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

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