2,851 research outputs found
X-Ray Fluorescence Analysis of Fine Atmospheric Aerosols from a Site in Mexico City
A study was performed in the Winter of the year 2015 in a Southwestern site in the MAMC (Ciudad Universitaria), collecting PM2.5 samples with a Mini Vol. As a part of wider study focused to fully characterize aerosols at this site, an X-ray Fluorescence (XRF) spectrometer (based on an Rh X-ray tube) built to analyze environmental samples, was used to characterize the sample set. A total of 16 elements (Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb) were detected in most samples and mean concentrations were calculated. Cluster analysis was also applied to the elemental concentrations to find possible correlations among the elements
The shifting classroom: impact of heightened seasonal heat in education through sentiment and topic modeling
This research applies text mining techniques to examine sentiments and themes among Filipino students adjusting to full in-person classes after pandemic-driven flexible learning, focusing on their experiences during April to June 2023âa period usually marked by vacations due to intense heat. By applying the natural language toolkit (NLTK) for sentiment analysis and Scikit-learn for topic modeling, the study gathered data from Filipino students on their in-person class experiences during this unique calendar shift. Post data cleaning, NLTK was used for sentiment analysis and latent Dirichlet allocation for topic modeling. The findings indicate that the high temperatures adversely affected students, as evidenced by frequent references to terms such as âroom,â âfocus,â and âhard.â The study identified a mix of positive and negative sentiments and highlighted key issues like academic challenges and the learning environmentâs impact. This study also offered insights into studentsâ coping strategies during extreme heat. These results stressed the importance of considering environmental factors in educational planning and provide actionable insights for institutions to enhance the in-person learning experience, particularly in challenging weather conditions. Moreover, this study demonstrates the effectiveness of sentiment analysis and topic modeling in understanding and unraveling student experiences in specific contexts
Improvements to the X-ray Spectrometer at the Aerosol Laboratory, Instituto de FĂsica, UNAM
Due to the demands of better (accurate and precise) analytical results using X-ray Fluorescence (XRF) at the Aerosol Laboratory, Instituto de FĂsica, UNAM, it was necessary to carry out improvements in instrumentation and analytical procedures in the x-ray spectrometer located in this facility. A new turbomolecular vacuum system was installed, which allows reaching the working pressure in a shorter time. Characteristic x-rays are registered with a Silicon Drift Detector, or SDD, (8 mm thick Be window, 140 eV at 5.9 keV resolution), working directly in a high-vacuum, permitting the detection of x-rays with energies as low as 1 keV (Na Ka) and higher counting rates than in the past. Due to the interference produced by the Rh L x-rays emitted by the tube normally used for atmospheric and food analysis with Cl K x-rays, another tube with a W anode was mounted in the spectrometer to avoid this interference, with the possibility to select operation with any of these tubes. Examples of applications in atmospheric aerosols and other samples are presented, to demonstrate the enhanced function of the spectrometer. Other future modifications are also explained
Insm1 controls development of pituitary endocrine cells and requires a SNAG domain for function and for recruitment of histone-modifying factors
The Insm1 gene encodes a zinc finger factor expressed in many endocrine organs. We show here that Insm1 is required for differentiation of all endocrine cells in the pituitary. Thus, in Insm1 mutant mice, hormones characteristic of the different pituitary cell types (thyroid-stimulating hormone, follicle-stimulating hormone, melanocyte-stimulating hormone, adrenocorticotrope hormone, growth hormone and prolactin) are absent or produced at markedly reduced levels. This differentiation deficit is accompanied by upregulated expression of components of the Notch signaling pathway, and by prolonged expression of progenitor markers, such as Sox2. Furthermore, skeletal muscle-specific genes are ectopically expressed in endocrine cells, indicating that Insm1 participates in the repression of an inappropriate gene expression program. Because Insm1 is also essential for differentiation of endocrine cells in the pancreas, intestine and adrenal gland, it is emerging as a transcription factor that acts in a pan-endocrine manner. The Insm1 factor contains a SNAG domain at its N-terminus, and we show here that the SNAG domain recruits histone-modifying factors (Kdm1a, Hdac1/2 and Rcor1-3) and other proteins implicated in transcriptional regulation (Hmg20a/b and Gse1). Deletion of sequences encoding the SNAG domain in mice disrupted differentiation of pituitary endocrine cells, and resulted in an upregulated expression of components of the Notch signaling pathway and ectopic expression of skeletal muscle-specific genes. Our work demonstrates that Insm1 acts in the epigenetic and transcriptional network that controls differentiation of endocrine cells in the anterior pituitary gland, and that it requires the SNAG domain to exert this function in vivo
How Trade Liberalization and Labor Development Could Coincide in the Philippines
As the world adapts to the rapid pace of globalization in the 21st century, countries ease trade restrictions by gradually removing tariffs and non-tariff barriers to incentivize the free flow of goods across nations. This prevalence of trade liberalization policies propelled policymakers and economists to investigate the relationship between trade reforms and economic outcomes including wage inequality around the world. They found that trade liberalization, on average, has had a positive impact on economic growth, but prior studies that examine the effects of trade liberalization on wage inequality in developing countries have found mixed results. Recently, Murakami (2021) examined the impact of trade liberalization on wage inequality in Chile through the reduction in effective tariffs brought about by the regional trade agreements of the country. Following his empirical strategy, we examine the impact of trade liberalization on wage inequality in the Philippines. In this policy brief, we provide insights on our findings and policy recommendations that the Philippines can undertak
Work and heat fluctuations in two-state systems: a trajectory thermodynamics formalism
Two-state models provide phenomenological descriptions of many different
systems, ranging from physics to chemistry and biology. We investigate work
fluctuations in an ensemble of two-state systems driven out of equilibrium
under the action of an external perturbation. We calculate the probability
density P(W) that a work equal to W is exerted upon the system along a given
non-equilibrium trajectory and introduce a trajectory thermodynamics formalism
to quantify work fluctuations in the large-size limit. We then define a
trajectory entropy S(W) that counts the number of non-equilibrium trajectories
P(W)=exp(S(W)/kT) with work equal to W. A trajectory free-energy F(W) can also
be defined, which has a minimum at a value of the work that has to be
efficiently sampled to quantitatively test the Jarzynski equality. Within this
formalism a Lagrange multiplier is also introduced, the inverse of which plays
the role of a trajectory temperature. Our solution for P(W) exactly satisfies
the fluctuation theorem by Crooks and allows us to investigate
heat-fluctuations for a protocol that is invariant under time reversal. The
heat distribution is then characterized by a Gaussian component (describing
small and frequent heat exchange events) and exponential tails (describing the
statistics of large deviations and rare events). For the latter, the width of
the exponential tails is related to the aforementioned trajectory temperature.
Finite-size effects to the large-N theory and the recovery of work
distributions for finite N are also discussed. Finally, we pay particular
attention to the case of magnetic nanoparticle systems under the action of a
magnetic field H where work and heat fluctuations are predicted to be
observable in ramping experiments in micro-SQUIDs.Comment: 28 pages, 14 figures (Latex
The drivers of change for the contribution of small farms to regional food security in Europe
The capacity of the food system to respond to the economic, demographic and environmental challenges ahead has become a topic of increasing interest, with particular attention to the roles and responsibilities of the different actors to ensure more sustainable food systems that can guarantee food and nutrition security for all. In this paper we approach the need to better understand the factors that can condition the potential contribution of small farms to regional food and nutrition security in Europe, acknowledging the role that small farms play in Europe at present. The analysis is based on a survey to 94 experts from 17 regions (NUTS3 level) in 11 different European countries, which identified the drivers of change according to the regional experts. These drivers were then categorized and their relative relevance assessed. The results indicate that some relevant drivers in the European context are linked to the capacity to adopt technologies and practices allowing adaptation to climate change, and the capacity to connect to food markets, with emphasis in the need for cooperation and collective action. The weight of other more European-specific drivers such as âconsumer values and habitsâ reveal that the future role of small farms will be very dependent on a societal change, with equity becoming a relevant component of consumersâ choice
Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC
We present results from daily monitoring of gamma rays in the energy range
to TeV with the first 17 months of data from the High
Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2
steradians and duty cycle of % are unique features compared to other TeV
observatories that allow us to observe every source that transits over HAWC for
up to hours each sidereal day. This regular sampling yields
unprecedented light curves from unbiased measurements that are independent of
seasons or weather conditions. For the Crab Nebula as a reference source we
find no variability in the TeV band. Our main focus is the study of the TeV
blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a
power law index and
an exponential cut-off
TeV. For Mrk 501, we find an index and exponential cut-off TeV. The light curves for both sources show clear
variability and a Bayesian analysis is applied to identify changes between flux
states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab
Nebula flux by a factor of approximately five. For Mrk 501, several transits
show fluxes in excess of three times the Crab Nebula flux. In a comparison to
lower energy gamma-ray and X-ray monitoring data with comparable sampling we
cannot identify clear counterparts for the most significant flaring features
observed by HAWC.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical
Journa
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