On the Small Sample Properties of Dickey Fuller and Maximum Likelihood Unit Root Tests on Discrete-Sampled Short-Term Interest Rates

Testing for unit roots in short-term interest rates plays a key role in the empirical modelling of these series. It is widely assumed that the volatility of interest rates follows some time-varying function which is dependent of the level of the series. This may cause distortions in the performance of conventional tests for unit root nonstationarity since these are typically derived under the assumption of homoskedasticity. Given the relative unfamiliarity on the issue, we conducted an extensive Monte Carlo investigation in order to assess the performance of the DF unit root tests, and examined the effects on the limiting distributions of test procedures (t- and likelihood ratio tests) based on maximum likelihood estimation of models for short-term rates with a linear drift.Unit root, interest rates, CKLS model.

Disorder-specific functional abnormalities during sustained attention in youth with Attention Deficit Hyperactivity Disorder (ADHD) and with Autism

Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are often comorbid and share behavioural-cognitive abnormalities in sustained attention. A key question is whether this shared cognitive phenotype is based on common or different underlying pathophysiologies. To elucidate this question, we compared 20 boys with ADHD to 20 age and IQ matched ASD and 20 healthy boys using functional magnetic resonance imaging (fMRI) during a parametrically modulated vigilance task with a progressively increasing load of sustained attention. ADHD and ASD boys had significantly reduced activation relative to controls in bilateral striato–thalamic regions, left dorsolateral prefrontal cortex (DLPFC) and superior parietal cortex. Both groups also displayed significantly increased precuneus activation relative to controls. Precuneus was negatively correlated with the DLPFC activation, and progressively more deactivated with increasing attention load in controls, but not patients, suggesting problems with deactivation of a task-related default mode network in both disorders. However, left DLPFC underactivation was significantly more pronounced in ADHD relative to ASD boys, which furthermore was associated with sustained performance measures that were only impaired in ADHD patients. ASD boys, on the other hand, had disorder-specific enhanced cerebellar activation relative to both ADHD and control boys, presumably reflecting compensation. The findings show that ADHD and ASD boys have both shared and disorder-specific abnormalities in brain function during sustained attention. Shared deficits were in fronto–striato–parietal activation and default mode suppression. Differences were a more severe DLPFC dysfunction in ADHD and a disorder-specific fronto–striato–cerebellar dysregulation in ASD

DOES THE INTEGRATION OF ICT IN PHYSICS INSTRUCTION IN SECONDARY SCHOOLS PLAY THE MAGIC CARD?

Physics is one of the subjects that have suffered low enrolment and performance in secondary schools. This enrolment and performance are pegged to the students’ perception that Physics is difficult and uninteresting due to its abstract nature. Research has shown that integration of ICT in Physics instruction has the capability of simplifying the abstract content as well as creating interest in learners and consequently improving the quality of education. However, for this to be possible, Physics requires adequate operational ICT knowledge and resources. This study targeted 40 schools, 40 principals and 121 Physics teachers. The study was based on the Unified Theory of Acceptance and Use of Technology (UTAUT) model. Descriptive survey design was used. Random sampling technique was used to get a sample of 18 schools and 52 Physics teachers whereas purposive sampling was used to get 18 principals. Questionnaires, interview schedules and an observation schedule were used to collect data. Validity and reliability of the study instruments were established through consultation, triangulation and piloting. The data was analyzed using SPSS. The study found that integration of ICT in Physics instruction in secondary schools was still very low. The study recommends that more ICT resources should be provided to secondary schools; and requisite integration skills should be given to all Physics teachers.   Article visualizations

Meth­yl(phen­yl)phosphinic acid

The crystal structure of the title compound, C7H9O2P, displays O—H⋯O hydrogen bonding , which links individual mol­ecules related via the c-glide plane and translational symmetry along the crystallographic b-axis direction into continuous chains

Tight-Binding Molecular Dynamics Simulations on Point Defects Diffusion and Interactions in Crystalline Silicon

Tight-binding molecular dynamics (TBMD) simulations are performed (i) to evaluate the formation and binding energies of point defects and defect clusters, (ii) to compute the diffusivity of self-interstitial and vacancy in crystalline silicon, and (iii) to characterize the diffusion path and mechanism at the atomistic level. In addition, the interaction between individual defects and their clustering is investigated

Structure and electrical behavior relationship of a magnesium–tellurite glass using Raman and impedance spectroscopy

In this paperwe present the study of the glassy systems of formula: xMgO(1−x)(0.5V2O5·0.5MoO3)2TeO2,with (0 b x b 1). The aim of the work is to understand the relationship between in the induced changes in the glassy matrix by the incorporation of MgO in a vanadium–tellurite glass and the electrical response of the material. It has been found that the incorporation of MgO in the glassy matrix raises the glass transition temperature. The whole system's electrical behavior is explained by the small polaron hopping, in good agreement with the variable range polaron hopping model. In this matrix, an ionic transport by Mg2+ is not allowed. The study gives an opportunity to understand how to tune in the middle-range glassy structural order and, as a direct implication, how to control the electrical conduction process.Instituto de Física La Plat

Xanthogranulomatous Cholecystitis Mimicking as Gallbladder Carcinoma：A Caution for Hepatobiliary Surgeon

Background: Xanthogranulomatous Cholecystitis (XGC) is a destructive inflammatory process of the gall bladder which can rarely extend into neighboring structures mimicking advanced carcinoma of the gall bladder. To the best of our knowledge six such cases have been reported in medical literature in which Xanthogranulomatous cholecystitis had lead to involvement of surrounding structures. Preoperative diagnosis of such a lesion remains difficult and most of such cases are diagnosed postoperatively following resectional surgery. Case Presentation: A 40 years old lady was admitted with the clinical picture of cholecystitis and gastric outlet obstruction. Ultrasonography showed gall stones with pericholecystic collection communicating with GB lumen. CT scan showed a mass arising from gallbladder with pericholecystic fluid with gross distension of the stomach. LFTs, CEA and CA 19-9 levels were within normal limits. Endoscopy of the stomach showed an apparently non-epithelial rounded mass projecting into gastric lumen causing partial obstruction of the gastric outlet. On exploration, a firm mass involving gallbladder and stomach was identified for which en-bloc extended cholecystectomy and Billroth-II gastrectomy was performed. Histopathology of the specimen revealed XGC with secondary involvement of pylorus of the stomach.Conclusion: Given the rarer preoperative diagnosis of XGC, which morphologically and radiologically mimics carcinoma, such cases should be managed aggressively. A brief literature review has also been discussed

Structure and electrical behavior relationship of a magnesium–tellurite glass using Raman and impedance spectroscopy

In this paperwe present the study of the glassy systems of formula: xMgO(1−x)(0.5V2O5·0.5MoO3)2TeO2,with (0 b x b 1). The aim of the work is to understand the relationship between in the induced changes in the glassy matrix by the incorporation of MgO in a vanadium–tellurite glass and the electrical response of the material. It has been found that the incorporation of MgO in the glassy matrix raises the glass transition temperature. The whole system's electrical behavior is explained by the small polaron hopping, in good agreement with the variable range polaron hopping model. In this matrix, an ionic transport by Mg2+ is not allowed. The study gives an opportunity to understand how to tune in the middle-range glassy structural order and, as a direct implication, how to control the electrical conduction process.Instituto de Física La Plat

Fate of nutrients during hydrothermal treatment of food waste

Hydrothermal carbonization was evaluated as a food waste valorization strategy to obtain hydrochar and recover nutrients. In the hydrothermal treatment, the temperature (170–230 °C), reaction time (5–60 min), and addition of HCl (0.1–0.5 M) during the reaction were analyzed. Compared to the feedstock, hydrochar showed an increase in fixed carbon (greater than 45%) and a decrease in ash content (<7%), along with a higher heating value (18.6–26.2 MJ/kg), which would allow for its application as a biofuel for industry according to ISO/TS 17225–8. The hydrochar obtained using plain carbonization showed 75% P and 40% N of the feedstock content, whereas the HCl-mediated treatment (0.5 M) solubilized most of the P, K, and N in the process water (98% P as PO4-P, 98% K, and the total N content as NH4-N (16%) and organic-N) operating at 170 °C for 60 min.The authors greatly appreciate funding from Spanish MICINN (Project PID2019-108445RB-I00) and Madrid Regional Government (Project S2018/EMT-4344). A. Sarrion wishes to thank the Spanish MICINN and ESF for a research grant (BES-2017-081515). The authors thank Silvia Rodríguez for her valuable hel