Scaling Analysis of an Image Encryption Scheme Based on Chaotic Dynamical Systems.

Despite that many image encryption systems based on chaotic or hyperchaotic systems have been proposed to protect different kinds of information, it has been crucial to achieve as much security as possible in such systems. In this sense, we numerically implement a known image encryption system with some variants, making special emphasis when two operations are considered in the scrambling stage. The variants of such an encryption system are based on some hyperchaotic systems, which generated some substitution boxes and the keys of the system. With the aim to have a more complete evaluation, some internal stages of the image encryption scheme have been evaluated by using common statistical tests, and also the scaling behavior of the encrypted images has been calculated by means of a two-dimensional detrended fluctuation analysis (2D-DFA). Our results show that the image encryption systems that include two operations or transformations in the scrambling stage present a better performance than those encryption systems that consider just one operation. In fact, the 2D-DFA approach was more sensitive than some common statistical tests to determine more clearly the impact of multiple operations in the scrambling process, confirming that this scaling method can be used as a perceptual security metric, and it may contribute to having better image encryption systems.

Ophthalmological changes of the posterior segment in patients with testicular cancer in a mixed-race population of the General Hospital of Mexico. / Alteraciones oftalmológicas del segmento posterior en pacientes con cáncer testicular en población latino-mestiza del Hospital General de México.

INTRODUCTION: The curing of a testicular tumour is currently feasible in more than 95% of patients, and in 80% of those with metastases. Until now, there has been no study or series of cases that describe the ocular changes of the posterior segment associated with testicular cancer. OBJECTIVE: To evaluate patients with a diagnosis of testicular cancer in order to determine the presence of changes in the posterior segment and the relationship to the stage. MATERIAL AND METHOD: An observational, cross-sectional, and descriptive study was conducted on 21 male patients (42 eyes) with a diagnosis of testicular cancer. Age, histological type, time of evolution, stage, treatment, and comorbidities were recorded, as well as visual acuity measurement (LogMAR), biomicroscopy of the anterior segment, and photographic records of the posterior pole and peripheral retina. RESULTS: The mean age was 29 years (18-43 years). All (100%) of the patients were treated surgically. The most frequent histological type was classic seminoma (42.8%), followed by the mixed germinal tumour (38.0%). At the time of evaluation, 42.8% of patients had a stage II, and 23.8% had distant metastasis. The changes in the posterior segment were: vascular tortuosity (14.2%), retinopathy associated with cancer (9.5%), choroidal metastasis (9.5%), pigmentary changes of the retinal pigment epithelium (9.5%), and retinal metastasis (4.7%). CONCLUSIONS: It is possible to find changes at the level of retinal pigment epithelium, as well as vascular tortuosity, retinopathy associated with cancer, and choroidal and/or retina metastases.

Annual variations in sexual hormones and births' frequency in female stump-tailed macaques (Macaca arctoides).

Although the breeding seasonality in Macaca arctoides have been studied over a long period of time, it is still controversial whether reproduction in this primate tend to increase during certain months of the year as it happens in most of the macaque species. Many authors have classified Macaca arctoides as not being seasonal species. Nonetheless, there were no reports, about seasonal variations of female sexual hormones to demonstrate that asseveration. Therefore, in the present study we collect 1611 fecal samples from June 2009 to November 2010 from 10 female stump-tailed macaques to measure 17ß-estradiol and progesterone concentrations. Also, we included the birth frequency per year, in order to identify if sexual hormones peaked at a certain period of the year, thus, births would be occurring six months later according to the gestation length of stump-tailed macaques. Our results indicate two mating seasons per year in stump-tailed macaques: one in July-August and a second one in November. The distribution of the birth frequency, throughout the year support these results. We conclude that stump-tail macaques have a discrete seasonality no different than most of macaques' species.

The invasive potential of Giardia intestinalis in an in vivo model.

Giardiasis is a neglected parasitic disease that affects primarily children, in whom it delays physical and mental development. The pathophysiology of giardiasis in not well understood, and most reports have identified Giardia intestinalis trophozoites only in the lumen and on the brush border of the small intestine. We identified Giardia trophozoites within the epithelium of the small intestine of a lactose intolerance patient. The Giardia trophozoites were obtained and cultured in vitro. In addition, we demonstrated Giardia trophozoite invasion in an animal model. Giardia trophozoites invaded the intestinal mucosa and submucosa of infected gerbils. The invasive trophozoites were observed at 21, 30 and 60 days age, and the average numbers of invaded sites were 17 ± 5, 15 ± 4, and 9 ± 3, respectively. We found trophozoites between epithelial cells, at the base of empty goblet cells, in lacteal vessels and within the submucosa. The morphological integrity of the invasive trophozoites was demonstrated via electron microscopy. The analysis of the gerbils infected with the trophozoites of the WB reference strain did not show intraepithelial trophozoites. These results demonstrate another Giardia pathogenic mechanism, opening the door to numerous future studies.

Three-dimensional structure and molecular dynamics studies of prorrenin/renin receptor: description of the active site.

The recent finding of a specific receptor for prorrenin/renin (PRR) has brought new insights into the physiology of the renin-angiotensin-aldosterone system. No undoubtable role has been described for this receptor so far. Its role seems to be important in chronic illnesses such as hypertension, possibly participating in the cardiovascular remodeling process, and diabetes where participation in inflammation development has been described. It is not possible, however, to explore the PRR function using classical pharmacological approaches due to the lack of specific agonists or antagonists. Two synthetic peptides have been described to accomplish these roles, but no conclusive data have been provided. There are no X-ray crystallography studies available to describe the structure and potential sites for drug development. So, the aim of this work was to model and theoretically describe the PRR. We describe and characterize the whole receptor protein, its spatial conformation and the potential interactions of PRR with the synthetic peptides available, describing the amino acid residues responsible for these interactions. This information provides the basis for directed development of drugs, seeking to agonize or antagonize PRR activity and study its function in health and ill stages.

Targeting a cluster of arginine residues of neuraminidase to avoid oseltamivir resistance in influenza A (H1N1): a theoretical study.

Following the influenza A (H1N1) pandemic in Mexico and around the world in 2009, the numbers of oseltamivir-resistant clinical cases have increased through a mechanism that remains unclear. In this work, we focus on studying the mutated NA structures ADA71175 (GenBank) and 3CKZ (PDB ID). Recently crystallized NA (PDB ID: 3NSS) was used as a wild-type structure and template to construct the three-dimensional (3D) structure of ADA71175. Then, the NA mutants and 3NSS natives as well as their refined monomer structures as determined through MD simulations (snapshots at 50 ns) were used as models to perform a docking study using a set of aryl-oseltamivir derivatives. These aryl-oseltamivir derivatives have better recognition properties than oseltamivir because of cation-π interactions with a cluster of Arg residues (118, 292, and 371) at the binding site. This cluster of Arg residues represents a potential binding site for aryl-oseltamivir derivatives that are potentially new NA inhibitors.

Attitude and knowledge of hearing loss among medical doctors selected to initiate a residency in Mexico.

Early diagnosis and intervention of hearing loss are directly influenced by the knowledge and attitude towards this condition among medical personnel, particularly in countries where screening is not performed routinely. The objective of this paper was to evaluate the attitude and knowledge of hearing loss in a group of physicians. A questionnaire with five Likert-type items and five multiple choice and fill-in-the-blank items was completed by 2727 physicians selected to start a medical residency. Results suggested that physicians' knowledge level on the matter is deficient and their attitude is far from the ideal; however, physicians selected for a residency in audiology showed slightly better results.

Effects of policosanol on postmenopausal women with type II hypercholesterolemia.

This randomized, double-blind, placebo-controlled study was conducted to investigate the efficacy, safety and tolerability of policosanol, a cholesterol-lowering drug purified from sugar-cane wax, in postmenopausal women with type II hypercholesterolemia. A total of 244 women who had experienced the menopause and showed elevated serum total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels despite 6 weeks on a standard lipid-lowering diet were randomized to receive placebo or policosanol 5 mg/day for 12 weeks, after which the dose was doubled to 10 mg/day for the next 12 weeks. Policosanol (5 and 10 mg/day) significantly lowered LDL-C levels (17.7% and 25.2%, respectively) and total cholesterol (12.6% and 16.7%, respectively), as well as the ratios of LDL-C to high-density lipoprotein cholesterol (HDL-C) (17.0% and 29.3%, respectively) and total cholesterol to HDL-C (16.7% and 27.2%, respectively), compared to the baseline and placebo; at the same time, policosanol significantly raised HDL-C levels by 16.5% and 29.3%, respectively. The drug was safe and well tolerated. No drug-related adverse events were observed, and even the extent of adverse events was less in the policosanol group than in the placebo group. Four serious adverse events occurred in the placebo group (one myocardial infarction, two cases of hypertensive status and one surgical intervention) compared to none in the policosanol group. In conclusion, policosanol is effective, safe and well tolerated in hypercholesterolemic postmenopausal women.

[Women and health professions in Puerto Rico: 1990]. / La mujer en las profesiones de la salud en Puerto Rico: 1990.

The main aim of the present study was to analyse the sex distribución for the health related professions in Puerto Rico. This was a descriptive investigation. The data was obtained from the Census of Population and Housing of Puerto Rico, 1990 and the fifth register of health professionals, 1989-92 from the Health Department of Puerto Rico. It was observed that women in the 90's are still participating, in the health professions, in occupations traditionally of their gender. Nevertheless, it has been observed an increased in the women's participation in those occupations usually performed by men such as: veterinary and podiatry. Women tend to be employed more frequently by the government. Men, on the other hand, are concentrated on those occupations with the highest prestige and status, in the health professions. In addition, a high proportion of men are employed on their own. In terms of income, women earn less income than men for almost all the health occupations taken into account.

Diseño de evaluación integral del Proyecto de Educación Intercultural Bilingue de Bolivia (PEIB) / Desing of integral evaluation of the project of education bilingual intercultural of Bolivia PEIB

Se concibe a la educación intercultural bilingue como instrumento estratégico que permita la consolidación y desarrollo de las nacionalidades indígenas bolivianas, su desarrollo armónico y su interacción con los otros grupos históricos sociales en oportunidades, condiciones y posibilidades de intercambio e interacción cada vez mejores. Desde esta perspectiva, la implementación del EIB en el país deberá contribuir a hacer posible el diálogo intercultural e interétnico, desde una perspectiva de relación horizontal y desprejuiciada. Ello implica que también en lo social, el modelo debe coadyuvar a la formación de un bilinguismo igualmente equilibrado de vernácula y castellano, a fin de superar la situación de diglosia que ahora caracteríza a la sociedad boliviana. Para que tales objetivos puedan ser logrados a plenitud, esta primera etapa en la que EIB atiende únicamente a población rural vernáculo hablante deberá posteriormente complementarse con otra en la cual, tal vez desde una modalidad diferente, la escuela urbana se convierta también en intercultural y bilingue, dando paso en los currículos a las lenguas indígenas y a los elementos culturales pertenecientes a los horizontes culturales. Sólo así se podrá avizorar la conformación de una identidad nacional

Diseño de evaluación integral del Proyecto de Educación Intercultural Bilingue de Bolivia (PEIB) / Desing of integral evaluation of the project of education bilingual intercultural of Bolivia PEIB

Se concibe a la educación intercultural bilingue como instrumento estratégico que permita la consolidación y desarrollo de las nacionalidades indígenas bolivianas, su desarrollo armónico y su interacción con los otros grupos históricos sociales en oportunidades, condiciones y posibilidades de intercambio e interacción cada vez mejores. Desde esta perspectiva, la implementación del EIB en el país deberá contribuir a hacer posible el diálogo intercultural e interétnico, desde una perspectiva de relación horizontal y desprejuiciada. Ello implica que también en lo social, el modelo debe coadyuvar a la formación de un bilinguismo igualmente equilibrado de vernácula y castellano, a fin de superar la situación de diglosia que ahora caracteríza a la sociedad boliviana. Para que tales objetivos puedan ser logrados a plenitud, esta primera etapa en la que EIB atiende únicamente a población rural vernáculo hablante deberá posteriormente complementarse con otra en la cual, tal vez desde una modalidad diferente, la escuela urbana se convierta también en intercultural y bilingue, dando paso en los currículos a las lenguas indígenas y a los elementos culturales pertenecientes a los horizontes culturales. Sólo así se podrá avizorar la conformación de una identidad nacional