Electronic correlations in the Hubbard model on a bi-partite lattice

In this work we study the Hubbard model on a bi-partite lattice using the coupled-cluster method (CCM). We first investigate what, within this approach, allows us to reproduce the zero order parameter in the 1D model, as predicted by the exact solution. We show that we need a critical correlation in some of the coupled-cluster model coefficients to reproduce this result, as can be obtained by applying some very accurate results using the CCM for the Heisenberg model. Using the same approach we then tackle the 2D Hubbard model on a square and a honeycomb lattice, both of which can be thought to represent 2D materials. We also analyse the charge and spin excitations, with reasonable results.Comment: Major update to previous versio

A prospective comparative study in the management of Neer’s type II and type III proximal humerus fracture with proximal humerus nail versus proximal humerus internal locking system

Background: Proximal humerus fractures account for approximately 4-5 % of all the fractures and are next in occurrence to hip fractures and distal radius fractures in elderly population.Methods: A prospective study of 40 patients with Neer’s type II and type III proximal humerus fracture, among which 20 were treated with proximal humerus nail and 20 with proximal humerus internal locking system at two Hospitals attached to J.J.M Medical College Davangere, Karnataka, India between September 2015 to December 2016. At final follow up results were assessed with constant shoulder scoring system.Results: In the PHN group, 8 patients (40%) showed excellent outcome, 8 patients (40%) showed good outcome and 4 patients (20%) showed fair outcome. Among the PHILOS group, 12 patients (60%) showed good outcome, 6 patients (30%) showed fair outcome and 02 patients (10%) with poor outcome.Conclusions: Proximal humerus nail for Neer’s type II and type III proximal humerus fracture has better results compared to proximal humerus locking plate system with increased range of movements and restoring better shoulder biomechanics

Thermal performance of a solar assisted horizontal ground heat exchanger

This paper presents an experimental study of a solar assisted horizontal ground heat exchanger system (HGHEs) operating as a daily heat storage unit. Initially, several soils were assessed as sensible heat storage mediums, with sand and gravel selected as the most appropriate. Then, a HGHEs was designed and connected to a 15m2 test room with a heating load of 1kW at Nottingham Trent University. Heating cables, simulating solar input, were used to heat the soil in the HGHEs to 70℃, then a heat transfer fluid (HTF), was circulated through a closed loop heat exchanger to extract the stored heat. The parameters of soil backfill and HTF mass flow rate were investigated in the HGHEs. Several output flowrates ranging between 0.1 to 0.6L/min were tested, producing discharge times varying between a few hours to a few days. The HTF mass flowrate was found to be the most significant parameter, affecting the HGHEs thermal capacity and heat exchange rates. The sand filled HGHE produced approximately 50% more hot water (T>35℃) during a longer duration achieving an efficiency of 78% compared to the gravel filled HGHE with a lower system efficiency of 58%. Insulating the HGHE system was found to reduce heat losses and avoid temperature fluctuations in the HGHEs. Overall, the results show the hot water quantity, temperature range and duration produced from the system were in line with low temperature district heating guidelines and can be applied to some household heating applications incorporating low flows and low temperatures

AC-coupled GaAs microstrip detectors with a new type of integrated bias resistors

Full size single-sided GaAs microstrip detectors with integrated coupling capacitors and bias resistors have been fabricated on 3'' substrate wafers. PECVD deposited SiO_2 and SiO_2/Si_3N_4 layers were used to provide coupling capacitaces of 32.5 pF/cm and 61.6 pF/cm, respectively. The resistors are made of sputtered CERMET using simple lift of technique. The sheet resistivity of 78 kOhm/sq. and the thermal coefficient of resistance of less than 4x10^-3 / degree C satisfy the demands of small area biasing resistors, working on a wide temperature range.Comment: 20 pages, 9 figures, to be published in NIM

Prevalence of Gastro-intestinal Parasites of Cattle in Ogbomoso, Oyo State

A study was carried out on the prevalence of gastrointestinal (GI) nematodes infection in naturally infected cattle in Ogbomoso area of Oyo State using standard parasitological techniques. The results indicated that out of the 1000 cattle examined, 30(3%) were infected and parasites identified were Haemonchus contortus 8(26.7%), Trichostrongylus spp 13(43.3%) and Cooperia spp 2(6.7%) as single infection. Mixed infections involved Haemonchus contortus with Trichostrongylus spp 5(16.7%), H. contortus with Cooperia spp 2(6.7%) being statistically significant (p<0.05).The prevalence rates of GI nematodes based on the sex and age of the cattle were 3.02%, 2.97%, 3.2% and 2.8% in adult, young, male and female animals respectively, with the highest faecal egg counts in adult animals with no statistical significance difference (p>0.05). Both female and male cattle were more infected with Haemonchus contortus with 5 (62.5%) each, while only male and young cattle were infected with Cooperia spp 2 (100%) and 1 (50%) respectively. The highest rate of mixed infection occurred in adult cattle with Haemonchus contortus and Trichostrongylus spp 2 (100%) followed by Haemonchus contortus and Cooperia spp in male 4 (80%) and adult 3 (60%).The variation in the prevalence of GI nematodes among sex and age groups within systems can be used as an entry point towards rational use of anthelmintics for each management system. More studies on seasonal transmission pattern of all these parasites are required in order to design rational, economic and locally sustainable parasite control programmes.Key words: Prevalence, gastro-intestinal parasites, Cattle, Ogbomos

Inhibition of Gastric Acid Secretion by Unfractionated and Low Molecular Weight Heparins in the Rat

The majority of patients receiving heparin preparations are at stress, which is a risk factor for the development of gastric erosions. Our aim was to examine the effect of unfractionated heparin (UFH) and low molecular weight heparins (LMWHs) on gastric acid secretion. Gastric acid secretion was induced in urethane-anesthetized rats by distention of the stomach (2 ml saline for 2 h) in addition to histamine or bethanechol stimulation. Distension-stimulated acid secretion (2 ml for 2 h) was significantly inhibited by intraperitoneal administration of UFH (2000 IU/kg, 19% reduction), enoxaparin (180 or 360 IU/kg, 59.2 and 87.1%, reduction, respectively), nadroparin (1000 or 2000 IU/kg, 36 and 60.7% reduction, respectively), and tinzaparin (3000 IU/kg, 41.3% reduction). All tested heparins also suppressed acid secretion in response to distention and histamine or bethanechol stimulation. Pretreatment with indomethacin did not abolish the gastric inhibitory action of nadroparin. After truncal vagotomy or atropine, nadroparin failed to inhibit acid secretion stimulated by histamine. Ganglionic blockade with guanethidine abolished the gastric inhibitory action of nadroparin or UFH. It is concluded that both UFH and LMWHs administered peripherally inhibit stimulated gastric acid secretion in the rat. This effect of heparins is determined by cholinergic and partly by adrenergic mechanisms