Machine Learning Algorithms and Auditor’s Assessments of the Risks Material Misstatement: Evidence from the Restatement of Listed London Companies

The purpose of this study is to investigate the relationship between machine learning algorithms and auditors assessments of the risks of material misstatement and restatement. Additionally, a focus on the effect of machine learning algorithms (SVM, Naïve Bayes, and K-means) on misstatement and restatement in London companies. The final sample of the study is 304 firm year observations. Which covers the listed firms on the London Stock Exchange and the period from 2018 to 2020. Especially, the firms that restated their financial statements -even just once- during the study period. The results showed a positive significant effect of machine learning techniques (K-means, Naïve Bayes, and SVM) on the intentional misstatements, which means that using machine learning techniques helps in determining the intentional misstatements. The results also showed a negative significant effect of the same techniques (K-means, Naïve Bayes, and SVM) on the restatements, which means that using machine learning techniques helps in avoiding the restatements

Magnetically Torqued Thin Accretion Disks

We compute the properties of a geometrically thin, steady accretion disk surrounding a central rotating, magnetized star. The magnetosphere is assumed to entrain the disk over a wide range of radii. The model is simplified in that we adopt two (alternate) ad hoc, but plausible, expressions for the azimuthal component of the magnetic field as a function of radial distance. We find a solution for the angular velocity profile tending to corotation close to the central star, and smoothly matching a Keplerian curve at a radius where the viscous stress vanishes. The value of this ''transition'' radius is nearly the same for both of our adopted B-field models. We then solve analytically for the torques on the central star and for the disk luminosity due to gravity and magnetic torques. When expressed in a dimensionless form, the resulting quantities depend on one parameter alone, the ratio of the transition radius to the corotation radius. For rapid rotators, the accretion disk may be powered mostly by spin-down of the central star. These results are independent of the viscosity prescription in the disk. We also solve for the disk structure for the special case of an optically thick alpha disk. Our results are applicable to a range of astrophysical systems including accreting neutron stars, intermediate polar cataclysmic variables, and T Tauri systems.Comment: 9 sharper figs, updated reference

Comparison of breast sequential and simultaneous integrated boost using the biologically effective dose volume histogram (BEDVH)

Purpose: A method is presented to radiobiologically compare sequential (SEQ) and simultaneously integrated boost (SIB) breast radiotherapy. Methods: The method is based on identically prescribed biologically effective dose (iso-BED) which was achieved by different prescribed doses due to different fractionation schemes. It is performed by converting the calculated three-dimensional dose distribution to the corresponding BED distribution taking into consideration the different number of fractions for generic α/β ratios. A cumulative BED volume histogram (BEDVH) is then derived from the BED distribution and is compared for the two delivery schemes. Ten breast cancer patients (4 right-sided and 6 left-sided) were investigated. Two tangential intensity modulated whole breast beams with two other oblique (with different gantry angles) beams for the boost volume were used. The boost and the breast target volumes with either α/β = 10 or 3 Gy, and ipsi-lateral and contra-lateral lungs, heart, and contra-lateral breast as organs at risk (OARs) with α/β = 3 Gy were compared. Results: Based on the BEDVH comparisons, the use of SIB reduced the biological breast mean dose by about 3%, the ipsi-lateral lung and heart by about 10%, and contra-lateral breast and lung by about 7%. Conclusion: BED based comparisons should always be used in comparing plans that have different fraction sizes. SIB schemes are dosimetrically more advantageous than SEQ in breast target volume and OARs for equal prescribed BEDs for breast and boost

Socio-cultural determinants and impact of HIV infection in the Sudan

Background: Sudan, among the Subsaharan African countries has a low prevalence of HIV infection particularly in the North of the predominantly Muslim population. The peace agreement (2005) which stopped the civil war in the South opened the boarders with the HIV-high prevalence countries of Central and West Africa. This is expected to increase the transmission of HIV in the whole of Sudan. Methods and results: The present study interviewed 635 HIV positive individuals reporting for testing in three voluntary counseling and treatment (VCT) centres in Khartoum. Socio-cultural determinants of the infection showed that the young adults less than 50 years constitute 66.1% of all infected, with 60% males, 40% females and majority 64.9% are either illiterate or had minimum level of education. 61% of them were Muslims and 39% were Christians or non believers, 50.1% were married. The quality of life changed in 89% of individuals.Conclusion: It is concluded that the infection with HIV in Sudan may increase and health education messages need to be tailored according to the sociocultural determinants of the infection in a multicultural, multi-religious country like the Sudan. Muslims will not be protected against HIV infection unless they adhere to the code of Islam.Keywords: human immuno-deficiency virus, Muslims, Subsahara

Antibacterial and cytotoxic properties of isoprenoids from the red sea soft coral, Lobophytum sp

Purpose: To evaluate the antibacterial and cytotoxic activities of the secondary metabolites of Lobophytum sp.Methods: Maceration with methanol: chloroform (1:1) was applied to extract the coral material. Chromatographic and spectroscopic techniques were employed for fractionation, isolation and elucidation of pure compounds. Antibacterial activities were performed by well diffusion method against three Gram-positive and four Gram-negative bacteria. Brine shrimp lethality test was employed to predict toxicity, while antitumor activity were tested by 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide (MTT) method against Ehrlich carcinoma cells.Results: Four sesquiterpenes, one cembranoid type diterpenes and two steroids were isolated. 1 exhibited significant antibacterial activity against four tested bacteria (P. aeruginosa, S. aureus, S. epidermis, and S. pneumonia) with MIC value of 15 μg/mL. Moreover, 1 showed high diameter zone of inhibition ranging from 16 - 18 mm against test bacteria. Compounds 4 and 5 displayed moderate antibacterial activity against all test bacteria with inhibition zone diameter (IZD) ranging from 11 – 15 mm and MIC values of 30 μg/mL. 2, 3, 6 and 7 exhibited weak antibacterial activity (IZD, 7 - 11 mm; MIC ≥ 30 μg/mL). In addition, only diterpene compound (4) showed high toxicity against A. Salina and antitumor activity against Erhlich carcinoma cells with the LD50 of 25 and 50 μg/mL, respectively.Conclusion: This study reveals the strong antibacterial activity of sesquiterpene alismol (1) and the potential antibacterial and antitumor activity of cembranoid type diterpene, cembrene A (4).Keywords: Soft coral, Lobophytum sp., Red Sea, Antibacterial, Cytotoxicity, Sesquiterpene Alismol, Cembranoid, Diterpene, Cembren

2-Amino-4-phenyl-5,6-dihydro­benzo[h]quinoline-3-carbonitrile–3-amino-1-phenyl-9,10-dihydro­phenanthrene-2,4-dicarbonitrile (5/3)

The asymmetric unit of the 5:3 title co-crystal of 2-amino-4-phenyl-5,6-dihydro­benzo[h]quinoline-3-carbonitrile and 3-amino-1-phenyl-9,10-dihydro­phenanthrene-2,4-dicarbonitrile, 0.625C20H15N3.0.375C22H15N3, has the atoms of the fused-ring system and those of the amino, cyano and phenyl substitutents overlapped. The fused-ring system is buckled owing to the ethyl­ene linkage in the central ring, the two flanking aromatic rings being twisted by 20.1 (1)°. This ethyl­ene portion is disordered over two positions in a 1:1 ratio. The phenyl ring is twisted by 69.5 (1)° relative to the amino- and cyano-bearing aromatic ring. In the crystal, two mol­ecules are linked by an N—H⋯N hydrogen bond, generating a a helical chain along [010]

Glicerolisis de aceite de girasol catalizada por lipasa para producir glicéridos parciales.

Partial glycerides were prepared by glycerolysis of sunflower oil in presence of lipase enzyme as catalyst. Six lipases of different origins were used and compared for their catalytic activity. These include Chromobacterium lipase, pancreatic lipase, Rhizopus arrhizus lipase, lyophilized lipase (plant lipase) in addition to two lipase preparations derived from Rhizopus japonicas; Lilipase A-10 and Lilipase B-2. Chromobacterium lipase was found to be the most active as glycerolysis catalyst whereas lyophilized lipase; a plant preparation from wheat germ was the least active. The results have also shown that the lipase type affects also the product polarity and hence its field of application as a food emulsifier. Less polar products can be obtained using Chromobacterium lipase whereas the more polar ones using a fungal lipase preparation «Lipase A-10». The product polarity is also influenced by the process temperature but the mode of its effect is different for different lipases.Se prepararon glicéridos parciales mediante glicerolisis de aceite de girasol en presencia de lipasa como catalizador. Seis lipasas de orígenes diferentes se utilizaron y compararon en función de su actividad catalítica. Estas incluyeron lipasa de Chromobacterium, lipasa pancreática, lipasa de Rhizopus arrhizus, lipasa liofilizada (lipasa vegetal) además de dos preparaciones de lipasa derivadas de Rhizopus japonicus: lilipase A-10 y lilipase B-2. Se encontró que la lipasa de Chromobacterium fue la más activa como catalizador en la glicerolisis mientras que la lipasa liofilizada, preparación vegetal a partir de germen de trigo, fue la menos activa. Los resultados mostraron que los tipos de lipasa afectan también a la polaridad de los productos y por tanto a los rendimientos en su aplicación como emulsificantes alimentarios. Los productos menos polares pueden obtenerse usando lipasa de Chromobacterium mientras que los más polares se obtienen usando las preparaciones de lipasa de hongo «Lilipase A-10». La polaridad del producto está también influenciada por la temperatura del proceso aunque la forma de su efecto es distinta para las diferentes lipasas

A Look at the Global Impact of COVID-19 Pandemic on Neurosurgical Services and Residency Training

BACKGROUND: The COVID-19 pandemic has left an indelible effect on healthcare delivery and education system, including residency training. Particularly, neurosurgical departments worldwide had to adapt their operating model to the constantly changing pandemic landscape. This review aimed to quantify the reduction in neurosurgical operative volume and describe the impact of these trends on neurosurgical residency training. METHODS: We performed a comprehensive search of PubMed and EMBASE between December 2019 and October 2022 to identify studies comparing pre-pandemic and pandemic neurosurgical caseloads as well as articles detailing the impact of COVID-19 on neurosurgery residency training. Statistical analysis of quantitative data was presented as pooled odds ratio (OR) and 95% confidence intervals (CI). RESULTS: A total of 49 studies met the inclusion criteria, of which 12 (24.5%) were survey-based. The case volume of elective surgeries and non-elective procedures decreased by 70.4% (OR=0.296, 95%CI 0.210-0.418) and 68.2% (OR=0.318, 95%CI 0.193-0.525), respectively. A significant decrease was also observed in functional (OR=0.542, 95%CI 0.394-0.746), spine (OR=0.545, 95%CI 0.409-0.725), and skull base surgery (OR=0.545, 95%CI 0.409-0.725), whereas the caseloads for tumor (OR=1.029, 95%CI 0.838-1.263), trauma (OR=1.021, 95%CI 0.846-1.232), vascular (OR=1.001, 95%CI 0.870-1.152), and pediatric neurosurgery (OR=0.589, 95%CI 0.344-1.010) remained relatively the same between pre-pandemic and pandemic periods. The reduction in caseloads had caused concerns among residents and program directors in regard to the diminished clinical exposure, financial constraints, and mental well-being. Some positives highlighted were rapid adaptation to virtual educational platforms and increasing time for self-learning and research activities. CONCLUSION: While COVID-19 has brought about significant disruptions in neurosurgical practice and training, this unprecedented challenge has opened the door for technological advances and collaboration that broaden the accessibility of resources and reduce the worldwide gap in neurosurgical education

Scattering from Singular Potentials in Quantum Mechanics

In non-relativistic quantum mechanics, singular potentials in problems with spherical symmetry lead to a Schrodinger equation for stationary states with non-Fuchsian singularities both as r tends to zero and as r tends to infinity. In the sixties, an analytic approach was developed for the investigation of scattering from such potentials, with emphasis on the polydromy of the wave function in the r variable. The present paper extends those early results to an arbitrary number of spatial dimensions. The Hill-type equation which leads, in principle, to the evaluation of the polydromy parameter, is obtained from the Hill equation for a two-dimensional problem by means of a simple change of variables. The asymptotic forms of the wave function as r tends to zero and as r tends to infinity are also derived. The Darboux technique of intertwining operators is then applied to obtain an algorithm that makes it possible to solve the Schrodinger equation with a singular potential containing many negative powers of r, if the exact solution with even just one term is already known.Comment: 19 pages, plain Tex. In this revised version, the analysis of Eq. (5.29) has been amended, and an appendix has been added for completenes