Search

Abstract We report on the thermal neutron flux measurements carried out at the Laboratorio Subterráneo de Canfranc (LSC) with two commercial $$2^{\prime \prime } \times 2^{\prime \prime }$$ 2 ″ × 2 ″ CLYC detectors. The measurements were performed as part of an experimental campaign at LSC with $$^{3}$$ 3 He detectors, for establishing the sensitivity limits and use of CLYCs in low background conditions. A careful characterization of the intrinsic $$\alpha $$ α and $$\gamma $$ γ -ray background in the detectors was required and done with dedicated measurements. It was found that the $$\alpha $$ α activities in the two CLYC crystals differ by a factor of three, and the use of Monte Carlo simulations and a Bayesian unfolding method allowed us to determine the specific $$\alpha $$ α activities from the $$^{238}$$ 238 U and $$^{232}$$ 232 Th decay chains. The simulations and unfolding also revealed that the $$\gamma $$ γ -ray background registered in the detectors is dominated by the intrinsic activity of the components of the detector such as the aluminum housing and photo-multiplier and that the activity within the crystal is low in comparison. The data from the neutron flux measurements with the two detectors were analyzed with different methodologies: one based on an innovative $$\alpha $$ α /neutron pulse shape discrimination method and one based on the subtraction of the intrinsic $$\alpha $$ α background that masks the neutron signals in the region of interest. The neutron sensitivity of the CLYCs was calculated by Monte Carlo simulations with MCNP6 and GEANT4. The resulting thermal neutron fluxes are in good agreement with complementary flux measurement performed with $$^{3}$$ 3 He detectors, but close to the detection limit imposed by the intrinsic $$\alpha $$ α activity.

Abstract During the second long shutdown period of the CERN accelerator complex (LS2, 2019-2021), several upgrade activities took place at the n_TOF facility. The most important have been the replacement of the spallation target with a next generation nitrogen-cooled lead target. Additionally, a new experimental area, at a very short distance from the target assembly (the NEAR Station) was established. In this paper, the core commissioning actions of the new installations are described. The improvement in the n_TOF infrastructure was accompanied by several detector development projects. All these upgrade actions are discussed, focusing mostly on the future perspectives of the n_TOF facility. Furthermore, some indicative current and future measurements are briefly reported.

Transport networks in coastal, urban areas are extremely vulnerable to seismic events, with damage likely due to both ground motions and tsunami loading. Most existing models analyse the performance of structures under either earthquakes or tsunamis, as isolated events. This paper presents a numerical approach that captures the sequential earthquake–tsunami effects on transport infrastructure in a coastal area, taking into consideration the combined strains of the two events. Firstly, the dynamic cyclic loading is modelled, applied to the soil-structure system using a finite-difference approximation to determine the differential settlement, lateral displacement and liquefaction potential of the foundation. Next, using a finite-volume method approach, tsunami wave propagation and flooding potential are modelled. Finally, the hydrostatic and hydrodynamic loads corresponding to the wave elevation are applied to the post-earthquake state of the structure to obtain a second state of deformation. The sequential model is applied to an embankment in Manzanillo, Mexico, which is part of a main urban road; the response is analysed using ground motion records of the 1995 Manzanillo earthquake–tsunami event.

La alteración antrópica modifica el tipo de mamíferos que consumen frutos de Attalea butyracea en una selva neotropical y la intensidad con que lo hacen La pérdida del hábitat y la caza son dos de las principales causas de la disminución de mamíferos, que no solo afecta a la presencia de especies, sino también a sus funciones ecológicas. La frugivoría es una interacción clave en las zonas tropicales debido a que se halla muy extendida entre los mamíferos y los efectos que ejerce en la dinámica de la selva. Mediante la comparación de las visitas realizadas por mamíferos a la palma Attalea butyracea en dos sitios con grados bien diferenciados de alteración antrópica (con alteración y sin alteración) de la selva Lacandona, en el sureste de México, evaluamos cómo afecta la alteración antrópica a la interacción entre los mamíferos frugívoros y los frutos que se acumulan en el suelo de la selva. Usando cámaras trampa, registramos a los mamíferos que interactuaron con los frutos y estimamos la intensidad de la interacción. Registramos una mayor riqueza de especies de mamíferos frugívoros en el sitio sin alteración antrópica (nueve especies) que en el sitio con alteración (cuatro especies), donde no se registraron los mamíferos de mayor tamaño. Los mamíferos de talla grande mostraron una interacción más intensa con los frutos en cuanto a la frecuencia y la duración de sus visitas. Nuestro estudio hace hincapié en la necesidad de adoptar medidas de conservación que permitan asegurar la presencia de las especies en los sitios con alteración antrópica, así como sus interacciones bióticas.

Volcanic emissions are a source of halogens in the atmosphere. Rapid reactions convert the initially emitted hydrogen halides (HCl, HBr, and HI) into reactive species such as BrO, Br2, BrCl, ClO, OClO, and IO. The activation reaction mechanisms in the plume consume ozone (O3), which is entrained by ambient air that is mixed into the plume. In this study, we present observations of the oxidation of bromine, chlorine, and iodine during the first 11 min following emission, examining the plume from Santiago crater of the Masaya volcano in Nicaragua. Two field campaigns were conducted: one in July 2016 and one in September 2016. The sum of the reactive species of each halogen was determined by gas diffusion denuder sampling followed by gas chromatography–mass spectrometry (GC-MS) analysis, whereas the total halogens and sulfur concentrations were obtained by alkaline trap sampling with subsequent ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) measurements. Both ground and airborne sampling with an unoccupied aerial vehicle (carrying a denuder sampler in combination with an electrochemical SO2 sensor) were conducted at varying distances from the crater rim. The in situ measurements were accompanied by remote sensing observations (differential optical absorption spectroscopy; DOAS). The reactive fraction of bromine increased from 0.20 ± 0.13 at the crater rim to 0.76 ± 0.26 at 2.8 km downwind, whereas chlorine showed an increase in the reactive fraction from (2.7 ± 0.7) × 10−4 to (11 ± 3) × 10−4 in the first 750 m. Additionally, a reactive iodine fraction of 0.3 at the crater rim and 0.9 at 2.8 km downwind was measured. No significant change in BrO / SO2 molar ratios was observed with the estimated age of the observed plume ranging from 1.4 to 11.1 min. This study presents a large complementary data set of different halogen compounds at Masaya volcano that allowed for the quantification of reactive bromine in the plume of Masaya volcano at different plume ages. With the observed field data, a chemistry box model (Chemistry As A Boxmodel Application Module Efficiently Calculating the Chemistry of the Atmosphere; CAABA/MECCA) allowed us to reproduce the observed trend in the ratio of the reactive bromine to total bromine ratio. An observed contribution of BrO to the reactive bromine fraction of about 10 % was reproduced in the first few minutes of the model run.

Las redes de sensores inalámbricos disponen de un campo muy amplio de aplicaciones y aún muchos desafíos pendientes, especialmente aquellos relacionados con la evolución de la electrónica digital, ancho de banda, reducción de costos de implementación, cobertura de red y capacidad de procesamiento. Este documento propone una configuración de red inalámbrica multisalto orientada a instalaciones domóticas inteligentes, basadas en microcontroladores de 32 bits y módulos de comunicación inalámbrica de bajo costo, que permita tener cobertura completa entre los dispositivos del sistema domótico con una reducida pérdida de datos, mejora en la capacidad de procesamiento, adaptabilidad y escalabilidad en los nodos. La evaluación del desempeño de la red considera las siguientes métricas: tiempo de respuesta, alcance de red, escalabilidad y precisión. Los resultados experimentales determinaron una adaptación exitosa del protocolo multisalto AODV, permitiendo una cobertura suficiente para una vivienda unifamiliar, a una velocidad de transmisión de 250Kbps, que garantiza la integridad y seguridad de los datos.

This study proposes an image-based approach to evaluate the validity of numerical results for cases where the setup can be assumed to be two-dimensional (2D) and mixing between liquids of different densities occurs under a free-surface condition. The proposed methodology is based on the estimation of the relative errors of the model through density matrices generated from images of the experimental and numerical results (i.e., post-processing snapshots of the density field). To demonstrate the use of the methodology, experimental tests and numerical simulations were performed for a double-dam-break problem with two miscible liquids. For the experiments, a high-speed camera was employed to capture details of the fluid interactions after the dam breaking. For the numerical simulations, an OpenFOAM® multiphase solver was employed to reproduce the benchmarking tests. Three turbulence approaches were tested: a zero-equation RANS model, a two-equation (k-epsilon) RANS model, and a Large-Eddy Simulation (LES) model. The experimental results compared favorably against the numerical results, with averaged relative errors of ~17 and ~19 % for the zero-equation and the two-equation turbulence models, respectively, and ~14 % for the LES model. From the results obtained, it can be inferred that the two-equation (k-epsilon) model had limitations in reproducing the mixing between the liquid phases in terms of relative errors. The LES model reproduces the mixing between phases more accurately than zero and two-equation RANS models, which were seen to be more suitable for capturing the formation of large eddies in the initial phase of the experiment. The present methodology can be improved and extended for different multiphase flow configurations.

73Ge(n,γ) cross sections were measured at the neutron time-of-flight facility n_TOF at CERN up to neutron energies of 300 keV, providing for the first time experimental data above 8 keV. Results indicate that the stellar cross section at kT=30 keV is 1.5 to 1.7 times higher than most theoretical predictions. The new cross sections result in a substantial decrease of 73Ge produced in stars, which would explain the low isotopic abundance of 73Ge in the solar system. Keywords: Nucleosynthesis, Neutron capture, s process, Germanium, n_TOF

The neutron capture cross section of 154Gd was measured from 1 eV to 300 keV in the experimental area located 185 m from the CERN n_TOF neutron spallation source, using a metallic sample of gadolinium, enriched to 67% in 154Gd. The capture measurement, performed with four C6D6 scintillation detectors, has been complemented by a transmission measurement performed at the GELINA time-of-flight facility (JRC-Geel), thus minimising the uncertainty related to sample composition. An accurate Maxwellian averaged capture cross section (MACS) was deduced over the temperature range of interest for s process nucleosynthesis modelling. We report a value of 880(50) mb for the MACS at kT=30 keV, significantly lower compared to values available in literature. The new adopted 154Gd(n,γ) cross section reduces the discrepancy between observed and calculated solar s-only isotopic abundances predicted by s-process nucleosynthesis models. Keywords: s process, 154Gd, Neutron time of flight, n_TOF

This work reports on accurate, high-resolution measurements of the 25Mg(n,γ)26Mg and 25Mg(n,tot) cross sections in the neutron energy range from thermal to about 300 keV, leading to a significantly improved 25Mg(n,γ)26Mg parametrization. The relevant resonances for n+25Mg were characterized from a combined R-matrix analysis of the experimental data. This resulted in an unambiguous spin/parity assignment of the corresponding excited states in 26Mg. With this information experimental upper limits of the reaction rates for 22Ne(α,n)25Mg and 22Ne(α,γ)26Mg were established, potentially leading to a significantly higher (α,n)/(α,γ) ratio than previously evaluated. The impact of these results has been studied for stellar models in the mass range 2 to 25 M⊙.

Se realizó la dosimetría en campos de radiación de 60 Co y de 137 Cs, correspondientes al irradiador Gammabeam 651PT, recargado con nuevas barras de 60 Co y de un nuevo irradiador autoblindado Gammacell - 3000 Elan de 137 Cs qu e fue adquirido con fondos CONACYT. La radiación gamma de 60 Co del Gammabeam , se utiliza para esterilización de productos industriales y para investigación en cambios de propiedades químicas y físicas de muestras sólidas y acuosas , de interés en la Univers idad Nacional Autónoma de México (UNAM). Sin embargo, la diferencia de energía entre los fotones gamma del 60 Co (1.17, 1.33 MeV) y del 137 Cs (0.66 MeV) hace interesante s los cambios en las muestras de investigación , tales como polímeros, nuevos materiales dosimétricos, compuestos orgánicos, etc., que se investigan actualmente en el Instituto de Ciencias Nucleares de la UNAM. Para utilizar los campos de radiación de los irradiadores, es importante determinar las dosis de exposición. En este trabajo, se infor ma la metodología llevada a cabo para la dosimetría de las fuentes de radiación gamma usando el dosímetro químico de Fricke. En este, se lleva a cabo la reacción de oxidación en medio ácido del ion ferroso a férrico. Los resultados en el Gammabeam muestran distribuciones de razones de dosis menores a 99 Gy/min en su cámara de irradiación. En el caso del irradiador de 137 Cs se obtuvo la razón de dosis, 10.89 Gy/min, al centro de su cámara; los resultados obtenidos con la dosimetría realizada en nuestro labor atorio coincidieron satisfactoriamente con los certificados otorgados previamente por el proveedor del Gammacell - 3000. Dado que las fuentes no son puntuales en los irradiadores, se determinaron las incertidumbres asociadas a las dosis. Los dos irradiadores presentan razones de dosis adecuadas para continuar apoyando a la investigación científica y ofrecer también el servicio de irradiación a escala semi - industrial.

The use of body condition score (BCS), as a tool for monitoring the energy balance and body reserves of sheep, involves establishing the relationship between BCSC and body weight (BW). The objective of the study was to evaluate a prediction equation for BW of non-pregnant and non-lactating Pelibuey ewes, which was developed using a data set composed by 303 2-3-year-old, non-pregnant and non-lactating Pelibuey ewes with a mean BW of 44.71± 9.98 kg and BCS (BW= 22.47 + 6.90 * BCS). The evaluation of the equation was assessed with the Model Evaluation Systems using an independent data set of BW (37.38±7.71 kg), and BCS (2.2±1.10 units) obtained from 52 non-pregnant and non-lactating Pelibuey ewes. The linear regression analysis between BW values observed and predicted showed that the intercept did not differ from zero (0.311, P = 0.91) and the slope did not differ from one (0.984, P = 0.83). The model proved accurate, the point (0, 1) is within the ellipse; the point F was not significant (P = 0.3477). The equation presented a mean precision (R2 = 0.7924) and a good accuracy (bias correction factor, Cb = 0.99). The modeling efficiency (MEF = 0.7911) indicated a relatively high value of concordance between the observed and predicted values. The concordance correlation coefficient between both values was 0.89. The RMSEP (root mean square error prediction) accounted for 9.27% from BW observed. The predictive model presented a good precision and accuracy to estimate BW of non-pregnant and non-lactating Pelibuey ewes with PV ranges from 26.3 to 75.0 kg reared under production systems of the humid tropic. In addition, the model suggests that 6.90 ±0.32 kg of BW is required to increase BCS in one unit in this type of Pelibuey ewes.

Background: Cancer testis antigens (CTA) are expressed in several types of cancer but not in normal adult tissue, with the exception of testicular germ cells, and for this reason are considered targets for immunotherapy. Objective: The aim of this study was to determine the frequency and clinical significance of CTA expression in cells from patients with chronic myeloid leukaemia (CML). Materials and methods: We analysed 8 genes of the CTA family (MAGE-A3, MAGE-A4, MAGE-B2 MAGE-C1, BAGE-1, GAGE-2, LAGE-1 and NY-ESO-1) in 10 peripheral blood samples from healthy donors and 65 bone marrow samples from CML patients using reverse transcriptase polymerase chain reaction (RT-PCR). Eleven samples from hematopoietic progenitor stem cells from patients receiving conventional treatment (hydroxyurea and INFα) and 21 samples from patients receiving tyrosine kinase inhibitors (Imatinib, Nilotinib, Dasatinib) were analysed. Results: Frequency of CTA genes in CML patients was 32.3%, 63.0%, 1.5%, 3.0%, 6.1%, 20.0%, 13.8% and 36.9% for MAGE-A3, MAGE-A4, MAGE-B2, MAGE C1, BAGE, GAGE, LAGE and NY-ESO, respectively. The correlation between expression and clinical parameters showed statistical significance in the MAGE-A3 genes in sex (p = 0.018), MAGE-C1 in leukocytes (p = 0.014) in platelets (p = 0.002), and finally LAGE-1, which was associated with platelets (p = 0.001). The hematopoietic progenitor stem cells from patients in treatment showed a higher frequency of expression than de novo patients. In patients receiving conventional drugs (CD), frequency of MAGE-A3 expression was 50%, and 69.2% with TKI, MAGE-A4 frequency was 20% with CD and 53.8% with TKI. Finally, frequency of NY-ESO-1 was 20% with CD and 0% with TKI. The frequency of MAGE-A4 expression was highest, followed by MAGE-A3, NY-ESO-1, GAGE-2, LAGE-1, BAGE-1, MAGE-B2 and MAGE-C1. Conclusion: Detection of CTA genes by molecular biology techniques is important due to their use as biomarkers in LMC, in the monitoring of disease progression and in patients who are resistant to chemotherapy. The frequency of CTA expression in treated and de novo differs significantly.

Acute leukaemias are characterised by uncontrolled proliferation of immature blood cells with lymphoid or myeloid lineage. Morphological classification is based on the identification of the leukaemia cell line and its stage of differentiation. The first microscopic descriptions dating from the 1930s pointed to 2 different types of leukaemia cells: lymphoid and myeloid. In 1976, the consensus that led to the French-American-British (FAB) classification was achieved. This includes criteria for identifying myeloid and lymphoid leukaemias, and gives a list of morphological subtypes, describing how these affect the patient's prognosis. Today, despite new classifications based on sophisticated studies, FAB classification is widely used by experts due to its technical simplicity, good diagnostic reliability and cost-effectiveness.

Las aplicaciones de la nanotecnología (NT) en los sistemas agrícolas son diversas, ofreciendo el potencial para mejorar significativamente su productividad y eficiencia al reducir costos y cantidades de agroquímicos aplicados. Las nanopartículas (NPs) metálicas de óxido de zinc, cobre y fierro, ya sean puras o mezcladas con plata, están siendo estudiadas globalmente por su potencial agrícola como promotores de crecimiento, nanofertilizantes y antimicrobiales. Considerando lo antes señalado, el objetivo de este trabajo fue evaluar el efecto de NPs de óxido de zinc puras (NPsZnO) y con plata (NPsZnO+Ag) en el crecimiento de plantas de chile (Capsicum annuum). La síntesis y caracterización de las NPs mencionadas se realizó mediante el método de sol-gel. La aplicación foliar de las NPs a las plantas se hizo semanalmente; el diseño experimental empleado fue completamente al azar con cuatro tratamientos y cinco repeticiones. Los datos obtenidos se procesaron mediante un análisis de varianza y prueba de rango múltiple Tukey (p≤0.05). Los resultados señalan que las plantas expuestas a la aplicación de NPsZnO + Ag al 2.5% en peso, tuvieron significativamente mayor crecimiento y producción de biomasa en comparación con las plantas del tratamiento control, mostrando valores superiores de altura (16.8%), área foliar (30.3%), producción de biomasa total (59.5%), biomasa seca de raíz (112.5%), biomasa seca de tallo (76%) y longitud de raíz (24.4%). También se observó un incremento del índice de clorofila (8%) y número de hojas (32.6%). El efecto promotor de crecimiento de las NPs aplicadas podría atribuirse a la actividad del zinc como precursor de la producción de auxinas que promueven división y elongación celular; así como por su influencia en la reactividad del ácido indolacético, el cual actúa como fitoestimulante hormonal. También puede ser factible que las NPs estudiadas estén involucradas en la biosíntesis de citoquininas y giberelinas; así como en la inducción de mayor actividad de enzimas antioxidantes.

Background: The minor BCR-ABL (e1;a2) transcript oncogene is the most common genetic alteration in adults with acute lymphoblastic leukaemia (ALL). It is associated with a poor prognosis. Aim: To determine the frequency of minor BCR-ABL (e1;a2) transcript oncogene expression in ALL patients in Mexico. Material and methods: A cohort of 411 patients with de novo ALL were tested for the oncogene using reverse transcription polymerase chain reaction (RT-PCR). Results: The oncogene was found in 14% (n = 57) of the study population. Mean age was 29 years, and 53% were male. Median leucocyte count was 53 × 103 μl. Conclusion: Prevalence of BCR-ABL expression by RT-PCR has not previously been reported in Mexico. Our laboratory found a higher prevalence than that reported in Latin-American series, but lower than that reported for the European population.

Molecular markers in leukaemia are essential to diagnose, establish prognosis factors and determine the correct treatment of patients; therefore, it is imperative to include molecular biology studies, so that, combined with cytomorphology and immunophenotyping studies, they constitute the differential diagnosis of these neoplasias. It is extremely important to implement a panel of molecular markers that allows us to detect oncogenes derived from chromosomal translocations, genes derived from epigenetic alterations and drug-resistant genes. A panel of molecular markers that included 11 genes derived from chromosomal translocations BCR-ABL major and minor breakpoints, E2A-PBX1, MLL-AF4, TEL-AML1, PML-RARα, AML1-ETO was standardised; cancer testis antigens (CTA) derived from NY-ESO1 and MAGE-A3 epigenetic alterations and multi-drug-resistant genes ABCB1 and ABCG2. 30 patients diagnosed with leukaemia from Mexico's General Hospital (Hospital General de Mexico) were included. They suffered from acute lymphoblastic leukaemia (ALL) and acute myeloblastic leukaemia (AML); bone marrow mononuclear cells were used, from which RNA was extracted for the synthesis of cDNA and RT-PCR for each of the markers. In acute lymphoblastic leukaemia (ALL), BCR-ABL biomarkers expressed under 30% (3/10), E2A-PBX1 10% (1/10), ABC-B1 80% (8/10), and ABC-G2 60% (6/10). Patients with acute myeloblastic leukaemia (AML) expressed 30% PML-RARα (3/10), 40% ABC-B1 (4/10), and 10% ABC-G2 (1/10). Lastly, in patients with chronic myeloid leukaemia (CML), BCR-ABL was over 100% (10/10), ABC-B1 20% (2/10), and ABC-G2 50% (5/10). The presence of transcripts from chimeric genes minor BCR-ABL and E2A-PBX1 in ALL; PML-RARα in AML; and major BCR-ABL in CML, confirms the importance that the panel of molecular markers has in strengthening the diagnosis and prognosis of these conditions.

Los efectos de la presencia de un corredor en la selva Lacandona, en México, en la riqueza de especies de félidos silvestres Los félidos silvestres se encuentran entre las especies más vulnerables ante la pérdida de hábitat causada por la fragmentación de los ecosistemas. Se analizó el efecto de la presencia de un corredor estructural, definido como una franja de vegetación que conecta dos fragmentos de hábitat, en la riqueza y ocupación de félidos en tres sitios de Marqués de Comillas, en Chiapas: uno comprende dos fragmentos de bosque aislados, otro presenta un corredor estructural y el último se encuentra dentro de la reserva de la biosfera Montes Azules. Se encontraron cuatro especies en el interior de la Reserva, cinco en el corredor estructural y únicamente dos (L. pardalis y H. yagouaroundi) en los fragmentos de bosque aislados. La presencia del corredor no afectó de forma significativa a la ocupación, pero debido a la baja tasa de detección, se necesita seguir investigando para descartar diferencias. Nuestros resultados resaltan la necesidad de manejar la conectividad del hábitat en los bosques remanentes para lograr la conservación de la comunidad de félidos en Marqués de Comillas, en Chiapas, México.

We present 2D projections of 3D simulations of the quiet-sun radio-emission, at different frequencies on the centimeter-submillimeter wavelength range (specifically at 1.4, 3.9, 17, 34, 43, 110, 212 and 250 GHz). We have built a 3D, spherically symmetric, solar model and solved the classical equation of radiative transfer using quiet-sun temperature and electronic density models. We compare our results with Nobeyama Radio Heliograph observations at 17 GHz. The 3.9 and 43 GHz images will be useful to calibrate the observations of the new 5 meter millimeter telescope (RT5) which is going to be installed at “Sierra Negra” Volcano, in the state of Puebla, México, at an altitude of 4,600 m. over the sea level. This project is a collaboration between Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE) and Universidad Nacional Autónoma de México (UNAM).

Presentamos imágenes bidimensionales de simulaciones en 3D de la radioemisión solar en su régimen quieto a diferentes frecuencias, que van desde longitudes de onda centimétricas hasta submilimétricas (1.4, 3.9, 17, 34, 43, 110, 212 y 250 GHz). Construimos un modelo solar esférico 3D y resolvimos la ecuación clásica de transporte radiativo usando temperaturas y densidades electrónicas para el Sol Quieto. Comparamos nuestros resultados con observaciones del Nobeyama Radio Heliograph a 17 GHz. Las imágenes obtenidas a frecuencias de 3.9 GHz y 43 GHz serán de gran ayuda para calibrar las observaciones del nuevo telescopio milimétrico (RT5) que está siendo instalado en el Volcán "Sierra Negra", en el estado de Puebla, México, a una altitud de 4,600 m. Este proyecto es una colaboración entre el Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE) y la Universidad Nacional Autónoma de México (UNAM). doi: https://doi.org/10.22201/igeof.00167169p.2008.47.3.83

Os sistemas agroflorestais podem aliar produção de alimentos com conservação dos recursos naturais, buscando economia de fertilizantes a partir da reciclagem de nutrientes. A produção de fitomassa e o aporte de nutrientes foram quantificados num cultivo em aléias e em área de vegetação nativa de cerrado em Botucatu (SP), com vistas em verificar as influências do sistema agroflorestal nos atributos químicos do solo. A leucena foi plantada em linhas em 1987, com espaçamento de 6 m, após calagem e aplicação de P. As linhas da leguminosa foram podadas anualmente, permitindo o cultivo intercalar de centeio + aveia e milho + feijão, durante a estação seca e chuvosa, respectivamente. A produção anual de fitomassa no sistema agroflorestal foi de 11.036 kg ha-1 de massa seca, com um aporte mineral pelas plantas de (kg ha-1) 149,0 de N, 9,4 de P, 70,0 de K, 75,2 de Ca e 31,1 de Mg. O pH do solo e os teores de Ca e Mg nesse sistema foram superiores aos do cerrado, o que se atribuiu ao efeito do calcário. A adubação verde, principalmente a fitomassa da leucena, colaborou na alteração dos teores de matéria orgânica, N e P no solo sob cultivo em aléias.

La lucilie bouchère du bétail (Cochliomyia hominivorax Coquerel) constitue un fléau important pour l'élevage dans le Nouveau Monde en raison de pertes sévères infligées aux animaux à sang chaud ainsi qu'à l'homme. Pour vérifier la présence de l'insecte à Cuba, une enquête à été réalisée au moyen d'un système de surveillance épizootique avec des carrés géographiques. La lucilie bouchère a été détectée dans 54,8 % des cas de myiases à travers toute l'île, affectant différentes espèces animales, les bovins en premier lieu, suivis des porcins, ovins et autres. Les petites blessures sont apparues comme le premier facteur favorisant le développement de la lucilie. Les raisons de la présence de la lucilie bouchère sans incidence grave sur le cheptel cubain sont discutées.

Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ∼5.0 × 1014 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.

VAMOS1 was a prototype detector built in 2011 at an altitude of 4100 m a.s.l. in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design, construction techniques and data acquisition system of the HAWC observatory. HAWC is an air-shower array currently under construction at the same site of VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water Cherenkov detectors and two different data acquisition systems. It was in operation between October 2011 and May 2012 with an average live time of 30%. Besides the scientific verification purposes, the eight months of data were used to obtain the results presented in this paper: the detector response to the Forbush decrease of March 2012, and the analysis of possible emission, at energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B.

The first limits on the prompt emission from the long gamma-ray burst (GRB) 130427A in the >100 GeV energy band are reported. GRB 130427A was the most powerful burst ever detected with a redshift z ≲ 0.5 and featured the longest lasting emission above 100 MeV. The energy spectrum extends at least up to 95 GeV, clearly in the range observable by the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory, a new extensive air shower detector currently under construction in central Mexico. The burst occurred under unfavorable observation conditions, low in the sky and when HAWC was running 10% of the final detector. Based on the observed light curve at MeV-GeV energies, eight different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC detector, which will be completed soon. The detection rate of the full HAWC detector may be as high as one to two GRBs per year. A detection could provide important information regarding the high energy processes at work and the observation of a possible cut-off beyond the Fermi Large Area Telescope energy range could be the signature of gamma-ray absorption, either in the GRB or along the line of sight due to the extragalactic background light.

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19° North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi-TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from nonluminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross sections below thermal. HAWC should also be sensitive to nonthermal cross sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.

The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic rays at TeV energies. The detector is still under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on 4.9 × 1010 events recorded between 2013 June and 2014 February shows anisotropy at the 10-4 level on angular scales of about 10°. The HAWC cosmic-ray sky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to l = 15 contribute significantly to the excesses.