Macroscopic effects in attosecond pulse generation

We examine how the generation and propagation of high-order harmonics in a partly ionized gas medium affect their strength and synchronization. The temporal properties of the resulting attosecond pulses generated in long gas targets can be significantly influenced by macroscopic effects, in particular by the intensity in the medium and the degree of ionization. Under some conditions, the use of gas targets longer than the absorption length can lead to the generation of self-compressed attosecond pulses. We show this effect experimentally, using long argon-filled gas cells as generating medium.Comment: 5 pages 4 figure

Protective effects of the thioredoxin and glutaredoxin systems in dopamine-induced cell death

Although the etiology of sporadic Parkinson disease (PD) is unknown, it is well established that oxidative stress plays an important role in the pathogenic mechanism. The thioredoxin (Trx) and glutaredoxin (Grx) systems are two central systems upholding the sulfhydryl homeostasis by reducing disulfides and mixed disulfides within the cell and thereby protecting against oxidative stress. By examining the expression of redox proteins in human postmortem PD brains, we found the levels of Trx1 and thioredoxin reductase 1 (TrxR1) to be significantly decreased. The human neuroblastoma cell line SH-SY5Y and the nematode Caenorhabditis elegans were used as model systems to explore the potential protective effects of the redox proteins against 6-hydroxydopamine (6-OHDA)-induced cytotoxicity. 6-OHDA is highly prone to oxidation, resulting in the formation of the quinone of 6-OHDA, a highly reactive species and powerful neurotoxin. Treatment of human cells with 6-OHDA resulted in an increased expression of Trx1, TrxR1, Grx1, and Grx2, and small interfering RNA for these genes significantly increased the cytotoxic effects exerted by the 6-OHDA neurotoxin. Evaluation of the dopaminergic neurons in C. elegans revealed that nematodes lacking trxr-1 were significantly more sensitive to 6-OHDA, with significantly increased neuronal degradation. Importantly, both the Trx and the Grx systems were also found to directly mediate reduction of the 6-OHDA-quinone in vitro and thus render its cytotoxic effects. In conclusion, our results suggest that the two redox systems are important for neuronal survival in dopamine-induced cell death. © 2014 Elsevier Inc.A.P.F. was supported by Stiftelsen Lars Hiertas Minne and Karolinska Institutet research grants. Research in the Swoboda laboratory was supported by the Swedish Research Council (VR) and the NordForsk Nordic network for C. elegans research. A.M.-V. was supported by the Instituto de Salud Carlos III (Projects PI050065 and PI080557, cofinanced by the Fondo Social Europeo, FEDER) and Junta de Andalucía (Projects P07-CVI-02697 and P08-CVI-03629), Spain. Some C. elegans strains were provided by the CGC, which is funded by the NIH Office of Research Infrastructure Programs (P40 OD010440).Peer Reviewe

Componentes de la tasa de crecimiento poblacional en el negrón especulado de Saskatchewan, Canadá

Breeding range and abundance of White–winged Scoters (Melanitta fusca deglandi) have declined in northwestern North America. Hypotheses proposed to account for this trend are that survival and/or recruitment of females had declined. Thus, we used a reverse–time capture–recapture approach to directly estimate survival, seniority and capture probabilities for females of breeding age at Redberry Lake, Saskatchewan, Canada for 1975–1980 and 2000–2003. We also estimated population size of breeding females for 1975–1985 and 2000–2003 using capture–recapture data. Initially, this local population was in serious decline [95% CL ( ) = 0.89 ± 0.09], but has since stabilized and may be slowly increasing [95% CL ( ) = 1.07 ± 0.11]. This reversal in trajectory apparently resulted from increased recruitment rather than increased apparent survival. Importantly, recent recruitment of adult females appeared to be driven solely by immigration of adult females with no detectable in situ recruitment, suggesting a hypothesis that the local population is being rescued by females produced elsewhere.El rango reproductivo y la abundancia del negrón especulado (Melanitta fusca deglandi) han disminuido en la zona noroeste de América del Norte. La hipótesis propuesta para explicar esta tendencia es que se ha producido una disminución en la supervivencia y/o el reclutamiento de hembras. Por consiguiente, utilizamos un enfoque de captura–recaptura con el tiempo invertido para estimar directamente la supervivencia, la jerarquía y las probabilidades de captura de las hembras en edad reproductora del lago Redberry, Saskatchewan, Canadá, durante los periodos 1975–1980 y 2000– 2003. También estimamos el tamaño poblacional de las hembras reproductoras durante los periodos 1975–1985 y 2000–2003, mediante el empleo de datos de captura–recaptura. En un principio, esta población local experimentó una importante disminución [95% CL ( ) = 0,89 ± 0,09], pero posteriormente se estabilizó, y es posible que poco a poco vaya aumentando [95% CL ( ) = 1,07 ± 0,11]. Por lo visto, la inversión de esta trayectoria se produjo como consecuencia de un mayor reclutamiento, en lugar de una mayor supervivencia aparente. Es importante destacar que el reclutamiento reciente de hembras adultas parece haber obedecido exclusivamente a la migración de hembras adultas sin un reclutamiento detectable in situ, lo que sugiere la hipótesis de que la población local está siendo rescatada por hembras procedentes de otros lugares

Ventricular longitudinal function is associated with microvascular obstruction and intramyocardial haemorrhage.

Microvascular obstruction (MVO) and intramyocardial haemorrhage (IMH) are associated with adverse prognosis, independently of infarct size after reperfused ST-elevation myocardial infarction (STEMI). Mitral annular plane systolic excursion (MAPSE) is a well-established parameter of longitudinal function on echocardiography.We aimed to investigate how acute MAPSE, assessed by a four-chamber cine-cardiovascular MR (CMR), is associated with MVO, IMH and convalescent left ventricular (LV) remodelling.54 consecutive patients underwent CMR at 3T (Intera CV, Philips Healthcare, Best, The Netherlands) within 3 days of reperfused STEMI. Cine, T2-weighted, T2* and late gadolinium enhancement (LGE) imaging were performed. Infarct and MVO extent were measured from LGE images. The presence of IMH was investigated by combined analysis of T2w and T2* images. Averaged-MAPSE (medial-MAPSE+lateral-MAPSE/2) was calculated from 4-chamber cine imaging.44 patients completed the baseline scan and 38 patients completed 3-month scans. 26 (59%) patients had MVO and 25 (57%) patients had IMH. Presence of MVO and IMH were associated with lower averaged-MAPSE (11.7±0.4 mm vs 9.3±0.3 mm; p<0.001 and 11.8±0.4 mm vs 9.2±0.3 mm; p<0.001, respectively). IMH (β=-0.655, p<0.001) and MVO (β=-0.567, p<0.001) demonstrated a stronger correlation to MAPSE than other demographic and infarct characteristics. MAPSE ≤10.6 mm demonstrated 89% sensitivity and 72% specificity for the detection of MVO and 92% sensitivity and 74% specificity for IMH. LV remodelling in convalescence was not associated with MAPSE (AUC 0.62, 95% CI 0.44 to 0.77, p=0.22).Postreperfused STEMI, LV longitudinal function assessed by MAPSE can independently predict the presence of MVO and IMH

Arabidopsis RecQl4A suppresses homologous recombination and modulates DNA damage responses

The DNA damage response and DNA recombination are two interrelated mechanisms involved in maintaining the integrity of the genome, but in plants they are poorly understood. RecQ is a family of genes with conserved roles in the regulation of DNA recombination in eukaryotes; there are seven members in Arabidopsis. Here we report on the functional analysis of the Arabidopsis RecQl4A gene. Ectopic expression of Arabidopsis RecQl4A in yeast RecQ-deficient cells suppressed their hypersensitivity to the DNA-damaging drug methyl methanesulfonate (MMS) and enhanced their rate of homologous recombination (HR). Analysis of three recQl4A mutant alleles revealed no obvious developmental defects or telomere deregulation in plants grown under standard growth conditions. Compared with wild-type Arabidopsis, the recQl4A mutant seedlings were found to be hypersensitive to UV light and MMS, and more resistant to mitomycin C. The average frequency of intrachromosomal HR in recQl4A mutant plants was increased 7.5-fold over that observed in wild-type plants. The data reveal roles for Arabidopsis RecQl4A in maintenance of genome stability by modulation of the DNA damage response and suppression of HR.

Diabetes mellitus, microalbuminuria, and subclinical cardiac disease: Identification and monitoring of individuals at risk of heart failure

Background-Patients with type 2 diabetes mellitus and elevated urinary albumin:creatinine ratio (ACR) have increased risk of heart failure. We hypothesized this was because of cardiac tissue changes rather than silent coronary artery disease. Methods and Results-In a case-controlled observational study 130 subjects including 50 ACR+ve diabetes mellitus patients with persistent microalbuminuria (ACR > 2.5 mg/mol in males and > 3.5 mg/mol in females, ≥2 measurements, no previous renin- angiotensin-aldosterone therapy, 50 ACR-ve diabetes mellitus patients and 30 controls underwent cardiovascular magnetic resonance for investigation of myocardial fibrosis, ischemia and infarction, and echocardiography. Thirty ACR+ve patients underwent further testing after 1-year treatment with renin-angiotensin-aldosterone blockade. Cardiac extracellular volume fraction, a measure of diffuse fibrosis, was higher in diabetes mellitus patients than controls (26.1±3.4% and 23.3±3.0% P=0.0002) and in ACR+ve than ACR-ve diabetes mellitus patients (27.2±4.1% versus 25.1±2.9%, P=0.004). ACR+ve patients also had lower E0 measured by echocardiography (8.2±1.9 cm/s versus 8.9±1.9 cm/s, P=0.04) and elevated high-sensitivity cardiac troponin T 18% versus 4% ≥14 ng/L (P=0.05). Rate of silent myocardial ischemia or infarction were not influenced by ACR status. Renin-angiotensin-aldosterone blockade was associated with increased left ventricular ejection fraction (59.3±7.8 to 61.5±8.7%, P=0.03) and decreased extracellular volume fraction (26.5±3.6 to 25.2±3.1, P=0.01) but no changes in diastolic function or high-sensitivity cardiac troponin T levels. Conclusions-Asymptomatic diabetes mellitus patients with persistent microalbuminuria have markers of diffuse cardiac fibrosis including elevated extracellular volume fraction, high-sensitivity cardiac troponin T, and diastolic dysfunction, which may in part be reversible by renin-angiotensin-aldosterone blockade. Increased risk in these patients may be mediated by subclinical changes in tissue structure and function

Attosecond electron spectroscopy using a novel interferometric pump-probe technique

We present an interferometric pump-probe technique for the characterization of attosecond electron wave packets (WPs) that uses a free WP as a reference to measure a bound WP. We demonstrate our method by exciting helium atoms using an attosecond pulse with a bandwidth centered near the ionization threshold, thus creating both a bound and a free WP simultaneously. After a variable delay, the bound WP is ionized by a few-cycle infrared laser precisely synchronized to the original attosecond pulse. By measuring the delay-dependent photoelectron spectrum we obtain an interferogram that contains both quantum beats as well as multi-path interference. Analysis of the interferogram allows us to determine the bound WP components with a spectral resolution much better than the inverse of the attosecond pulse duration.Comment: 5 pages, 4 figure