilon)\propto\rho^{-1}(\epsilon)$, and hence an effective electron-impurity coupling $\Gamma(\epsilon)=\rho(\epsilon)t^2(\epsilon)$ is energy independent. In the renormalization group approach, the physics of the system is assumed to be governed by $\Gamma(\epsilon)$ only rather than by separate forms of $\rho(\epsilon)$ and $t(\epsilon)$. However, an exact Bethe Ansatz solution of the toy Anderson model demonstrates a crucial role of a form of inverse band dispersion $k(\epsilon)$.Comment: A final version. A previous one has been sent to Archive because of my technical mistake. Sorr

Assessment of crop loss in Arabica coffee due to white stem borer, Xylotrechus quadripes Chevrolat (Coleoptera: Cerambycidae) infestation

The coffee white stem borer (CWSB) is the most dreaded pest of Arabica coffee in India. Due to the concealed nature of this pest, the management measures are difficult and require the timely implementation of control measures. The recommended practices for the management of CWSB mainly targets on eggs and early instar larvae, apart from tracing and uprooting of infested plants before the commencement of flight periods (April-May and Oct-Dec). In general, youngArabica coffee plants infested by CWSB die within a year, whereas aged plants withstand the attack for few more years. However, such plants become less productive, susceptible to diseases and also serve as inoculum for further spreading of the infestation. A study was undertaken to assess the crop loss due to CWSB infestation on established Arabica plantation in Tamil Nadu. The result indicated a significant difference between healthy and infested plants and the crop loss was to the tune of 17.7 per cent. Further, quantitative data on out-turn percentages recorded at different stages of coffee processing (right from harvesting of fruits to marketable green coffee bean) are discussed in this paper

Synthesis of β-amino alcohols by ring opening of epoxides with amines catalyzed by sulfated tin oxide under mild and solvent-free conditions

One significant and elegant method for creating β-amino alcohols, which are useful intermediates for the synthesis of many different natural and synthetic pharmaceutical compounds, is to open the rings of epoxides with amines. When sulfated tin oxide catalyst (2 mol%) is present, epoxides can open their rings and react with amines to produce corresponding β-amino alcohols in good to high yields under mild circumstances. Under clean circumstances and in a short amount of time, the reaction demonstrated high regioselectivity and functioned well with both aromatic and aliphatic amines at room temperature

The numerical renormalization group method for quantum impurity systems

In the beginning of the 1970's, Wilson developed the concept of a fully non-perturbative renormalization group transformation. Applied to the Kondo problem, this numerical renormalization group method (NRG) gave for the first time the full crossover from the high-temperature phase of a free spin to the low-temperature phase of a completely screened spin. The NRG has been later generalized to a variety of quantum impurity problems. The purpose of this review is to give a brief introduction to the NRG method including some guidelines of how to calculate physical quantities, and to survey the development of the NRG method and its various applications over the last 30 years. These applications include variants of the original Kondo problem such as the non-Fermi liquid behavior in the two-channel Kondo model, dissipative quantum systems such as the spin-boson model, and lattice systems in the framework of the dynamical mean field theory.Comment: 55 pages, 27 figures, submitted to Rev. Mod. Phy

Room Temperature Kondo effect in atom-surface scattering: dynamical 1/N approach

The Kondo effect may be observable in some atom-surface scattering experiments, in particular, those involving alkaline-earth atoms. By combining Keldysh techniques with the NCA approximation to solve the time-dependent Newns-Anderson Hamiltonian in the infinite-U limit, Shao, Nordlander and Langreth found an anomalously strong surface-temperature dependence of the outgoing charge state fractions. Here we employ the dynamical 1/N expansion with finite Coulomb interaction U to provide a more realistic description of the scattering process. We test the accuracy of the 1/N expansion in the spinless N = 1 case against the exact independent-particle solution. We then compare results obtained in the infinite-U limit with the NCA approximation and recover qualitative features found previously. Finally, we analyze the realistic situation of Ca atoms with U = 5.8 eV scattered off Cu(001) surfaces. Although the presence of the doubly-ionized Ca species can change the absolute scattered positive Ca yields, the temperature dependence is qualitatively the same as that found in the infinite-U limit. One of the main difficulties that experimentalists face in attempting to detect this effect is that the atomic velocity must be kept small enough to reduce possible kinematic smearing of the metal's Fermi surface.Comment: 15 pages, 10 Postscript figures; references and typos correcte