Electron-hole asymmetry in two-terminal graphene devices

A theoretical model is proposed to describe asymmetric gate-voltage dependence of conductance and noise in two-terminal ballistic graphene devices. The model is analyzed independently within the self-consistent Hartree and Thomas-Fermi approximations. Our results justify the prominent role of metal contacts in recent experiments with suspended graphene flakes. The contact-induced electrostatic potentials in graphene demonstrate a power-law decay with the exponent varying from -1 to -0.5. Within our model we explain electron-hole asymmetry and strong Fabri-Perot oscillations of the conductance and noise at positive doping, which were observed in many experiments with submicrometer samples. Limitations of the Thomas-Fermi approximation in a vicinity of the Dirac point are discussed.Comment: 7 pages, 8 figure

Editorial: Microplastics in the marine environment: Sources, distribution, biological effects and socio-economic impacts

inexistenteinfo:eu-repo/semantics/publishedVersio

The late Oligocene flora from the Río Leona Formation, Argentinian Patagonia

A late Oligocene plant macrofossil assemblage is described from the Río Leona Formation, Argentinian Patagonia. This includes a fern, “Blechnum turbioensis” Frenguelli, one species of conifer, and sixteen angiosperm taxa. Rosaceae, Myrtaceae, Proteaceae, Lauraceae, Anacardiaceae and Typhaceae are represented by one species in each family. Five species are considered to be members of the Fabales. Three leaf taxa together with Carpolithus seeds are placed in the Nothofagaceae. Palynomorphs and permineralized woods complete the floral record of the Río Leona Formation, which is considered early late Oligocene based on radiometric dating and palynofloras

Determinants of mother to child transmission of HIV among HIV exposed infants managed in Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria

Background: Mother to child transmission of HIV (MTCT) is globally known to be the major route of spread of HIV to the unborn fetus and neonate. Many factors related to the mother, infant or the type of HIV virus interplay to increase the risk of MTCT of the virus. Antepartum antiretroviral drugs administration reduces the maternal viral load therefore lowering   the risk of transmission. The objective is to determine infection rate and assess determinants of MTCT of HIV exposed infants delivered in UDUTH Sokoto.Methods: It was a 5-year retrospective study. Records of all HIV positive pregnant women and their babies managed in UDUTH were reviewed from the E health system of the hospital. Patient’s details were recorded from booking to delivery for the period under study. The infant’s records were retrieved and information from delivery to 18 months post-delivery obtained. Structured data collection tool was developed to compile the required information. Data was analyzed using SPSS IBMS 22. Descriptive statistics and comparisons between variables were made statistically using Chi square. P value of   ≤ 0.005 was considered as significant.Results: Records of all the patients recruited were all available for evaluation because authors use the E-health system of records keeping in our hospital. MTCT rate was 0.92%. Majority 60 (47.2%) were within age group 26-30yrs. The subjects were predominantly house wives 97(71.4%) and multipara 77 (60.6%). Viral load ranged between 112 to 28228 copies/ml. Twenty-two (17.3%) had CD4 count less than 250 cells/µl while 61 (48%) had counts above 500cells/µl. All were in WHO clinical stage 1-3. All were on triple regimen anti-retroviral drugs. Spontaneous rupture of membranes for over 4 hours occurred in 51(32%). Vaginal delivery was recorded in 89.7%. Breast feeding was practiced by 48%.Conclusions: Breast-feeding still remains a risk factor for MTCT OF HIV Early administration of   maternal antiretroviral drugs significantly reduces the rate of mother to child transmission of HIV

Knowledge and acceptability of prenatal diagnosis among pregnant women attending antenatal clinic in a tertiary health institution in Sokoto, Nigeria

Background: Technology and advances in research have made it possible for the fetus to become a patient whose illness can be investigated, diagnosed and treated in utero. The study was aimed at assessing the knowledge and acceptability of prenatal diagnosis among pregnant women.Methods: This was a cross-sectional study carried out between December 2016 and March, 2017. Pregnant women attending antennal care clinic at the Usmanu Danfodiyo University Teaching Hospital, Sokoto (UDUTH) were recruited via convenient sampling method using semi-structured interviewer questionnaire.Results: A total of 417 pregnant women were interviewed. The mean maternal age was 28.35±5 years with a range between 17 to 45 years. Up to 188 (69.10%) had at least secondary school level of education. There was an overall poor knowledge of prenatal diagnosis, as 406 (97.36%) had little to no idea. There was statistically significant association between knowledge and educational status at p value- 0.0001. Majority, 353 (87.8%) will accept prenatal diagnosis if offered. There was also statistically significant association between educational status and acceptability as well as knowledge of prenatal diagnosis at p value- 0.001 and 0.001 respectively. The noninvasive method, ultrasound was the most preferred by the majority, 332 (84.3%). Termination of pregnancy as an option of management in fetal abnormality was acceptable by up to 2/3 (63.1%) of the respondents.Conclusions: The knowledge of prenatal diagnosis among the respondents was generally poor. The identifiable factor that determined knowledge and acceptability of prenatal diagnosis was level of education

The incidence, pattern and management of sexual assault in a tertiary hospital in North-western Nigeria

Background: Sexual assault is any sexual act performed by one person on another without the person’s consent or on a victim who is incapable of giving consent. It is a violation of basic human rights, a gender-based issue and a violent crime against both the individual and the society. The objectives of the study were to determine the incidence, pattern and management of sexual assault in Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria.Methods: This was a 10 - year retrospective study. Case records of sexual assault from 1st January, 2007 to 31st December, 2016 were retrieved and relevant data extracted and analyzed using the SPSS for windows version 20.0Results: The incidence of sexual assault was 0.8%. Majority, 88 (85.4%) occurred in children and adolescents. Peno-vaginal penetration was the most common form of assault 65 (63.1%) and the assailants were known to the victims in 74 (71.9%) of the cases. Involvement of psychiatrists/psychologists in the management of the victims was poor as psychiatrists were involved in only 13 (12.6%) of the cases. Most of the victims were lost to follow up.Conclusions: Sexual assaults occurred mostly in children and adolescents in this study. Increased public awareness and preventive interventions are required especially among the at-risk age groups to enhance their safety. Training of relevant persons in the institution to offer counselling to the victims is recommended as referral for psychiatrists’ consultation was poor. It is important to institute a good tracking system to follow up the victims as most are lost to follow up.                                                               

States on pseudo effect algebras and integrals

We show that every state on an interval pseudo effect algebra $E$ satisfying some kind of the Riesz Decomposition Properties (RDP) is an integral through a regular Borel probability measure defined on the Borel $\sigma$-algebra of a Choquet simplex $K$. In particular, if $E$ satisfies the strongest type of (RDP), the representing Borel probability measure can be uniquely chosen to have its support in the set of the extreme points of $K.

Effect of hormonal and copper IUDs on genital microbial colonisation and clinical outcomes in North-Western Nigeria

Background: Intrauterine devices are one of the popular long term reversible contraceptive methods. Earlier forms were associated with genital infections, however more recent types such copper IUDs and hormonal types have been shown to have better safety profile. However, there is no conclusive evidence to demonstrate that hormonal IUD is less associated with genital infection when compared with copper IUDs. The objectives include determination of prevalence of genital tract infections among IUD users, to determine the type of IUD that is less associated with genital infection, and also determine clinical features seen among IUD users.Methods: We conducted a descriptive, cross sectional study of clients who were at 6 months following IUD insertion. Endocervical and high vaginal samples were taken to isolate microbes.Results: The prevalence of genital tract infection was 20% in Copper IUD users and 8.6% among LNG-IUS users. Genital infection was significantly higher among copper IUD users compared to hormonal IUD users (p=0.038, OR= 2.88). Abnormal vaginal discharge was the commonest symptoms among IUD users and formal education was associated with less risk of genital infections (p=0.048).Conclusions: Hormonal IUDs are less associated with genital tract infection compared to copper IUDs and women with formal education are less likely to have genital infection among IUD users

Clinical correlates of plasma antithrombin and protein C levels in patients with pre-eclampsia and eclampsia in Sokoto, Northwest Nigeria

Background: Hypertensive disorders of pregnancy complicate 17% of pregnancies in Sokoto, Nigeria with pre-eclampsia and eclampsia accounting for 6% and 4.29% respectively. Pre-eclampsia and eclampsia stand out as major causes of poor pregnancy outcomes with eclampsia contributing 46% of adolescent maternal mortality in Sokoto. These disorders increase risk of venous thromboembolism, DIC, placental abruption, IUGR, premature delivery and recurrent pregnancy loss. The roles of antithrombin and protein C in disease severity and outcomes of pregnancies in pre-eclampsia/eclampsia are subject of recent researches albeit with conflicting findings. The aim of the study was to determine the plasma antithrombin and protein C levels of pre-eclampsia and eclampsia in Sokoto with a view to assessing any relationship with clinical severity and pregnancy outcomes.Methods: Prospective comparative study involving 31 each of pregnant women with pre-eclampsia, eclampsia and normotensive pregnancy. Plasma antithrombin and protein C levels were determined via kinetic method using S4 Nortek semi-automated coagulometer. Data analysis was performed using SPSS version 21.0.  Results: The mean plasma antithrombin and protein C levels for eclampsia, pre-eclampsia and normotensive pregnancy were (61.17±9.13 and 60.00±5.76) vs (71.24±13.15 and 71.06±6.16) vs (85.54±8.77 and 89.64±7.61) respectively; p=0.0001. Severe pre-eclampsia when compared with mild pre-eclampsia had lower antithrombin (70.21±13.58 vs 73.74±12.43; p=0.507) and protein C (70.52±6.27 vs 72.40±6.00; p=0.451) levels respectively, though without statistical significance. Pre-eclampsia with low plasma antithrombin levels had increased risk of preterm delivery when age, gravidity and booking status were factored (OR, 1.2, 95% CI 0.035 to 0.348, p=0.017).Conclusions: Lower plasma antithrombin and protein C levels were found with eclampsia and severe pre-eclampsia suggesting consumptive depletion of anticoagulants with disease progression. Women with pre-eclampsia and low plasma antithrombin levels were found to have increased odds of having preterm delivery when age, gravidity and booking status were considered

Caesarean section at Usmanu Danfodiyo University Teaching Hospital: a cross sectional study

Introduction: Caesarean section remains the most common major operation performed on women worldwide and the rate is increasing.The World Health Organization (WHO) consider caesarean section rate of 5-15% to be optimum.Objective: To determine the rate of caesarean section, major indications, pregnancy out-come and the complications.Subjects and Methods:This is a prospective study of all the cases of caesarean sections performed between 1st of January,2012 and 31th of December,2013 at UDUTH,Sokoto-Nigeria.The data were collated and analyzed using statistical soft package ware for social sciences (SPSS) version 20.Results: A total of 4,115 deliveries were recorded during the study period and 435 of them (10.6%) were through caesarean section (CS). Emergency CS accounted for 65.1% of caesarean deliveries.The mean age was 28±6 years. Previous CS was the commonest indication for caesarean section (25.7%). Elective CS had better fetal outcome (t = 7.440,df =388.523,p < 0.001),while spinal anaesthesia was associated with less blood loss (t = 4.569, df=63.223 and p < 0.001) and better fetal outcome (t = 4.237, df = 57.224, p < 0.001).Anaemia (19.8%) was the commonest complications encountered in the post operative period.Conclusion: The CS rate from this study is within the WHO recommended rate. Previous CS was the commonest indication,the outcome was better among women that had elective CS under regional anaesthesia.Keywords: Caesarean section, CS rate, indication and outcom