158 research outputs found
The scattering of SH waves by a finite crack with a superposition based diffraction technique
The problem of diffraction of cylindrical and plane SH waves by a finite crack is revisited -- We construct an approximate solution by the addition of independent diffracted terms -- We start with the derivation of the fundamental case of a semi-infinite crack obtained as a degenerate case of generalized wedge -- This building block is then used to compute the diffraction of the main incident waves -- The interaction between the opposite edges of the crack is then considered one term at a time until a desired tolerance is reached -- We propose a recipe to determine the number of required interactions as a function of frequency -- The solution derived with the superposition technique can be applied at low and high frequencie
Waveforms of molecular oscillations reveal circadian timekeeping mechanisms
Circadian clocks play a pivotal role in orchestrating numerous physiological
and developmental events. Waveform shapes of the oscillations of protein
abundances can be informative about the underlying biochemical processes of
circadian clocks. We derive a mathematical framework where waveforms do reveal
hidden biochemical mechanisms of circadian timekeeping. We find that the cost
of synthesizing proteins with particular waveforms can be substantially reduced
by rhythmic protein half-lives over time, as supported by previous plant and
mammalian data, as well as our own seedling experiment. We also find that
previously-enigmatic, cyclic expression of positive arm components within the
mammalian and insect clocks allows both a broad range of peak time differences
between protein waveforms and the symmetries of the waveforms about the peak
times. Such various peak-time differences may facilitate tissue-specific or
developmental stage-specific multicellular processes. Our waveform-guided
approach can be extended to various biological oscillators, including
cell-cycle and synthetic genetic oscillators.Comment: Supplementary material is available at the journal websit
Data sources for drug utilization research in Latin American countries—A cross-national study: DASDUR-LATAM study
Purpose: Drug utilization research (DUR) contributes to inform policymaking and to strengthen health systems. The availability of data sources is the first step for conducting DUR. However, documents that systematize these data sources in Latin American (LatAm) countries are not known. We compiled the potential data sources for DUR in the LatAm region. Methods: A network of DUR experts from nine LatAm countries was assembled and experts conducted: (i) a website search of the government, academic, and private health institutions; (ii) screening of eligible data sources, and (iii) liaising with national experts in pharmacoepidemiology (via an online survey). The data sources were characterized by accessibility, geographic granularity, setting, sector of the data, sources and type of the data. Descriptive analyses were performed. Results: We identified 125 data sources for DUR in nine LatAm countries. Thirty-eight (30%) of them were publicly and conveniently available; 89 (71%) were accessible with limitations, and 18 (14%) were not accessible or lacked clear rules for data access. From the 125 data sources, 76 (61%) were from the public sector only; 46 (37%) were from pharmacy records; 43 (34%) came from ambulatory settings and; 85 (68%) gave access to individual patient-level data. Conclusions: Although multiple sources for DUR are available in LatAm countries, the accessibility is a major challenge. The procedures for accessing DUR data should be transparent, feasible, affordable, and protocol-driven. This inventory could permit a comparison of drug utilization between countries identifying potential medication-related problems that need further exploration.Fil: Lopes, Luciane C.. University Of Sorocaba; BrasilFil: Salas, Daiana Maribel. University of Pennsylvania; Estados UnidosFil: Osorio de Castro, Claudia Garcia Serpa. Fundación Oswaldo Cruz; BrasilFil: Freitas Leal, Lisiane. McGill University; CanadáFil: Doubova, Svetlana V.. Mexican Institute of Social Security; MéxicoFil: Cañás, Martín. Universidad Nacional Arturo Jauretche; Argentina. Federación Médica de la Provincia de Buenos Aires; ArgentinaFil: Dreser, Anahi. Instituto Nacional de Salud Pública; MéxicoFil: Acosta, Angela. Universidad ICESI; ColombiaFil: Oliveira Baldoni, Andre. Federal University of São João Del-Rei; BrasilFil: de Cássia Bergamaschi, Cristiane. University of Sorocaba; BrasilFil: Marques Mota, Daniel. Brazilian Health Regulatory Agency; BrasilFil: Gómez Galicia, Diana L.. Universidad Autónoma del Estado de Morelos; MéxicoFil: Sepúlveda Viveros, Dino. Universidad de Chile; ChileFil: Narvaez Delgado, Edgard. No especifíca;Fil: da Costa Lima, Elisangela. Universidade Federal do Rio de Janeiro; BrasilFil: Chandia, Felipe Vera. Pontificia Universidad Católica de Chile; ChileFil: Ferre, Felipe. Universidade Federal de Minas Gerais; BrasilFil: Marin, Gustavo Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Olmos, Ismael. State Health Services Administration; UruguayFil: Zimmermann, Ivan R.. Universidade do Brasília; BrasilFil: Fulone, Izabela. University of Sorocaba; BrasilFil: Roldán Saelzer, Juan. Instituto de Salud Pública; ChileFil: Sánchez Salgado, Juan Carlos. No especifíca;Fil: Castro Pastrana, Lucila I.. Universidad de Las Américas de Puebla; MéxicoFil: de Souza, Luiz Jupiter Carneiro. Fundación Oswaldo Cruz; BrasilFil: Machado Beltrán, Manuel. Universidad Nacional de Colombia; ColombiaFil: Tolentino Silva, Marcus. University of Sorocaba; BrasilFil: Mena, María Belén. Universidad Central del Ecuador; EcuadorFil: de França Fonteles, Marta Maria. Universidade Federal do Ceara; BrasilFil: Urtasun, Martín Alejandro. Universidad Nacional Arturo Jauretche; Argentina. Federación Médica de la Provincia de Buenos Aires; Argentin
Inflammation, genetic background and longevity
Ageing is an inexorable intrinsic process
that affects all cells, tissues, organs and individuals.
Due to a diminished homeostasis and increased
organism frailty, ageing causes a reduction of the
response to environmental stimuli and, in general, is
associated to an increased predisposition to illness and
death. Actually, it is characterized by a state of reduced
ability to maintain health and general homeodynamics
of the organism.Alarge part of the ageing phenotype is
explained by an imbalance between inflammatory and
anti-inflammatory networks, which results in the low
grade chronic pro-inflammatory status of ageing,
‘‘inflamm-ageing’’. It is strictly linked to immunosenescence,
and on the whole they are the major
contributory factors to the increased frequency of
morbidity and mortality among elderly. Inflammageing
is compatible with longevity; even if centenarians
have an increased level of inflammatory mediators
in comparison to old subjects and they are very frail,
they also have high level of anti-inflammatory cytokines
together with protective genotypes. Actually,
data on case control studies performed in Italian
centenarians suggest that a pro-inflammatory genotype
is unfavourable to reach extreme longevity in good
health and likely favours the onset of age-related
diseases such as cardiovascular diseases and Alzheimer’s
disease, the leading causes of mortality and
disability in the elderly. However, many associations
between gene variants and longevity have been found
only in Italian population. This should not be unexpected,
since ageing and longevity are complex traits
resulting not only and not exclusively from genetics,
but rather from the interactions between genetics,
environment and chance
Endocannabinoid Regulation of Acute and Protracted Nicotine Withdrawal: Effect of FAAH Inhibition
Evidence shows that the endocannabinoid system modulates the addictive properties of nicotine. In the present study, we hypothesized that spontaneous withdrawal resulting from removal of chronically implanted transdermal nicotine patches is regulated by the endocannabinoid system. A 7-day nicotine dependence procedure (5.2 mg/rat/day) elicited occurrence of reliable nicotine abstinence symptoms in Wistar rats. Somatic and affective withdrawal signs were observed at 16 and 34 hours following removal of nicotine patches, respectively. Further behavioral manifestations including decrease in locomotor activity and increased weight gain also occurred during withdrawal. Expression of spontaneous nicotine withdrawal was accompanied by fluctuation in levels of the endocannabinoid anandamide (AEA) in several brain structures including the amygdala, the hippocampus, the hypothalamus and the prefrontal cortex. Conversely, levels of 2-arachidonoyl-sn-glycerol were not significantly altered. Pharmacological inhibition of fatty acid amide hydrolase (FAAH), the enzyme responsible for the intracellular degradation of AEA, by URB597 (0.1 and 0.3 mg/kg, i.p.), reduced withdrawal-induced anxiety as assessed by the elevated plus maze test and the shock-probe defensive burying paradigm, but did not prevent the occurrence of somatic signs. Together, the results indicate that pharmacological strategies aimed at enhancing endocannabinoid signaling may offer therapeutic advantages to treat the negative affective state produced by nicotine withdrawal, which is critical for the maintenance of tobacco use
Is (poly-) substance use associated with impaired inhibitory control? A mega-analysis controlling for confounders.
Many studies have reported that heavy substance use is associated with impaired response inhibition. Studies typically focused on associations with a single substance, while polysubstance use is common. Further, most studies compared heavy users with light/non-users, though substance use occurs along a continuum. The current mega-analysis accounted for these issues by aggregating individual data from 43 studies (3610 adult participants) that used the Go/No-Go (GNG) or Stop-signal task (SST) to assess inhibition among mostly "recreational" substance users (i.e., the rate of substance use disorders was low). Main and interaction effects of substance use, demographics, and task-characteristics were entered in a linear mixed model. Contrary to many studies and reviews in the field, we found that only lifetime cannabis use was associated with impaired response inhibition in the SST. An interaction effect was also observed: the relationship between tobacco use and response inhibition (in the SST) differed between cannabis users and non-users, with a negative association between tobacco use and inhibition in the cannabis non-users. In addition, participants' age, education level, and some task characteristics influenced inhibition outcomes. Overall, we found limited support for impaired inhibition among substance users when controlling for demographics and task-characteristics
- …