Search results for "matter [quantum chromodynamics]"
showing 10 items of 162 documents
Seneca on the Nature of Things: Moral Concerns and Theories of Matter in Natural Questions 6
2017
It is generally recognized that Lucretius' treatment of earthquakes and pestilences (6.535-607; 1090-1286) exerted great influence on Book 6 of Seneca's Natural Questions. But while a large consensus exists that both authors tend to emphasize the moral value of scientific knowledge, further research is needed with respect to Seneca's “technical” re-use of Epicurean physics and meteorology. In the present paper, I shall address this issue in three stages. First, I will analyze the structure and intellectual goals of Seneca's “doxographic” review of seismological theories (6.5-20). Far from being a doxographic account sensu proprio, such a careful review constructs the inspiring image of an i…
Lo verosímil en la ética de Aristóteles: una aporía en el vocabulario filosófico griego
2007
While the mainstream of modern moral philosophy has always assumed that the characteristic situation in moral judgments should be the certitude, Aristotle’s moral philosophy is dominated by the idea of verisimilitude. As a matter of fact, its main concept, namely «virtue», is doubly permeated by this idea, both in its psychological and epistemological sides: we cannot know with certitude (only with verisimilitude) what is entailed by the adscription of a virtue (e.g. generosity), both generally and in a particular case. Nevertheless, verisimilitude is a good enough ground for action.<br><br>Mientras que la corriente principal de la filosofía moral moderna da por supuesto que la …
Implications for dark matter direct detection in the presence of LIGO-motivated primordial black holes
2019
We discuss formation of dark matter (DM) mini-halos around primordial black holes (PBHs) and its implication on DM direct detection experiments, including axion searches. Motivated by LIGO observations, we consider $f_{\textrm{DM}} \simeq 0.01$ as the fraction of DM in PBHs with masses $10 M_{\odot} - 70 M_{\odot}$. In this case, we expect the presence of dressed PBHs after Milky Way halo formation with mini-halo masses peaked around $M_{\textrm{halo}} \sim (50-55) M_{\textrm{PBH}}$. We analyze the effect of tidal forces acting on dressed PBHs within the Milky Way galaxy. In the solar neighborhood, the mini-halos are resistant against tidal disruption from the mean-field potential of the ga…
Brane-world and loop cosmology from a gravity–matter coupling perspective
2015
We show that the effective brane-world and the loop quantum cosmology background expansion histories can be reproduced from a modified gravity perspective in terms of an $f(R)$ gravity action plus a $g(R)$ term non-minimally coupled with the matter Lagrangian. The reconstruction algorithm that we provide depends on a free function of the matter density that must be specified in each case and allows to obtain analytical solutions always. In the simplest cases, the function $f(R)$ is quadratic in the Ricci scalar, $R$, whereas $g(R)$ is linear. Our approach is compared with recent results in the literature. We show that working in the Palatini formalism there is no need to impose any constrai…
El dilema de la lechuza ¿Qué relación debe tener la filosofía con su historia?
2020
Resumen La historia parece tener una importancia especial en el campo de la filosofía, en pocas disciplinas encontramos tantas referencias a los autores y problemas del pasado. Sin embargo, esto puede ser una simple cuestión de hecho: hasta ahora hemos creído que enseñar la historia de la filosofía era formativo para los futuros filósofos, pero tal creencia puede cambiar. También podría ser una cuestión de puro interés profesional: algunos estudiamos la historia de la disciplina, y tratamos de justificar esa dedicación alegando que ésta puede ser útil, en cierta medida, para los pensadores contemporáneos. En este artículo, sin embargo, abogaré por una comprensión de nuestra historia como al…
Ultra-fast-prototyping of PMMA structures for micro-engineering applications: Choosing the right material
2017
Machining of poly(methyl methacrylate) (PMMA) by laser has been extensively studied in engineering research for several applications including microfluidic manufacturing and rapid prototyping. However, very few investigations have taken into consideration the wide range of physico-chemical characteristics of commercially available PMMA that can often affect the quality of the laser-machined structures. These characteristics are often ignored, with many manufacturing publications focusing on a single source of PMMA. To understand the different bonding strengths and laser-cut qualities in the context of our ultra-fast prototyping technique, four types of PMMA have been examined. Molecular wei…
Light Dark Matter Search with Ionization Signals in XENON1T
2019
We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keVee, we observe <1 event/(tonne day keVee), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses mχ within 3–6 GeV/c2, DM-electron scattering for mχ>30 MeV/c2, a…
Conceptual design of the International Axion Observatory (IAXO)
2014
The International Axion Observatory (IAXO) will be a forth generation axion helioscope. As its primary physics goal, IAXO will look for axions or axion-like particles (ALPs) originating in the Sun via the Primakoff conversion of the solar plasma photons. In terms of signal-to-noise ratio, IAXO will be about 4-5 orders of magnitude more sensitive than CAST, currently the most powerful axion helioscope, reaching sensitivity to axion-photon couplings down to a few $\times 10^{-12}$ GeV$^{-1}$ and thus probing a large fraction of the currently unexplored axion and ALP parameter space. IAXO will also be sensitive to solar axions produced by mechanisms mediated by the axion-electron coupling $g_{…
Selective Brain Network and Cellular Responses Upon Dimethyl Fumarate Immunomodulation in Multiple Sclerosis
2019
Background: Efficient personalized therapy paradigms are needed to modify the disease course and halt gray (GM) and white matter (WM) damage in patients with multiple sclerosis (MS). Presently, promising disease-modifying drugs show impressive efficiency, however, tailored markers of therapy responses are required. Here, we aimed to detect in a real-world setting patients with a more favorable brain network response and immune cell dynamics upon dimethyl fumarate (DMF) treatment. Methods: In a cohort of 78 MS patients we identified two thoroughly matched groups, based on age, disease duration, disability status and lesion volume, receiving DMF (n = 42) and NAT (n = 36) and followed them ove…
Apoe genotypes and brain imaging classes in normal cognition, mild cognitive impairment, and alzheimer’s disease: A longitudinal study
2020
Objective: To evaluate in 419 stroke-free cognitively normal subjects (CN) aged 45-82 years covering during a long prospective study (11.54 ± 1.47 years) the preclinical to dementia spectrum: 1) the distribution of small vessel disease (V) and brain atrophy (A) aggregated as following: V−/A−, V−/A+, V+/A−, V+/A+; 2) the relationship of these imaging classes with individual apolipoprotein E (APOE) genotypes; 3) the risk of progression to Alzheimer Disease (AD) of the individual APOE genotypes. Methods: Participants underwent one baseline (t0), and 4 clinical and neuropsychological assessments (t1,t2,t3, and t4). Brain MRI was performed in all subjects at t0, t2, t3 and t4.. White matter hyp…