Electric Field Effects on Curved Graphene Quantum Dots.

The recent and continuous research on graphene-based systems has opened their usage to a wide range of applications due to their exotic properties. In this paper, we have studied the effects of an electric field on curved graphene nanoflakes, employing the Density Functional Theory. Both mechanical and electronic analyses of the system have been made through its curvature energy, dipolar moment, and quantum regeneration times, with the intensity and direction of a perpendicular electric field and flake curvature as parameters. A stabilisation of non-planar geometries has been observed, as well as opposite behaviours for both classical and revival times with respect to the direction of the external field. Our results show that it is possible to modify regeneration times using curvature and electric fields at the same time. This fine control in regeneration times could allow for the study of new phenomena on graphene.

Quantum Revivals in Curved Graphene Nanoflakes.

Graphene nanostructures have attracted a lot of attention in recent years due to their unconventional properties. We have employed Density Functional Theory to study the mechanical and electronic properties of curved graphene nanoflakes. We explore hexagonal flakes relaxed with different boundary conditions: (i) all atoms on a perfect spherical sector, (ii) only border atoms forced to be on the spherical sector, and (iii) only vertex atoms forced to be on the spherical sector. For each case, we have analysed the behaviour of curvature energy and of quantum regeneration times (classical and revival) as the spherical sector radius changes. Revival time presents in one case a divergence usually associated with a phase transition, probably caused by the pseudomagnetic field created by the curvature. This could be the first case of a phase transition in graphene nanostructures without the presence of external electric or magnetic fields.

Gaussian Curvature Effects on Graphene Quantum Dots.

In the last few years, much attention has been paid to the exotic properties that graphene nanostructures exhibit, especially those emerging upon deforming the material. Here we present a study of the mechanical and electronic properties of bent hexagonal graphene quantum dots employing density functional theory. We explore three different kinds of surfaces with Gaussian curvature exhibiting different shapes-spherical, cylindrical, and one-sheet hyperboloid-used to bend the material, and several boundary conditions regarding what atoms are forced to lay on the chosen surface. In each case, we study the curvature energy and two quantum regeneration times (classic and revival) for different values of the curvature radius. A strong correlation between Gaussian curvature and these regeneration times is found, and a special divergence is observed for the revival time for the hyperboloid case, probably related to the pseudo-magnetic field generated by this curvature being capable of causing a phase transition.

Hamiltonian structure of compartmental epidemiological models.

Any epidemiological compartmental model with constant population is shown to be a Hamiltonian dynamical system in which the total population plays the role of the Hamiltonian function. Moreover, some particular cases within this large class of models are shown to be bi-Hamiltonian. New interacting compartmental models among different populations, which are endowed with a Hamiltonian structure, are introduced. The Poisson structures underlying the Hamiltonian description of all these dynamical systems are explicitly presented, and their associated Casimir functions are shown to provide an efficient tool in order to find exact analytical solutions for epidemiological models, such as the ones describing the dynamics of the COVID-19 pandemic.

Arboviral infections diagnosed in a European area colonized by Aedes albopictus (2009-2013, Catalonia, Spain).

BACKGROUND: The invasive mosquito Aedes albopictus, with proven vectorial ability to transmit European autochthonous cycles of dengue and chikungunya virus, has currently colonized every coastal department of Eastern Spain. The main objective of the study was to define the epidemiological and clinical characteristics as well as the trends of these two arboviral diseases in a European area heavily colonized by Ae. albopictus. METHOD: A voluntarily-based, prospective and multicenter surveillance study was performed in all medical units of the North Metropolitan area of Barcelona (406,000 inhabitants, Catalonia; Spain) with diagnostic capability from 2009 to 2013. Since any possible increase in arboviral cases could be justified by changes in traveling behaviors along the study period (especially longer trips) the trend showed by these two arboviral diseases was compared with that displayed by malaria cases during the same period. RESULTS: 38 out of 52 (73.1%) suspected cases could be serologically confirmed (IgM+): dengue 34/38 (89.5%) and chikungunya 4/38 (11.5%). No autochthonous cases were identified. The overall incidence of both arboviruses was 0.19 cases/10,000 inhabitants-year (95% CI: 0.07-0.3); dengue = 0.17 cases/10,000 inhabitants-year (95% CI: 0.05-0.3), and chikungunya = 0.02 cases/10,000 inhabitants-year (95% CI: 0.001-0.03). The Incidence Relative Risk of arboviral disease between 2009 and 2013 shown a significant trend (IRR = 1.27. IC 95%: 1.01-1.59; p = 0.043) when compared with that displayed by malaria (IRR = 1.04. IC 95%: 0.924-1.192). If no unexpected circumstances concur, the arboviral disease incidence tax would equal that of malaria about 2021-2022. CONCLUSIONS: The incidence of dengue and chikungunya is steadily increasing in the North Metropolitan area of Barcelona, a region densely colonized by Ae. albopictus, at the entire expense of imported cases (especially Visiting Friends and Relatives travelers). To date, no secondary autochthonous cases have been identified and, thus, they have not taken part in this rise.

Strongyloides stercoralis, the hidden worm. Epidemiological and clinical characteristics of 70 cases diagnosed in the North Metropolitan Area of Barcelona, Spain, 2003-2012.

BACKGROUND: The nematode Strongyloides stercoralis has a very particular autoinfection life-cycle which leads to chronic infections remaining undetected for decades. However, hyperinfection can occur in patients receiving immunotherapy resulting in high mortality rates. The main objective of this study was to assess the results of a 10-year multicenter surveillance program performed in an area with dense immigration in Barcelona, Spain. METHODS: From January 2003 to December 2012, all individuals with Strongyloides stercoralis infection attending the four centers with diagnostic capability in the North Metropolitan area of Barcelona were recorded. RESULTS: The annual detection rate was 0.2 new diagnosed cases x10 000 inhabitants/year and 1 case x10 000 immigrants/year. Many patients were immigrants (63; 90.0%), asymptomatic (45; 64.3%) and with a high eosinophil count (63; 90.0%). Immunosuppression was present in 11 (15.7%) patients, among whom two (2.8%) cases of disseminated hyperinfection were recorded. Ivermectin was prescribed in 45 (76.3%) and albendazole in 14 (23.7%). Following treatment seven patients (11.9%) receiving albendazole presented relapse, that is, albendazole failed to clear the parasite in 50% of these drug-treated patients (p < 0.001). CONCLUSIONS: During the study period, 90% of the cases of Strongyloides stercoralis diagnosed could be considered as imported by immigrants, most being asymptomatic and with eosinophilia. The infection is probably largely underestimated and population-based studies are needed to determine its true prevalence. Meanwhile, diagnosis must be based on active investigation of the helminth (serology and feces culture), especially in immunocompromised patients. The implementation of pre-immunosuppression protocols with the aim of identifying Strongyloides stercoralis is encouraged with empirical treatment with ivermectin being recommended in sites without diagnostic facilities.

[Clinical value of the ankle-brachial index in patients at risk of cardiovascular disease but without known atherothrombotic disease: VITAMIN study]. / Valor de la determinación del índice tobillo-brazo en pacientes de riesgo vascular sin enfermedad aterotrombótica conocida: estudio VITAMIN.

INTRODUCTION AND OBJECTIVES: Detecting peripheral arterial disease by measuring the ankle-brachial index can help identify asymptomatic patients with established disease. We investigated the prevalence of peripheral arterial disease (i.e., an ankle-brachial index <0.9) and its potential clinical and therapeutic impact in patients with no known arterial disease who were seen at internal medicine departments. METHODS: This multicenter, cross-sectional, observational study included patients at risk of cardiovascular disease who were selected on the basis of age, gender and the presence of conventional risk factors. No patient was known to have arterial disease. RESULTS: The study included 493 patients, 174 (35%) of whom had diabetes, while 321 (65%) did not. Only 16% were in a low-risk category according to their Framingham score. An ankle-brachial index <0.9 was observed in 27.4%, comprising 37.9% of those with diabetes and 21.3% of those without. Multiple logistic regression analysis showed that the risk factors associated with an ankle-brachial index <0.9 were age, diabetes, and hypercholesterolemia. There was a significant relationship between the ankle-brachial index and Framingham risk categories. Therapeutically, only 21% of patients with an ankle brachial index <0.9 were taking antiplatelet drugs. Overall, 20% had a low-density lipoprotein cholesterol concentration <100 mg/dl and 52% had a concentration <130 mg/dl. Some 42% had arterial blood pressures below 140/90 mm Hg. CONCLUSIONS: Asymptomatic peripheral arterial disease was detected in a high proportion of patients with an intermediate or high cardiovascular disease risk. The ankle-brachial index should be measured routinely in patients at risk of cardiovascular disease who are seen at internal medicine departments.

Results of a study of prolonging treatment with pegylated interferon-alpha2a plus ribavirin in HIV/HCV-coinfected patients with no early virological response.

OBJECTIVE: To assess the efficacy and safety of an extended treatment period in HIV/hepatitis C virus (HCV)-coinfected patients without early virological response (EVR). METHODS: Patients received pegylated interferon (peg-INF)-alpha2a 180 microg/week plus ribavirin 800 mg/d for 12 weeks. Patients achieving EVR at week 12 continued under therapy for an additional 12 or 36 weeks depending on genotype. Patients without EVR were randomized to complete the standard treatment or treatment lasting 72 weeks (extension arm). RESULTS: One hundred and ten patients were included (mean age 38.7 years, mean weight 68 kg, 74% males, 74% on highly active antiretroviral therapy, mean CD4+ T-cell count 564 cells/mm3). Fifty-one patients harboured genotype 1, 44 genotype 2/3, and 15 genotype 4. Fifty-three had an HCV load >800,000 IU/ml. Premature interruptions occurred in 32.7%. EVR was achieved in 63.6% (51% in genotype 1, 88.6% in genotype 2/3, 33.3% in genotype 4). End-of-treatment response was 52.7% (47.2% in genotype 1, 68.2% in genotype 2/3, 26.7% in genotype 4). Sustained virological response (SVR) was achieved in 41.8% (37.3% in genotype 1, 54.6% in genotype 2/3, 20% in genotype 4). Only one patient allocated to the extended arm achieved SVR. The rate of drop-outs in the extension arm was 68%. The negative predictive value of EVR was 97.5%. CONCLUSIONS: This study shows no benefit of extending therapy in patients without EVR at week 12. Measures to improve adherence to HCV antiviral therapy should be considered when new approaches based on extended periods of treatment are investigated.

Valor de la determinación del índice tobillo-brazo en pacientes de riesgo vascular sin enfermedad aterotrombótica conocida: estudio VITAMIN / Clinical value of the ankle-brachial indexin patients at risk of cardiovascular disease but without known atherothrombotic disease: VITAMIN study

Introducción y objetivos. La detección de la enfermedad arterial periférica, mediante el índice tobillo-brazo, permite identificar a los pacientes asintomáticos con una lesión establecida. Investigamos la prevalencia de enfermedad arterial periférica (índice tobillo-brazo < 0,9) en sujetos sin enfermedad arterial conocida atendidos en el ámbito de medicina interna y su potencial impacto clínico-terapéutico. Métodos. Estudio multicéntrico, transversal, observacional en el que se incluyó a pacientes con potencial riesgo cardiovascular, seleccionados en función de la edad, el sexo y la presencia de factores de riesgo convencionales, pero sin enfermedad arterial conocida. Resultados. Se evaluaron 493 casos, de los que 174 eran diabéticos (35%) y 321, no diabéticos (65%). Sólo un 16% presentó un riesgo bajo según la ecuación de Framingham. Del total de la muestra, el índice tobillo-brazo fue < 0,9 en el 27,4% (el 37,9% de los diabéticos y el 21,3%, de los no diabéticos). En el análisis multivariable, los parámetros que se asociaron con un índice tobillo-brazo < 0,9 fueron la edad, la diabetes mellitus y la hipercolesterolemia. Se objetivó una relación significativa entre las categorías de riesgo de Framingham y el índice tobillo-brazo. Al considerar a los pacientes con un índice tobillo-brazo < 0,9, sólo el 21% recibía tratamiento antiagregante, el 20% presentaba valores de colesterol unido a lipoproteínas de baja densidad (LDL) < 100 mg/dl (el 52% con LDL < 130 mg/dl) y el 42% tenía unos valores de presión arterial < 140/90 mmHg. Conclusiones. En una proporción elevada de pacientes con riesgo cardiovascular intermedio o alto se detecta enfermedad arterial periférica asintomática. El índice tobillo-brazo debería medirse sistemáticamente en enfermos con riesgo vascular, evaluados en el ámbito de la medicina interna

Introduction and objectives. Detecting peripheral arterial disease by measuring the ankle-brachial index can help identify asymptomatic patients with established disease. We investigated the prevalence of peripheral arterial disease (i.e., an ankle-brachial index <0.9) and its potential clinical and therapeutic impact in patients with no known arterial disease who were seen at internal medicine departments. Methods. This multicenter, cross-sectional, observational study included patients at risk of cardiovascular disease who were selected on the basis of age, gender and the presence of conventional risk factors. No patient was known to have arterial disease. Results. The study included 493 patients, 174 (35%) of whom had diabetes, while 321 (65%) did not. Only 16% were in a low-risk category according to their Framingham score. An ankle-brachial index <0.9 was observed in 27.4%, comprising 37.9% of those with diabetes and 21.3% of those without. Multiple logistic regression analysis showed that the risk factors associated with an ankle-brachial index <0.9 were age, diabetes, and hypercholesterolemia. There was a significant relationship between the ankle-brachial index and Framingham risk categories. Therapeutically, only 21% of patients with an ankle brachial index <0.9 were taking antiplatelet drugs. Overall, 20% had a low-density lipoprotein cholesterol concentration <100 mg/dl and 52% had a concentration <130 mg/dl. Some 42% had arterial blood pressures below 140/90 mm Hg. Conclusions. Asymptomatic peripheral arterial disease was detected in a high proportion of patients with an intermediate or high cardiovascular disease risk. The ankle-brachial index should be measured routinely in patients at risk of cardiovascular disease who are seen at internal medicine departments

High prevalence of human papillomavirus infection in the anus, penis and mouth in HIV-positive men.

Human papillomavirus (HPV) types are associated with squamous cell cancers. HIV infection is linked with a higher prevalence of anal HPV infection. It is important to assess whether HPV is present in other body parts involved in sexual practices to establish a cancer prevention program. A high prevalence of high-risk HPV types was present in the anus, penis and mouth (78, 36 and 30%, respectively) in a cohort of HIV-infected males (men who have sex with men and heterosexual), without evidence of pathology in these areas.

Role of viral kinetics under HCV therapy in HIV/HCV-coinfected patients.

Patients coinfected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) are less responsive to anti-HCV therapies and are at a higher risk of toxicity than HCV monoinfected patients. HCV viral kinetics is the basis for the study of response to interferon-based therapy and for predicting sustained virological response (SVR). A lack of early virological response (EVR; undetectable HCV RNA or a decrease of >/=2 log(10) from baseline) after 12 weeks of pegylated interferon (peg-IFN) plus ribavirin (RBV) is an equally reliable predictor of lack of SVR in HIV/HCV-coinfected patients and in the monoinfected HCV population. Early stopping rules are particularly important in coinfected HIV/HCV patients, considering their low chances of response in the more difficult-to-treat HCV genotypes 1 and 4 (<30%). Several factors have been involved in this low efficacy, including higher baseline HCV viraemia, slower viral kinetics decay under interferon pressure and a defective immune substratum. A better understanding of HCV viral kinetics under HCV therapy may be the basis for assaying different peg-IFN plus RBV schedules, such as induction or extending strategies, and may help physicians to make tailored decisions for the management of their patients.

Early HCV dynamics on Peg-interferon and ribavirin in HIV/HCV co-infection: indications for the investigation of new treatment approaches.

OBJECTIVES: To describe the 28-day hepatitis C virus (HCV) kinetics under Pegylated-interferon (Peg-IFN) + ribavirin (RBV) therapy in HIV/HCV co-infected patients. To evaluate the predictive value of early virological response (EVR) of achieving a sustained virological response (SVR). To investigate the baseline mutations in the interferon sensitivity determining region (ISDR)2209-2248 in the non-structural 5A protein of HCV according to genotype. METHODS: Open, prospective trial including 28 co-infected patients with directly observed treatment with Peg-IFN + RBV. We assessed the predictive values of EVR (> or = 2 log10 of HCV decay or a negative qualitative test) at days 1, 7, 28 and in week 12 of the SVR. RESULTS: The SVR in an intention-to-treat analysis was 28.6% (genotype 1, 1/13; genotype 3, 6/10; genotype 4, 1/5). Patients who reached SVR presented a significantly faster HCV plasma viral load reduction compared to non-responders from the first 24 h [-1.06 log10 (interquartile range, -1.7 to -0.4) versus -0.05 log10 (interquartile range, -0.4 to +0.14) respectively; P = 0.002]. The median HCV viral load at week 12 was significantly different from that at baseline in responder and transient responders but not in non-responder patients. The positive predictive value was 100% within the first month and the best negative predictive value was 92% and 88.8% at weeks 4 and 12 respectively. The only genotype 1 responder patient had eight mutations in ISDR2209-2248. CONCLUSIONS: A very early HCV viral decay is observed in responder patients. An early virological response assessment at week 4 and 12 might be a useful tool in the clinical management of the co-infected population.

Clostridium difficile colitis associated with valaciclovir.

OBJECTIVE: To report a case of Clostridium difficile colitis associated with valaciclovir treatment. CASE SUMMARY: A 73-year-old man with lumbar herpes-zoster started valaciclovir 1 g tid. After three days he began vomiting and developed diarrhea, three to four stools per day. Symptoms worsened over the following days and he was admitted. Valaciclovir was stopped and fluid and electrolyte replacement was started. He continued 6 days later with diarrhea of 7 to 13 stools per day and a stool test for diagnosis of C. difficile infection was performed with a positive result. The patient received oral metronidazole (500 mg/t.i.d. for 10 days) and rapid improvement and eventual resolution of his diarrhea was observed after 3 days of therapy. DISCUSSION: Although no conclusive reports of this reaction exist, we think this is a case of C difficile colitis that appeared three days after valaciclovir was initiated. Colitis improved with metronidazole. Other causes of diarrhea were excluded, such as diabetes mellitus, renal failure, intestinal surgery and intestinal obstruction. Infection was confirmed by a positive test for C. difficile. The application of Naranjo's algorithm asserts the reaction as 'probable'. CONCLUSIONS: Valaciclovir-associated C. difficile colitis, although rare, can have severe consequences for the patient's health. It should be included as a possible adverse effect of valaciclovir treatment by health professionals.

Advanced liver fibrosis in HIV/HCV-coinfected patients on antiretroviral therapy.

HIV infection is believed to adversely affect the progression of hepatitis C virus (HCV)-related liver disease. However, information regarding HIV and HCV coinfection in the era of highly active antiretroviral therapy (HAART) is scarce. A cross-sectional study in 75 HCV/HIV-coinfected patients (most of them on HAART) and 75 HCV-monoinfected patients paired by age, sex, and date of liver biopsy analyzed the association of HIV infection with advanced liver fibrosis (Knodell fibrosis stages 3 + 4). The median CD4 cell count in HIV-coinfected patients was 546 cells/microl; 78.7% had an HIV-1 viral load <1000 copies/ml and 88% were on antiretroviral therapy. The percentage of patients harboring genotype 4 and with a higher HCV viral load was greater in the HIV-coinfected group. HCV/HIV-coinfected patients had more advanced liver fibrosis (Knodell fibrosis stages 3 + 4) than HCV-monoinfected patients (46.7% vs. 12%, p < 0.0001). In the univariate analysis, the factors associated with advanced liver disease were male sex (OR: 2.7, 95% CI: 1.05-7.1), history of injecting drug use (OR: 4.6, 95% CI: 2.0-10.2), HIV infection (OR: 6.4, 95% CI: 2.7-14.7), and previous exposure to therapy with protease inhibitors (OR: 3.0, 95% CI:1.4-6.3). In the multivariate analysis; only male sex (OR: 3.17, 95% CI: 1.152-8.773) and HIV infection (OR: 6.85, 95% CI: 2.93-16.005) were associated with advanced liver fibrosis. HIV infection is associated with advanced liver fibrosis. HIV/HCV-coinfected individuals on HAART are at risk of developing end-stage liver disease despite virological success and immunological reconstitution.

Mitochondrial effects of a 24-week course of pegylated-interferon plus ribavirin in asymptomatic HCV/HIV co-infected patients on long-term treatment with didanosine, stavudine or both.

BACKGROUND: It has been suggested that the addition of ribavirin (RBV) as a part of the treatment for chronic hepatitis C virus (HCV) in HIV co-infected patients on didanosine (ddI) or stavudine (d4T) might increase the nucleoside-induced impairment of mitochondrial function. DESIGN: Comparative study to investigate the impact on mitochondrial function of adding RBV to a long-term treatment with ddI, d4T or both in HCV/HIV non-cirrhotic, asymptomatic patients. We included 26 patients: 16 continued with their current antiretroviral therapy (control group) and 10 patients received a concomitant 24-week course of RBV plus pegylated interferon (PEG-IFN) alpha-2b therapy (HCV-treated group). METHODS: We assessed peripheral blood mononuclear cells mitochondrial DNA (mtDNA) content and mitochondrial respiratory chain (MRC) function at baseline and at 24 weeks of follow-up. In the HCV-treated group we performed additional determinations at 12 weeks during anti-HCV therapy and 24 weeks after finishing anti-HCV therapy. RESULTS: Times on ddI or d4T exposure were 194 +/- 54.9 and 131 +/- 66.5 weeks in the HCV-treated and control groups, respectively. There were no differences either in mtDNA content, the enzyme activity of MRC complexes or clinical parameters at baseline. Throughout the study, mitochondrial measurements remained stable within groups and without differences when we compared HCV-treated and control groups. CONCLUSIONS: In our study, the addition of RBV and PEG-IFN during a 24-week period in HCV/HIV non-cirrhotic, asymptomatic patients on long-term ddI, d4T or both had no impact on mitochondrial function. These findings could suggest that additional triggers are required to achieve a critical threshold in the degree of mitochondrial damage needed for symptoms to develop.

Alternativas de recolección y tratamiento de aguas residuales de la localidad de Colquencha

Los objetivos son estudiar alternativas de diseño del sistema de recolección considerando los criterios de la norma boliviana de diseño de sistemas de alcantarillado y tratamiento de aguas residuales NB-688 de diciembre de 2001, así como alternativas de tratamiento de agua Residual que se adapten a las condiciones de la zona del proyecto.