Phase transitions in the Shastry-Sutherland lattice

Two recently developed theoretical approaches are applied to the Shastry-Sutherland lattice, varying the ratio $J'/J$ between the couplings on the square lattice and on the oblique bonds. A self-consistent perturbation, starting from either Ising or plaquette bond singlets, supports the existence of an intermediate phase between the dimer phase and the Ising phase. This existence is confirmed by the results of a renormalized excitonic method. This method, which satisfactorily reproduces the singlet triplet gap in the dimer phase, confirms the existence of a gapped phase in the interval $0.66<J'/J<0.86$Comment: Submited for publication in Phys. Rev.

Distorsi Sambungan Baut Akibat Curling Dan Pencegahannya Studi Kasus Sambungan Pelat Tipe Geser (Lap-joint) Dengan Baut Tunggal

. The phenomena of curling seldom happened on failure behavior of hot-rolled steel plate bolts connection, but relatively common found on the failure of cold-formed bolts connection (Cornell 1954; Roger-Hancock 2000; AISI 2001; Wallace et.al 2001), that relatively thin. So, it is interesting to find the curling phenomena on single bolts connection experiment (Dewobroto, 2009) that consist of hot-rolled steel plate. Also the final failure mechanism is different from the common mechanism of failure of bolts steel connection (Vinnakota, 2006), so it is to be questionable. Issues that are going to viewed are: (1) What caused curling to occur; (2) Was the same cause result distortion on the connection; (3) What are the strategies to overcome it. This paper will report the result of numerical simulation that suppose to resolve the question, also explains the benefit of using minimum bolt requirement, in a certain configuration on lap joint that can effectively avoid the distortion of the connection due to influence of curling

Kepak Nilai Kesejarahan Bagi Generasi Milenial Melalui Media Sosial Guna Membangun Revolusi Mental Ditengah Pandemi Global

This Study aims to determined the historical value for millennials through social media. This study uses historical resarch methods with several steps such as Heuristics, Criticism, Interpretation and Historiography. In this study, it countains historical value that must be understoot by the millennial generation at this time, especially with the efficiencyof using social media such as Instagram, Tiktok, Youtube, etc

Survei Penggerek Batang Jagung dan Kompleks Musuh Alaminya di Provinsi Gorontalo

Corn borer is one of the important pests on corn plant in Gorontalo Province, especially in three districts which are the center of maize planting development. Corn borer and its natural enemy complex in Gorontalo Province has not been clearly studied. The purpose of this study is to determine the complexity of the natural enemies of maize stem borer by calculating the diversity and composition. The survey method was used, in which the older larvae, pupae, and corn borer natural enemies were collected from the field in the three districts (Gorontalo, Boalemo, and Pohuwato). Observation plots in each district area of 2,500 m2, were divided into 3 sub plots with the size of 3×3 m, each plot is consisted of 45 plants at the spacing of 75×25 cm. The data were analysed descriptively and organized into tables. Shannon Index was used to count the diversity and composition of the pests and their natural enemies. The results showed that the corn borer species was Ostrinia furnacalis, while the dominant natural enemy was the tachinid fly. The analysis of Shannon diversity index for natural enemies of three districts of Gorontalo, Boalemo, and Pohuwato were 0.63, 0.61, and 0.97 respectively. Penggerek batang jagung adalah salah satu hama penting pada tanaman jagung di Provinsi Gorontalo terutama di tiga kabupaten sentra pengembangan jagung. Hama penggerek batang jagung dan kompleks musuh alaminya di Provinsi Gorontalo belum banyak dikaji. Tujuan kajian ini adalah melihat kompleksitas musuh alami penggerek batang jagung dengan menghitung keragaman dan komposisi. Metode yang digunakan adalah survei, yaitu mengumpulkan larva instar akhir, pupa penggerek batang jagung dan musuh alaminya dari lapangan di tiga kabupaten (Gorontalo, Boalemo, dan Pohuwato). Petak pengamatan di setiap kabupaten seluas 2.500 m2 yang dibagi dalam 3 sub plot berukuran 3×3 m. Jumlah tanaman jagung per plot sekitar 45 tanaman dengan jarak tanam 75×25 cm. Data dianalisis secara deskriptif dan disusun dalam tabel, untuk keragaman dan komposisi menggunakan Indeks Shannon. Hasil kajian menunjukkan bahwa jenis penggerek batang jagung adalah Ostrinia furnacalis, musuh alami didominasi Ordo Diptera Famili Tachinidae. Analisis Indeks Shannon keragaman musuh alami untuk Kabupaten Gorontalo, Kabupaten Boalemo, dan Kabupaten Pohuwato berturut-turut sebesar 0,63; 0,61; dan 0,97

A self-consistent perturbative evaluation of ground state energies: application to cohesive energies of spin lattices

The work presents a simple formalism which proposes an estimate of the ground state energy from a single reference function. It is based on a perturbative expansion but leads to non linear coupled equations. It can be viewed as well as a modified coupled cluster formulation. Applied to a series of spin lattices governed by model Hamiltonians the method leads to simple analytic solutions. The so-calculated cohesive energies are surprisingly accurate. Two examples illustrate its applicability to locate phase transition.Comment: Accepted by Phys. Rev.

The Effect of Intermittent Hypobaric Hypoxia on Oxidative Stress Status and Antioxidant Enzymes Activity in Rat Brain

Background: High altitude can cause hypobaric hypoxia (HH), resulted from the lower barometric pressure and hence partial pressure of oxygen. Hypoxia can lead to a lot of deleterious molecular and cellular changes, such as generation of free radicals or reactive oxygen species (ROS). Increasing of ROS can cause oxidative stress if the antioxidant enzyme does not increase simultaneously. Oxidative damage in brain has toxic effect on cognitive functions.Objective: In this study, we investigate effect of acute intermittent HH on oxidative stress and antioxidant enzyme activity in rat brain.Method: Wistar rats divided into 5 groups, consisting control group and four experimental groups which treated to HH. Rats were exposed to simulated HH equivalent to 35.000 feet in hypobaric chamber for 1 minute, repeated once a week.Results: Level of malondialdehyde and carbonyl in rat brain under acute HH increased at HH exposure (group I) compare to control group. These levels decreased afterward at intermittent HH exposure (group II-IV). Specific activity of superoxide dismutase (SOD) shows increasing level at intermittent HH exposure, especially group IV was increasing of SOD level significantly. The increasing pattern of specific activity of catalase was inversely from SOD pattern, but it still has higher activity in intermittent HH compare to control group.Conclusion: Brain tissue seems to be able to perform an adequate adaptive response to hypobaric hypoxia after the training, shown by its significantly decreased MDA and carbonyl level and also increased specific activity of SOD and catalase

Asthma remodeling: The pathogenic role of matrix metalloproteinase-9

AbstractBackgroundAsthma is an airway inflammatory disease with functional and structural changes, leading to bronchial hyperresponsiveness and airflow obstruction. Pathological repair of the airways leads to these structural changes referred as airway remodeling. Matrix metalloproteinases (MMPs) are extracellular degrading enzymes that play a critical role in the remodeling process.Aim of the studyIs to study matrix metalloproteinase-9 in asthmatic patients, detecting its pathogenic role in airway remodeling.Subjects and methodsSamples of broncho-alveolar lavage (BAL) fluid and bronchoscopic biopsies from 30 asthmatic patients (10 mild, 10 moderate and 10 severe) and 10 healthy volunteers were assessed for the levels of matrix metalloproteinase-9 (MMP-9) total and differential cell count (in BAL fluid), histological airway remodeling changes and immunohistochemical expression of MMP-9 (in mucosal biopsies).ResultsBAL and tissue MMP-9 (going hand in hand with airway remodeling changes) were higher in asthmatic patients and it was significantly increased with increased severity. BAL total cell count is higher in asthmatic patients. BAL eosinophils, neutrophils, lymphocytes as well as MMP-9 positive cell count were higher in asthmatic patients and increased with severity. MMP-9 tissue expression was also strongly inversely correlated with the spirometric parameters in asthmatic patients.ConclusionsMMP-9 plays a role in airway inflammation and airway remodeling in asthma. MMP-9 is an important player in airway remodeling in bronchial asthma and may be the link between inflammation and remodeling processes

Experimental Investigation on the Effect of Web Opening Dimension on the Behavior of R/C Hybrid Deep T-Beam Subjected to Pure Torsion

. An experimental study was conducted to investigate the effect of web opening dimension on the behavior of reinforced concrete hybrid deep T-beam subjected to pure torsion. Four reinforced concrete hybrid deep T-beams were tested under pure torsion, where the three beams with different dimension of circular web opening and the other beam without opening as a reference beam. The testing program and experimental results are presented. The results show that dimension of circular web opening with diameter more than 100 mm significantly reduces the cracking and ultimate torque. It is also shown that the angle of crack inclination with respect to the longitudinal axis of the beam increases with the increase of web opening dimension

Effect of Hypobaric Hypoxia Induction on Cognitive Function and Glutamate Receptor in Sprague-Dawley Rats

Induction of sublethal hypoxia provides neuroprotective effect pathological processes such as myocardial infarc and stroke. This study aimed to know the effect of intermittent hypobaric hypoxia (IHH) induction on cognitive function and glutamate receptor in the rat brain. The study was conducted at dr. Saryanto Institute for Aviation and Aerospace Health (LAKESPRA) from 2015-2016. 25 sprague dawley rats, divided into 4 IHH treatment groups and 1 control group. Group 1 was induced with 1x IHH exposure, group 2 was induced with 2x IHH exposure, group 3 was induced with 3x IHH exposure and group 4 was induced with 4x IHH exposure (days 1, 8, 15 and 22). After induction, cognitive function tests are performed with Y Maze and immunohistochemistry is performed to evaluate the glutamate receptor N-methyl-D-aspartic acid (NMDA). There were no significant differences between the four treatment groups compared with the control group (p&gt;0.05) on cognitif function, but significant difference in NMDA receptor. In conclution, HHI induction was not cause change cognitive fuction but increased the response of neuroplasticity of sprague-dawley rats brain tissue which assessed from increasing NMDA receptor.&nbsp