Actividades tecnológicas articuladoras: una interpretación fértil del paisaje desértico costero de Arica (Chile)

This is the final version. Available from the Universidad Nacional de La Plata via the DOI in this record. El siguiente trabajo propone que la tecnología en fibra vegetal fue un eje articulador de decisiones sociales y tecnológicas ejecutadas por grupos de Cazadores-Recolectores y Pescadores tempranos de Arica (CRP). Esto en el marco de los procesos tecnológicos desplegados para la manufactura de artefactos sobre esta materia prima entre ca. 10000-3700 AP. Para concretar la propuesta se efectuó un análisis de los atributos técnicos-textiles de artefactos en materia vegetal provenientes de sitios de la costa ariqueña, un registro actualísitco de artesanías en materias vegetales que incluyó la identificación de etapas de manufactura y un mapeo de la cubierta vegetacional mediante teledetección. Lo anterior se sustenta teóricamente mediante el uso operacionalizado del concepto taskscape, nutrido con nociones sociales de tecnología y con el modelo de chaîne opératoire para así integrar a esta tecnología en el escenario social. Como conclusión, se logra definir que la manufactura fue parte del orden cotidiano de estos grupos que tras habitar continuamente estuarios y humedales transformaron de manera constante el entorno natural/cultural. Por ende, la extracción-selección, procesamiento y tejido conforma solo una fracción de una actividad social relevante que permite comprender aspectos sociales y tecnológicos que van más allá de la mirada del fitness alimenticio.FONDECY

Scaling laws in the diffusion limited aggregation of persistent random walkers

We investigate the diffusion limited aggregation of particles executing persistent random walks. The scaling properties of both random walks and large aggregates are presented. The aggregates exhibit a crossover between ballistic and diffusion limited aggregation models. A non-trivial scaling relation $\xi\sim\ell^{1.25}$ between the characteristic size $\xi$, in which the cluster undergoes a morphological transition, and the persistence length $\ell$, between ballistic and diffusive regimes of the random walk, is observed.Comment: 13 pages, 7 figures; Physica A: Statistical Mechanics and its Applications, In Press, Uncorrected Proof, Available online 8 July 2011, ISSN 0378-437

Antimicrobial effect of vancomycin electro-transferred water against methicillin-resistant Staphylococcus aureus

Background: There is a number of alternative and complementary therapeutics that are unproven or have not been properly tested. For past twenty years, the transfer of bio-energetic information has been recognized as a novel scientific approach capable of contributing to improved therapy in the management of several diseases through the so-called bio-resonance therapy (BRT). Although BRT was discovered in the late 1980s, it is still poorly studied. The aim of this study was to evaluate the antibacterial effect of water samples transferred with electronic information of vancomycin, a well known drug against methicillin-resistant Staphylococcus aureus (MRSA), by using a BRT device on bacterial cultures.Material and Methods: MRSA cultures were treated with vancomycin electro-transferred water samples, vancomycin (4.0 and 8.0 μg/mL), sham electro-transferred (water to water) and non-transferred water samples (medium alone). Growth inhibition was evaluated in liquid and solid culture medium, spectrophotometrically and by CFU determination respectively.Results: The obtained data showed that by transferring vancomycin (4.0 and 8.0 μg/mL) information to water samples, the growth of cultured MRSA was significantly (p< 0.05) inhibited (up to 35%), compared with those cultures treated with electro-transferred water to water or cultured in medium alone (0% growth inhibition).Conclusion: This in vitro study suggests that water samples that are electronically transferred with vibration sustained information of vancomycin are capable of inhibiting growth of axenically cultured methicillin resistant S. aureus.Key words: Antimicrobial effect, electro-transferred water, bio-resonance, vancomycin, Sthaphylococcus aureus

Anti-giardia activity of hexane extract of Citrus aurantifolia (Christim) swingle and some of its constituents

Background: Giardia lamblia is a parasite that causes giardiasis in humans and other mammals. The common treatment includes different drugs, which were described to produce unpleasant side effects. Citrus aurantifolia, popularly known as “lima”, is a plant used in traditional medicine to treat gastrointestinal symptoms. The aim of the present study was to evaluate the anti-Giardia activity of 10 pure compounds obtained from a hexanic extract of Mexican lime on the basis of trophozoite growth inhibition.Materials and Methods: A hexanic extract obtained from fresh fruit peels of Citrus aurantifolia was tested on G. lamblia strain 0989:IMSS trophozoites cultured in TYI-S-33 medium. The concentration of all standard drugs, analyzed by gas chromatography, was adjusted at 10 mg/mL. Metronidazole was used as a positive control. Growth inhibition was determined by counting the number of trophozoites using a Neubauer chamber. The 50% inhibitory concentration (IC50) of each drug was calculated by probit analysis and 95% confidence limits were calculated.Results: 4-hexen-3-one, citral and geraniol showed IC50 values of 34.2, 64.5 and 229.49 μg/ml in axenic cultures after 24 hr of incubation, respectively. When these results were compared with a positive control of metronidazole; 4-hexen-3-one was 66 times; citral was 112 and geraniol was 441 times less active respectively. The other tested compounds did not inhibit the growth of cultured G. lamblia trophozoites.Conclusion: The obtained results lead us to propose that these tested compounds from C. aurantifolia have potential for use as therapeutic agents against giardiasis.Keywords: antigiardial ; Citrus aurantifolia; antiprotozoal activity; Giardia lambli

Internet Gaming Disorder treatment: a case study evaluation of four different types of adolescent problematic gamers

Research examining Internet Gaming Disorder (IGD) has grown markedly in recent years. However, research on its psychological treatment is still scarce, especially with respect to efficacy of specific programs. The PIPATIC (Programa Individualizado Psicoterapéutico para la Adicción a las Tecnologías de la Información y la Comunicación) program is a 22-session specialized treatment for adolescents with IGD. The present paper briefly outlines the cases of four treatment-seeking male adolescents aged between 13 and 18 years with different clinical IGD profiles undergoing the treatment. A case study using an A-B-A’ withdrawal design was conducted. After completing the PIPATIC program, all participants showed clinical improvement in the amount of time spent using video games and in the symptoms of IGD. Results also demonstrated they received lower scores on clinical tests related to comorbid disorders. In an area with so few studies relating to IGD treatment, the present study is of existential value and contributes clinical information concerning the treatment of IGD in treatment-seeking adolescent patients

Diets containing sea cucumber (Isostichopus badionotus) meals are hypocholesterolemic in young rats

Peer reviewedPublisher PD

Radio Emission from Ultra-Cool Dwarfs

The 2001 discovery of radio emission from ultra-cool dwarfs (UCDs), the very low-mass stars and brown dwarfs with spectral types of ~M7 and later, revealed that these objects can generate and dissipate powerful magnetic fields. Radio observations provide unparalleled insight into UCD magnetism: detections extend to brown dwarfs with temperatures <1000 K, where no other observational probes are effective. The data reveal that UCDs can generate strong (kG) fields, sometimes with a stable dipolar structure; that they can produce and retain nonthermal plasmas with electron acceleration extending to MeV energies; and that they can drive auroral current systems resulting in significant atmospheric energy deposition and powerful, coherent radio bursts. Still to be understood are the underlying dynamo processes, the precise means by which particles are accelerated around these objects, the observed diversity of magnetic phenomenologies, and how all of these factors change as the mass of the central object approaches that of Jupiter. The answers to these questions are doubly important because UCDs are both potential exoplanet hosts, as in the TRAPPIST-1 system, and analogues of extrasolar giant planets themselves.Comment: 19 pages; submitted chapter to the Handbook of Exoplanets, eds. Hans J. Deeg and Juan Antonio Belmonte (Springer-Verlag

The dynamics and star-forming potential of the massive Galactic centre cloud G0.253+0.016

Context: The massive infrared dark cloud G0.253+0.016 projected ~45 pc from the Galactic centre contains ~105 M⊙ of dense gas whilst being mostly devoid of observed star-formation tracers. Aims: Our goals are therefore to scrutinise the physical properties, dynamics and structure of this cloud with reference to its star-forming potential. Methods: We have carried out a concerted SMA and IRAM 30 m study of this enigmatic cloud in dust continuum, CO isotopologues, several shock tracing molecules, as well as H2CO to trace the gas temperature. In addition, we include ancillary far-IR and sub-mm Herschel and SCUBA data in our analysis. Results: We detect and characterise a total of 36 dust cores within G0.253+0.016 at 1.3 mm and 1.37 mm, with masses between 25 and approximately 250 M⊙, and find that the kinetic temperature of the gas traced by H2CO ratios is >320 K on size-scales of ~0.15 pc. Analysis of the position–velocity diagrams of our observed lines shows broad linewidths and strong shock emission in the south of the cloud, indicating that G0.253+0.016 is colliding with another cloud at vLSR ~ 70 km s-1. We confirm via an analysis of the observed dynamics in the Central Molecular Zone that it is an elongated structure, orientated with Sgr B2 closer to the Sun than Sgr A*, however our results suggest that the actual geometry may be more complex than an elliptical ring. We find that the column density probability distribution function of G0.253+0.016 derived from SMA and SCUBA dust continuum emission is log-normal with no discernible power-law tail, consistent with little star formation, and that its width can be explained in the framework of theory predicting the density structure of clouds created by supersonic, magnetised turbulence. We also present the Δ-variance spectrum of this region, a proxy for the density power spectrum of the cloud, and show it is consistent with that expected for clouds with no current star formation. Finally, we show that even after determining a scaled column density threshold for star formation by incorporating the effects of the increased turbulence in the cloud, we would still expect ten stars with masses >15 M⊙ to form in G0.253+0.016. If these cannot be accounted for by new radio continuum observations, then further physical aspects may be important, such as the background column density level, which would turn an absolute column density threshold for star formation into a critical over-density. Conclusions: We conclude that G0.253+0.016 contains high-temperatures and wide-spread shocks, displaying evidence of interaction with a nearby cloud which we identify at vLSR ~ 70 km s-1. Our analysis of the structure of the cloud can be well-explained by theory of magnetised turbulence, and is consistent with little or no current star formation. Using G0.253+0.016 as a test-bed of the conditions required for star formation in a different physical environment to that of nearby clouds, we also conclude that there is not one column density threshold for star formation, but instead this value is dependant on the local physical conditions

Novel mutations in the voltage-gated sodium channel of pyrethroid-resistant Varroa destructor populations from the Southeastern USA

The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V) of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes