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The giant gypsum crystals of Naica cave have fascinated scientists since their discovery in 2000. Human activity has changed the microclimate inside the cave, making scientists wonder about the potential environmental impact on the crystals. Over the last 9 years, we have studied approximately 70 samples. This paper reports on the detailed chemical–structural characterization of the impurities present at the surface of these crystals and the experimental simulations of their potential deterioration patterns. Selected samples were studied by petrography, optical and electronic microscopy, and laboratory X-ray diffraction. 2D grazing incidence X-ray diffraction, X-ray μ-fluorescence, and X-ray μ-absorption near-edge structure were used to identify the impurities and their associated phases. These impurities were deposited during the latest stage of the gypsum crystal formation and have afterward evolved with the natural high humidity. The simulations of the behavior of the crystals in microclimatic chambers produced crystal dissolution by 1–4% weight fraction under high CO2 concentration and permanent fog, and gypsum phase dehydration under air and CO2 gaseous environment. Our work suggests that most surface impurities are of natural origin; the most significant anthropogenic damage on the crystals is the extraction of water from the caves.
The attention deficit hyperactivity disorder (ADHD) is a common neuropsychiatric disease in infancy and adolescence, its world prevalence in the general population is high 3.4%. There is genetic evidence that consistently supports the polygenic nature of ADHD with a heritability estimated between 75% and 91%; literature proposes that the brain derived neurotrophic factor (BDNF) is a candidate gene that participates in the ADHA pathogenesis. One of the most studied polymorphisms is the Val66Met. The aim of this study was to determine a family-based an association between the rs6265, rs122,733,63 and rs110,301,19 polymorphisms of the BDNF gene and the ADHD in a Mexican population. The ADHD diagnose was performed by a pedopsychiatrist utilizing the diagnostic and statistical manual of mental disorders (DSM-V) who selected 35 patients; along with the biological parents, a total of 105 individuals grouped in family-trios (mother, father and ADHD patient) were studied. Of the 35 probands, 32 were men and 3 were women (average age 7.7 years; age range 4–14 years). Subsequently, no statistically significant association was observed between the BDNF gene polymorphisms and the ADHD etiology in Mexican families: rs6265 (χ2 = 1.33; P = 0.24); rs122,733,63 (χ2 = 1.33; P = 0.24); rs110,301;19 (χ2 = 0.66; P = 0.41). Furthermore, no preference of transmission was observed for any of the haplotypes. In conclusion, it was not possible to prove any association between the BDNF gene polymorphic variants and ADHD in a Mexican population. Future studies comprising larger samples are necessary to determine the potential role of the BDNF gene in ADHD.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
The purpose of this paper is to describe the development and initial accomplishments of a training program of young leaders in community mental health research as part of a Latin American initiative known as RedeAmericas. RedeAmericas was one of five regional ‘Hubs’ funded by the National Institute of Mental Health (NIMH) to improve community mental health care and build mental health research capacity in low- and middle-income countries. It included investigators in six Latin American cities – Santiago, Chile; Medellín, Colombia; Rio de Janeiro, Brazil; and Córdoba, Neuquén, and Buenos Aires in Argentina – working together with a team affiliated with the Global Mental Health program at Columbia University in New York City. One component of RedeAmericas was a capacity-building effort that included an Awardee program for early career researchers in the mental health field. We review the aims of this component, how it developed, and what was learned that would be useful for future capacity-building efforts, and also comment on future prospects for maintaining this type of effort.
During the “DBS Canada Day” symposium held in Toronto July 4-5, 2014, the scientific committee invited experts to share their knowledge regarding deep brain stimulation (DBS) management of movement disorders in three domains: (1) the programming algorithms, (2) the necessary team to run a neurosurgery program, and (3) the appropriate scales to better define in a more comprehensive fashion the effect of the brain surgery. Each presentation was followed by an open discussion, and this article reports on the conclusions of this meeting on these three questions. Concerning programming, the role of the pulse width and the switching off of the stimulation at night for thalamic stimulation for the control of tremor have been discussed. The algorithms proposed in the literature for programming in Parkinson’s disease (PD) need validation. In dystonia, the use of monopolar vs bipolar parameters, the use of low vs high frequencies and the use of smaller versus larger pulse widths all need to be examined properly. Concerning the necessary team to run a neurosurgical program, recommendations will follow the suggestions for standardized outcome measures. Regarding the outcome measures for DBS in PD, investigations need to focus on the non-motor aspects of PD. Identifying which nonmotor symptoms respond to DBS would allow a better screening before and satisfaction postoperatively. There is an important need for more data to determine the optimal programming protocol and the standard measures that should be performed routinely by all centers.
The study of corrosion behavior of polyurethane/nanohydroxyapatite hybrid coating in aerated Hank solution at 25 °C by Potentiodinamic and Electrochemical Impedance techniques was realized. The nanohydroxyapatite (nHA) powders were synthesized by ultrasonic assisted co-precipitation wet chemical method and then mixed with pure polyurethane (PU) during the polymerization. Results were supported by SEM morphologic characterization. Results showed that good corrosion resistance of hybrid coating, showing small corrosion product layer formation. Corrosion mechanisms are affected by an increasing of polarization resistance, promoting decreasing in the corrosion rates. Diffusion of ionic species was the governing mechanism in the corrosion behavior of polyurethane/nanohydroxyapatite hybrid coating.
Blood vessel expansion and reduction in the corpus luteum (CL) is regulated by the vascular endothelial growth factor (VEGF) system and linked to the maintenance of the CL. The VEGF system has both angiogenic and antiangiogenic ligands and receptors. Our objective was to evaluate the relationship between the mRNA expression of angiogenic and antiangiogenic members of the VEGF system in the CL, throughout the luteal phase of the oestrous cycle in cows. The CL of 18 cows were collected by transvaginal surgery on days 4, 6, 9, 12, 15 and 18 of the oestrous cycle and the mRNA expression of VEGF system components was evaluated by quantitative real-time PCR. The mRNA expression of VEGF ligands and receptors increased (P<0.05) from the early- and mid-luteal phase (days 4 to 12) reaching its maximum expression on day 15 of the cycle. We found no expression of VEGF164b throughout the cycle. Expression of sVEGFR1 did not change during the oestrous cycle and exceeded that of the VEGFR1 by 100 times. Nonetheless, as VEGFR1 increased, the relationship between the soluble and membrane receptor decreased (P<0.01). In contrast, the expression of VEGFR2 was higher than that of its soluble isoform for all days studied, however, the ratio between the membrane-bound and its soluble counterpart decreased continuously throughout the cycle (P<0.01). Our results show that the expression levels for VEGF ligands, receptors and their antagonistic counterparts are adjusted during CL development and regression, to upregulate angiogenesis early in the oestrous cycle and restrict it at the time of luteolysis.
We present the very first detection of N2H+J = (1 – 0) and CH3OH(2k−1k) line emission on 5″ scales in the circumnuclear disk (CND) around Sgr A*. The emission matches the position and shape of the dark clouds in the near-infrared. Our findings suggest that these molecular clouds in the eastern CND are significantly colder and denser than the rest of the CND, and partially shocked. The research on these dark clouds will contribute to understanding the processes of star formation close to a supermassive black hole.
A fast moving infrared excess source (G2) which is widely interpreted as a core-less gas and dust cloud approaches Sagittarius A* (Sgr A*) on a presumably elliptical orbit. VLT Ks-band and Keck K′-band data result in clear continuum identifications and proper motions of this ∼19m Dusty S-cluster Object (DSO). In 2002-2007 it is confused with the star S63, but free of confusion again since 2007. Its near-infrared (NIR) colors and a comparison to other sources in the field speak in favor of the DSO being an IR excess star with photospheric continuum emission at 2 microns than a core-less gas and dust cloud. We also find very compact L′-band emission (<0.1″) contrasted by the reported extended (0.03″ up to ∼0.2″ for the tail) Brγ emission. The presence of a star will change the expected accretion phenomena, since a stellar Roche lobe may retain a fraction of the material during and after the peri-bothron passage.
The design and construction of an instrumentation for NOX degradation in a dielectric-barrier discharge reactor (DBDR) is presented. This is endowed with a parallel plane electrode glass-glass (GG) circular geometry configuration. A solid-state multi-cellular power supply was produced in order to generate the plasma discharge. The power supply is based on a full-bridge voltage inverter commanded by three 4.33 kHz square-wave signals. Thus, the output converter signal is filtered by a resonant LC circuit, providing a 13 kHz sine wave to the DBDR. Initial results showing high removal efficiencies of about 97% have been obtained by means of this instrumentation.
A dielectric barrier discharge (DBD) has been successfully applied to studying, both theoretically and experimentally, phenol degradation in waste water aqueous solutions. A coaxial reactor was selected where the liquid waste constitutes a part of the internal electrode itself, the liquid solution flowing up inside the hollow internal electrode impelled by a submersible pump. Thus, the solution falls by gravity on the external surface of the internal electrode. The DBD gas flows in parallel to the surface of the liquid. The cold plasma was generated from Ar-O2 mixture and O2 pure with the inclusion of moisture from the same solution. Two power supplies were compared delivering potentials up to 23 kV at 1.5 kHz, and up to 12 kV at 15.6 kHz respectively. The initial concentration of phenol was around 5 × 10−3 mol/L and efficiencies up to 99% were obtained after 1 h of treatment. Finally, a simplified kinetics model was developed where the temporal evolution of the compounds generated in the phenol degradation process was analyzed. Hydroquinone, catechol and resorcinol were obtained as byproducts and H2O, CO2 and some light carboxylic acids as final products.
High levels of alexithymia as well as low scores on assertiveness have been described in patients with chronic pain and headache.
To determine alexithymia and assertiveness scores and to explore their association with headache impact, in primary chronic headache patients.
This study aims to advance knowledge of the emotional expressiveness in headache impact.
In a sample of 62 outpatients, we used the Toronto Alexithymia Scale (TAS-20), the Rathus Assertiveness Scale and the Headache Impact Test (HIT-6) and applied the Pearson correlation index.
77.4% of women, 36.3 years mean age. The most prevalent diagnoses are migraine combined with tension type headache (33.9%), migraine alone (32.3%) and tension-type headache alone (22.6%). Most of the patients have not any psychiatric comorbidity (77.8%). We observe a direct linear relationship and statistically significant difference, between the total impact of headache and the total score of alexithymia (r = 0.27 p = 0.03) and there is an inverse correlation between the impact of headache and the total score of the scale of assertiveness, not statistically significant (r = −0.004 p = 0.97).
Discriminated by diagnostic groups, we found that the association between assertiveness and headache impact remains only in patients with migraine alone, while that between alexithymia and headache impact is preserved in all subgroups.
Two indirect measures of the difficulties in emotional expressiveness such as alexithymia and assertiveness, show the expected association with headache impact. The sample size can influence some of the correlations not statistically significant.
Tree species are potential hosts for epiphytes; however in some forests epiphytes have a biased distribution among hosts. In a tropical dry forest of Mexico, previous research showed that there are trees with few epiphytes. It is possible that the bark of these hosts contain allelochemicals that influence epiphyte seed germination. The aims of this study were (1) to determine whether hosts with low epiphyte abundance (Ipomoea murucoides, I. pauciflora and Lysiloma acapulcense) would inhibit seed germination of Tillandsia recurvata through aqueous and organic bark extracts, (2) to determine whether germination of T. recurvata would differ among the hosts with low epiphyte abundance and a host with high epiphyte abundance (Bursera copallifera) and (3) to relate the chemical composition of organic bark extracts with inhibition of T. recurvata seed germination. Hexanic and dichloromethanic extracts were partially chemically characterized. Total phenolics and flavonoids concentrations of methanolic extracts were analysed. Aqueous and organic bark extracts from hosts with few epiphytes inhibited T. recurvata seed germination. Aqueous and dichloromethanic extracts of B. copallifera inhibited slightly the germination of T. recurvata. There was a positive correlation between concentration of flavonoids and inhibition of seed germination. Results suggest that a combination of compounds may be responsible for affecting the germination of T. recurvata. This study demonstrates the chemical effect of aqueous and organic bark extracts from hosts on germination of an epiphytic bromeliad.
Microplasmas are nowadays a powerful tool with multiple
practical applications. The performance of a specific instrumentation for a
plasma needle capable of producing non-thermal plasmas and a DBD reactor
able to produce atmospheric pressure plasmas, both of them designed and
already constructed, is reported. These devices operate at 13.56 MHz and are
driven by a specifically built radio frequency (RF) resonant converter. The
reactors, which operate at atmospheric pressure in a He-air gas mixture at a
1.5 SLPM flow, have been successfully applied to eliminate E. coli bacteria. In the
needle case, bacterial samples were submitted typically to a 500 V peak
voltage plasma discharge for 120 s. In the DBD treatment, the samples were
processed with typical 750 V peak voltage plasma discharges for 80 s. The
sample pH was used as a criterion to measure the effectiveness of the plasma
treatment, in such a way that the return to the basal pH value after the
treatment can be assumed as the validation of the complete bacterial
In response to the Latin American cholera epidemic, El Salvador began a prevention programme in April 1991. The first case was confirmed in August, and 700 cases were reported within 3 months. A matched case-control study was conducted in rural La Libertad Department in November 1991. Illness was associated with eating cold cooked or raw seafood (odds ratio [OR] = 7·0; 95% confidence limits [CL] = 1·4, 35·0) and with drinking water outside the home (OR = 8·8; 95% CL = 1·7, 44·6). Assertion of knowledge about how to prevent cholera (OR = 0·2; 95% CL = 0·1, 0·8) and eating rice (OR = 0·2; 95% CL = 0·1, 0·8) were protective. More controls than patients regularly used soap (OR = 0·3; 95% CL = 0·1, 1·0). This study demonstrated three important points for cholera prevention: (1) seafood should be eaten cooked and hot; (2) populations at risk should be taught to treat household drinking water and to avoid drinking water outside the home unless it is known to be treated; and (3) education about hygiene can be an important tool in preventing cholera.
A new paleolimnological dataset from Lake Pacucha (13 °S, 3095 m elevation) in the Peruvian Andes provides evidence of changes in lake level over the past 24,700 yr. A late-glacial highstand in lake level gave way to an early-Holocene lowstand. This transition appears to have paralleled precessional changes that would have reduced insolation during the wet-season. The occurrence of benthic/salt-tolerant diatoms and CaCO3 deposition suggest that the lake had lost much of its volume by c. 10,000 cal yr BP. Pronounced Holocene oscillations in lake level included a second phase of low lake level and heightened volatility lasting from c. 8300 to 5000 cal yr BP. While a polymictic lake formed at c. 5000 cal yr BP. These relatively wet conditions were interrupted by a series of drier events, the most pronounced of which occurred at c. 750 cal yr BP. Paleolimnological changes in the Holocene were more rapid than those of either the last glacial maximum or the deglacial period.