2,625 research outputs found
The growth and erosion of cinder cones in Guatemala and El Salvador: Models and statistics
Morphologic data for 147 cinder cones in southern Guatemala andwestern El Salvador are comparedwith data from
the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato
volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of
110+/-50 m, an average basal diameter of 660+/-230 m and an average top diameter of 180+/-150 m. The
generalmorphology of these cones can be described by their average cone angle of slope (24+/-7), average heightto-
radius ratio (0.33+/-0.09) and their flatness (0.24+/-0.18). Although the mean values for the Guatemalan
cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field,
California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of
morphologies encompasses almost all of those observed worldwide for cinder cones.
Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El
Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka.
Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of
those studied) is there clear evidence of degradation with age.
Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies
observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of
eruption
The growth and erosion of cinder cones in Guatemala and El Salvador: Models and statistics
Morphologic data for 147 cinder cones in southern Guatemala andwestern El Salvador are comparedwith data from
the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato
volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of
110+/-50 m, an average basal diameter of 660+/-230 m and an average top diameter of 180+/-150 m. The
generalmorphology of these cones can be described by their average cone angle of slope (24+/-7), average heightto-
radius ratio (0.33+/-0.09) and their flatness (0.24+/-0.18). Although the mean values for the Guatemalan
cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field,
California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of
morphologies encompasses almost all of those observed worldwide for cinder cones.
Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El
Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka.
Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of
those studied) is there clear evidence of degradation with age.
Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies
observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of
eruption
The Magnetic Distortion Calibration System of the LHCb RICH1 Detector
The LHCb RICH1 detector uses hybrid photon detectors (HPDs) as its optical
sensors. A calibration system has been constructed to provide corrections for
distortions that are primarily due to external magnetic fields. We describe
here the system design, construction, operation and performance.Comment: 9 pages, 14 figure
“Thyroid nodular disease and PTEN mutation in a multicentre series of children with PTEN hamartoma tumor syndrome (PHTS)”
The CubeSat Mission FUTURE: A Preliminary Analysis to Validate the On-Board Autonomous Orbit Determination
Theory of mechanical unfolding of homopolymer globule: all-or-none transition in force-clamp mode vs phase coexistence in position-clamp mode
Equilibrium mechanical unfolding of a globule formed by long flexible
homopolymer chain collapsed in a poor solvent and subjected to an extensional
force f (force-clamp mode) or extensional deformation D (position-clamp mode)
is studied theoretically. Our analysis, like all previous analysis of this
problem, shows that the globule behaves essentially differently in two modes of
extension. In the force-clamp mode, mechanical unfolding of the globule with
increasing applied force occurs without intramolecular microphase segregation,
and at certain threshold value of the pulling force the globule unfolds as a
whole ("all-or-none" transition). The value of the threshold force and the
corresponding jump in the distance between the chain ends increase with a
deterioration of the solvent quality and/or with an increase in the degree of
polymerization. In the position-clamp mode, the globule unfolding occurs via
intramolecular microphase coexistence of globular and extended microphases
followed by an abrupt unraveling transition. Reaction force in the microphase
segregation regime demonstrates an "anomalous" decrease with increasing
extension. Comparison of deformation curves in force and position-clamp modes
demonstrates that at weak and strong extensions the curves for two modes
coincide, differences are observed in the intermediate extension range. Another
unfolding scenario is typical for short globules: in both modes of extension
they unfold continuously, without jumps or intramolecular microphase
coexistence, by passing a sequence of uniformly elongated configurations.Comment: 19 pages, 13 figures, 1 tabl
Sabotage in Contests: A Survey
A contest is a situation in which individuals expend irretrievable resources to win valuable prize(s). ‘Sabotage’ is a deliberate and costly act of damaging a rival’s' likelihood of winning the contest. Sabotage can be observed in, e.g., sports, war, promotion tournaments, political or marketing campaigns. In this article, we provide a model and various perspectives on such sabotage activities and review the economics literature analyzing the act of sabotage in contests. We discuss the theories and evidence highlighting the means of sabotage, why sabotage occurs, and the effects of sabotage on individual players and on overall welfare, along with possible mechanisms to reduce sabotage. We note that most sabotage activities are aimed at the ablest player, the possibility of sabotage reduces productive effort exerted by the players, and sabotage may lessen the effectiveness of public policies, such as affirmative action, or information revelation in contests. We discuss various policies that a designer may employ to counteract sabotage activities. We conclude by pointing out some areas of future research
Impact of social determinants on antiretroviral therapy access and outcomes entering the era of universal treatment for people living with HIV in Italy
Background: Social determinants are known to be a driving force of health inequalities, even in high income countries. Aim of our study was to determine if these factors can limit antiretroviral therapy (ART) access, outcome and retention in care of people living with HIV (PLHIV) in Italy. Methods: All ART naïve HIV+ patients (pts) of Italian nationality enrolled in the ICONA Cohort from 2002 to 2016 were included. The association of socio-demographic characteristics (age, sex, risk factor for HIV infection, educational level, occupational status and residency area) with time to: ART initiation (from the first positive anti-HIV test), ART regimen discontinuation, and first HIV-RNA < 50 cp/mL, were evaluated by Cox regression analysis, Kaplan Meier method and log-rank test. Results: A total of 8023 HIV+ pts (82% males, median age at first pos anti-HIV test 36 years, IQR: 29-44) were included: 6214 (77.5%) started ART during the study period. Women, people who inject drugs (PWID) and residents in Southern Italy presented the lowest levels of education and the highest rate of unemployment compared to other groups. Females, pts aged > 50 yrs., unemployed vs employed, and people with lower educational levels presented the lowest CD4 count at ART initiation compared to other groups. The overall median time to ART initiation was 0.6 years (yrs) (IQR 0.1-3.7), with a significant decrease over time [2002-2006 = 3.3 yrs. (0.2-9.4); 2007-2011 = 1.0 yrs. (0.1-3.9); 2012-2016 = 0.2 yrs. (0.1-2.1), p < 0.001]. By multivariate analysis, females (p < 0.01) and PWID (p < 0.001), presented a longer time to ART initiation, while older people (p < 0.001), people with higher educational levels (p < 0.001), unemployed (p = 0.02) and students (p < 0.001) were more likely to initiate ART. Moreover, PWID, unemployed vs stable employed, and pts. with lower educational levels showed a lower 1-year probability of achieving HIV-RNA suppression, while females, older patients, men who have sex with men (MSM), unemployed had higher 1-year risk of first-line ART discontinuation. Conclusions: Despite median time to ART start decreased from 2002 to 2016, socio-demographic factors still contribute to disparities in ART initiation, outcome and durability
Precision luminosity measurements at LHCb
Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy √s. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for √s = 2.76, 7 and 8 TeV (proton-proton collisions) and for √sNN = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at √s = 8 TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determines the luminosity with a precision of 1.16%. This represents the most precise luminosity measurement achieved so far at a bunched-beam hadron collider
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