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We study the frictional drag between two graphene layers placed inside a cavity. We show that the drag has two contributions: the well-known Coulomb drag, and a novel photon-mediated drag. The latter arises from a cavity-mediated interaction in which the backscattering is not suppressed and the screening is relatively weak. As a result, the photon-mediated drag resistivity in the Fermi-liquid regime acquires corrections to the usual quadratic temperature dependence, has a slow decay as the interlayer separationdincreases, and depends on the carrier densitynasρD∼1/n2. Thus, whereas for smalldandnthe Coulomb drag dominates, as these parameters increase the drag transitions to a purely photon-mediated drag. The onset of this transition depends on the electromagnetic field enhancement inside the cavity.

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It is well known that the confinement of matter inside a microcavity can significantly enhance the light-matter interactions. As a result the vacuum fluctuations, induced by virtual photons, can occur in a volume much lower than the free-space diffraction limit. In this work we show that, for a single doped graphene plane inside a microcavity, these enhanced vacuum interactions can produce a significant reduction in the Fermi velocity of the electrons. The effect arises because the energies of the photons are much larger than the energies of the electrons in graphene, which implies that the vacuum exchange interaction is repulsive around the Fermi level. Consequently the quasiparticle Fermi velocity decreases, in contrast with the enhancement obtained in Hartree-Fock. For THz cavities, the reduction is highly localized around the Fermi level, and is practically independent of the carrier density in graphene.

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OBJECTIVE: In 2007, the Ministry of Health (MoH) in Mexico implemented a multidisciplinary health-care model (MHC) for patients with type-2 diabetes (T2D), which has proven more effective in controlling this condition than the conventional health-care model (CHC). RESEARCH DESIGN AND METHODS: We compared the cost-effectiveness of the MHC vs. the CHC for patients with T2D using a quasi-experimental, retrospective design. Epidemiologic and cost data were obtained from a randomly selected sample of health-care units, using medical records as well as patient- and facility-level data. We modelled the cost-effectiveness of the MHC at one, 10 and 20 years using a simulation model. RESULTS: The average cumulative costs per patient at 20 years were US$4,225 for the MHC and US$4,399 for the CHC. With a willingness to pay one gross domestic product (GDP) per capita per quality-adjusted life year (QALY) (US$8,910), the incremental net benefits per patient were US$1,450 and US$3,737 at 10 and 20 years, respectively. The MHC was cost-effective from the third year onward; however, increasing coverage to 500 patients per year rendered it cost-effective at year one. CONCLUSIONS: The MHC is cost-effective at 10 and 20 years. Cost-effectiveness can be achieved in the short term by increasing MHC coverage.

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We study the electronic heat capacity in doped graphene under magnetic fields. The partition function is calculated considering only the thermal excitations in the last occupied energy levels. Due to the large energy separation between the Landau levels (LLs) and the Zeeman splitting, at low temperatures the heat capacity is dominated by the spin excitations in the last occupied LL. Correspondingly the heat capacity oscillates with maximum amplitude at half filling of each LL. At higher temperatures the inter-LLs excitations dominate the heat capacity, with maximum amplitude at full filling factors. The oscillation amplitudes are compared with the phonon heat capacity C p. It is shown that the spin induced heat capacity oscillations have a maximum amplitude approaching 3% of C p, whereas for the inter-LLs excitations the maximum amplitude is only 0.1% of C p. These amplitudes decrease in the presence of impurities, although the effect is appreciable if the LLs broadening is bigger than the excitation energies.

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We study the magnetic oscillations (MO) in 2D materials with a buckled honeycomb lattice, considering a perpendicular electric and magnetic field. At zero temperature the MO consist of the sum of four sawtooth oscillations, with two unique frequencies and phases. The values of these frequencies depend on the Fermi energy and electric field, which in turn determine the condition for a beating phenomenon in the MO. We analyse the temperature effect in the MO by considering its local corrections over each magnetization peak, given by Fermi-Dirac like functions. We show that the width of these functions is related to the minimum temperature necessary to observe the spin and valley properties in the MO. In particular, we find that in order to observe the spin splitting, the width must be lower than the MO phase difference. Likewise, in order to observe valley mixing effects, the width must be lower than the MO period. We also show that at high temperatures, all the maxima and minima in the MO shift to a constant value, in which case we obtain a simple expression for the MO and its envelope. The results obtained show unique features in the MO in 2D materials, given by the interplay between the valley and spin.

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La fonoaudiología chilena, en el contexto de la salud, concentra su práctica en el segundo y tercer nivel (hospitalario), existiendo una fuer te tradición biomédica en el área. Las orientaciones disciplinares y el contexto de la salud pública nacional invitan a fortalecer la atención primaria de la salud, desde un punto de vista preventivo y promotor. OBJETIVO: Describir las acciones del fonoaudiólogo en Atención Primaria de Salud (APS) en la Quinta Región de Valparaíso y revisar su pertinencia respecto al modelo propuesto por el Ministerio de Salud. MÉTODOS: Estudio cualitativo con enfoque fenomenológico. Se aplicó una entrevista semiestructurada a fonoaudiólgos(as) que se desempeñaban en APS y la información recopilada fue sometida a análisis de contenido. RESULTADOS: El contexto laboral de los fonoaudiólogos se circunscribe a convenios con programas que dan cobertura a un segmento específico de la población (infantil). Los fonoaudiólogos no cuentan con jornadas de trabajo completa en APS. Las acciones fonoaudiológicas se concentran en el diagnóstico, la habilitación y rehabilitación comunicativa. CONCLUSIONES: La práctica fonoaudiológica no responde actualmente al modelo de APS chileno. Es necesario incorporar una visión biopsicosocial y comunitaria a la práctica fonoaudiológica, con el fin de dar respuesta a las necesidades de la salud pública nacional.

The Community Based Rehabilitation (CBR) approach represents a strategy whose purpose is to achieve full social integration and inclusion of people with disabilities. Considering that communica tion and human language represent tools of expression of thought, the American Speech, Language and Hearing Association (ASHA) advocates the development of effective communication promotion, as a human right accessible to all people, considering its inherent dignity. OBJECTIVE: to analyze speech and language pathologist 's CBR practices in the fifth region of Valparaíso. METHOD: qualitative research, with a phenomenological approach. A semi-structured interview was conducted followed by a content analysis. RESULTS: speech and Language pathologists carry out actions related to the five CBR key components and also the practice of actions in accord to intersector. CONCLUSIONS: The professionals adopt the CBR approach incorporating the institutional vision of service in which they are inserted and adopting a profile oriented to transdisciplinary.

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We analyze the magnetic oscillations (MO) due to the de Haas-van Alphen effect, in pristine graphene under a perpendicular magnetic field, taking into account the Zeeman effect. We consider a constant Fermi energy, such that the valence band is always full and only the conduction band is available. At zero temperature the MO consist of two sawtooth peaks, one for each spin. Both peaks have the same frequency, but different amplitude and phase. We show that, in order to observe the spin splitting in the MO, Fermi energy of about 0.1 eV is required. At low temperatures we obtain that the MO can be expressed as the MO at zero temperature, plus small Fermi-Dirac like functions, each centered around the MO peaks. Using this expression, we show that the spin splitting is observable in the MO only when the thermal energy is smaller than the Zeeman energy. We also analyze the shift of the MO extrema as the temperature increases. We show that it depends on the magnetic field, which implies a broken periodicity at nonzero temperature. Finally, we obtain an analytical expression for the MO envelope. The results obtained could be used to infer temperature changes from the MO extrema shift and vice versa.

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Helicobacter pylori (H. pylori) is present in the stomach of half of the world's population. The force of infection describes the rate at which susceptibles acquire infection. In this article, we estimated the age-specific force of infection of H. pylori in Mexico. Data came from a national H. pylori seroepidemiology survey collected in Mexico in 1987-88. We modelled the number of individuals with H. pylori at a given age as a binomial random variable. We assumed that the cumulative risk of infection by a given age follows a modified exponential catalytic model, allowing some fraction of the population to remain uninfected. The cumulative risk of infection was modelled for each state in Mexico and were shrunk towards the overall national cumulative risk curve using Bayesian hierarchical models. The proportion of the population that can be infected (i.e. susceptible population) is 85.9% (95% credible interval (CR) 84.3%-87.5%). The constant rate of infection per year of age among the susceptible population is 0.092 (95% CR 0.084-0.100). The estimated force of infection was highest at birth 0.079 (95% CR 0.071-0.087) decreasing to zero as age increases. This Bayesian hierarchical model allows stable estimation of state-specific force of infection by pooling information between the states, resulting in more realistic estimates.

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The objectives of this study were to evaluate performance and causes of discontinuation of the Copper T380A IUD by users at the Family Planning Service at Hospital Arzobispo Loayza in Lima, Peru, during a period of three years. The study included 3167 acceptors of the CuT380A attending the service during 1992-1994. IUDs were inserted during interval timing. Follow-up was at 1, 12, 24 and 36 months after insertion. The following events were recorded: number of pregnancies, expulsions and all causes of discontinuation. The cumulative rates per 100 woman-years using the life-table method was calculated. Also calculated were the relative risks for expulsion and for pregnancy. At the end of the study, 361 women had discontinued the method for various reasons, whereas 1667 women continued using the method. The lost-to-follow-up proportion increased over time from 35.9 per 100 woman-years for the first year to 38.2 for the third year. The cumulative discontinuation rate over three years was 22.6 +/- 1.3 (cumulative rate +/- standard error) per 100 woman-years. The cumulative pregnancy rate for three years was 1.2 +/- 0.4 per 100 woman-years, whereas the cumulative rate of expulsion was 4.9 +/- 0.4 for the first, 6.4 for the second and 6.8 for the third year. The main cause of discontinuation during the first year of use was expulsion (4.9 per 100 woman-years) followed by personal reasons (2.1 per 100 woman-years). At the end of the third year, the main cause was personal reasons (11.4) and the second cause was expulsion (6.8). A higher probability of expulsion, pregnancy and discontinuation for bleeding and/or pain was associated with age less than 20 years. In conclusion, the effectiveness of the CuT380A IUD after three years of use was 98.8 per 100 woman-years, whereas continuation was 39.2, and loss to follow-up increased over time.

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OBJECTIVE: To determine the efficacy and safety of intravaginal misoprostol compared with intravenous oxytocin in cervical ripening and labor induction. METHOD: The study was carried out at the Department of Obstetrics and Gynecology at the Hospital Loayza, Lima, Peru. The sample included 123 pregnant women with any indication for labor induction. The study was prospective and randomized. We compared the effect of 50 micrograms of intravaginal misoprostol administered every 4 h up to 600 micrograms with that observed using the standard protocol of oxytocin by continuous infusion. RESULTS: 57 patients with misoprostol (group 1) and 63 with oxytocin (group 2) were enrolled. Delivery occurred in 45 patients (78.9%) in group 1 and in 37 (58.7%) in group 2 (P < 0.017). Complications including tachysystole, uterine hypertony and hyperstimulation were higher in group 1, 21.1% than in group 2, 7.9% (P < 0.04). The incidence of cesarean section in both groups was similar to the overall incidence in our center. No differences were observed between groups in perinatal and postpartum adverse outcomes. The interval from start of induction to vaginal delivery was significantly shorter in the oxytocin group (8.4 +/- 4.1 vs. 11.3 +/- 6.9 h, P < 0.005). CONCLUSION: Intravaginal administration of misoprostol is a safe and effective alternative for cervical ripening and labor induction. Maternal and neonatal complications did not increase significantly.

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OBJECTIVES: To determine the hormone profile during the menstrual cycle in women at sea level and at high altitude, and whether the time between the gonadotropin peak and ovulation is different at high altitude from that at sea level. METHODS: The study was carried out in Lima (150 m) and Cerro de Pasco (4340 m), Peru. The hormone profile of 10 adult regularly menstruating women at sea level and 10 women at high altitude was assessed. Ovulation was identified by vaginal ultrasonography. RESULTS: The pre-ovulatory follicle diameter was lower (P < 0.001) at high altitude than at sea level. Ovulation after LH peak occurred earlier at high altitude than at sea level. Serum FSH levels were higher at late luteal phase and early follicular phase at high altitude than at sea level (P < 0.05). The serum LH and FSH peaks were similar in women at sea level and at high altitude. During the early follicular phase serum estradiol levels were significantly higher at high altitude than at sea level (P < 0.05). During the late follicular phase the production of estradiol was higher at sea level than at high altitude (P < 0.05). The peak of serum estradiol was at day -1 in Lima and in day 0 at high altitude. At ovulation, the serum estradiol levels in women at sea level were 55.1% of the peak, but remained at high levels (80% of the peak) in women at high altitude (P < 0.05). The second increase of serum estradiol occurred earlier at sea level than at high altitude. From days +12 to +15, there was a significant decline in serum estradiol levels in women at sea level (P < 0.05) but not in those from high altitude (P > 0.05). Serum progesterone levels at days +5, and +8 to +12 were significantly higher at sea level than at high altitude. CONCLUSION: Our data suggest that hormone profile during menstrual cycle is different at high altitude than at sea level, probably as an effect of low barometric pressure.

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This was a prospective, single-blind, comparative study in patients with diagnosis of puerperal endometritis, carried out at the Loayza Hospital in Lima, Peru. The objective of this study was to evaluate the efficacy and safety of clindamycin and gentamicin in the management of endometritis vs. penicillin, chloramphenicol and gentamicin for 10 days. Sixty-five patients were enrolled and 62 were evaluable for efficacy. Both treatment groups were comparable in the pre-treatment period in terms of age, history of pregnancies, controls by gynecologist, days of disease and fever, clinical symptoms like fever, pelvic pain, pulse, uterine size and in laboratory, in hematocrit and leukocytes count. In the culture of endometrium tissue, 27/32 patients (84.4%) in Group A (penicillin + CAF + gentamicin) and 27/30 patients (90%) in Group B (clindamycin + gentamicin) had positive cultures at baseline; 18 and 22 patients showed anaerobes; 8 and 4 patients showed anaerobes plus aerobes and, one patient in each treatment group showed aerobes only. Peptostreptococcus and Bacteroides fragilis were the most frequently isolated pathogens. Improvement in lochia fetidity was more rapid in Group B, it turned transparent and not fetid since day 3. Complete cure was significantly better in Group B 24/30 (80%) in comparison with Group A 16/32 (50%) (p = 0.02). Partial response was found in 15 patients (43.3%) in Group A and 5 patients (16.6%) in Group B. Only one case was considered as bacteriological failure in Group A and only one patient in Group B was considered as failure and required an additional operation due to residual abscess.(ABSTRACT TRUNCATED AT 250 WORDS)

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Oocyte donation programs offer an alternative treatment for infertile women with ovarian failure or abnormal ovarian function. Seventeen cycles of in vitro fertilization and embryo transfer with donated oocytes were performed in 13 women, with a mean age of 34.8 years. The hormonal replacement therapy consisted of a fixed dose of oral estradiol valerate, 6 mg daily, and intramuscular progesterone in oil, 100 mg daily. Estrogen and progesterone were continued for 10 more weeks after embryo transfer if pregnancy was established. After 13 embryo transfers, 8 pregnancies were obtained, for a pregnancy rate per transfer of 61.5%. Today seven pregnancies are progressing normally, including one set of twins. This results suggest that an oocyte donation program using a fixed and simple hormonal replacement therapy is an adequate treatment for these infertile couples.

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