Ultrafast spin-polarized electron dynamics in the unoccupied topological surface state of Bi2Se3.

The three-dimensional topological insulator Bi2Se3 presents two cone-like dispersive topological surface states centered at the [Formula: see text] point. One of them is unoccupied in equilibrium conditions and located 1.8 eV above the other one lying close to the Fermi level. In this work we employ time- and angle-resolved photoemission spectroscopy with circularly polarized pump photons to selectively track the spin dynamics of the empty topological states. We observe that spin-polarized electrons flow along the topological cone and recombine towards the unpolarized bulk states on a timescale of few tens of femtoseconds. This provides direct evidence of the capability to trigger a spin current with circularly polarized light.

A flexible experimental setup for femtosecond time-resolved broad-band ellipsometry and magneto-optics.

A versatile experimental setup for femtosecond time-resolved ellipsometry and magneto-optical Kerr effect measurements in the visible light range is described. The apparatus is based on the pump-probe technique and combines a broad-band probing beam with an intense near-infrared pump. According to Fresnel scattering matrix formalism, the analysis of the reflected beam at different polarization states of the incident probe light allows one to determine the diagonal and the off-diagonal elements of the dielectric tensor in the investigated sample. Moreover, the pump-probe method permits to study the dynamics of the dielectric response after a short and intense optical excitation. The performance of the experimental apparatus is tested on CrO2 single crystals as a benchmark.

An innovative Yb-based ultrafast deep ultraviolet source for time-resolved photoemission experiments.

Time- and angle-resolved photoemission spectroscopy is a powerful technique to study ultrafast electronic dynamics in solids. Here, an innovative optical setup based on a 100-kHz Yb laser source is presented. Exploiting non-collinear optical parametric amplification and sum-frequency generation, ultrashort pump (hν = 1.82 eV) and ultraviolet probe (hν = 6.05 eV) pulses are generated. Overall temporal and instrumental energy resolutions of, respectively, 85 fs and 50 meV are obtained. Time- and angle-resolved measurements on BiTeI semiconductor are presented to show the capabilities of the setup.

The energy expenditure of female carpet weavers and rural women in Iran.

The energy cost of individual activities and the daily energy expenditure of female carpet weavers and villagers were measured in Iranian villages and in the town of Isfahan as part of a series of studies to assess the validity for the population of past and present FAO recommended energy allowances. The energy cost of typical activities was measured by indirect calorimetry using Max-Planck respirometers. Daily energy expenditure was assessed using these figures combined with a 24-hr activity diary. The results of standard activity values are compared with other published values for Europeans and populations of countries with hot climates. The mean daily energy expenditure for both groups was in the order of 2000 kcal/day, below but close to the FAO recommendations which appear valid for rural women in a large part of the country but are probably an underestimate for areas where the participation of women in agriculture is greater.

The energy expenditure of Iranian agricultural workers.

The energy cost of agricultural and standard activities and the daily energy expenditure of male agricultural workers were measured during different seasons in Iranian villages to assess the validity of past and present Food and Agricultural Organization recommended energy allowances for that population. Studies included low income farmers in a village representative of those around the central desert where harvesting takes place under conditions of extreme summer heat. Measurements were also made during the Moslem fasting period when no food may be eaten between dawn and dusk. Energy cost of typical activities was measured by indirect calorimetry using the Max-Planck respirometer and daily energy expenditure was assessed using these figures combined with a diary of activities throughout the 24-hr period. Results of individual activity values are compared with other published figures. Comparison of daily energy expenditure of fasting subjects and nonfasting after Ramazan showed no significant difference. No significant difference was found between values of standardized activities at high summer temperatures and moderate temperatures. Mean values of daily energy expenditure during winter when activity is low are around 2600 kcal/day and for the other seasons of high activity 3400 kcal/day. These figures suggest that past and present Food and Agricultural Organization standards are low for this population.

Favism, with special reference to Iran.

Fava beans (Vicia fava) are cultivated rather widely in most countries of the Eastern Mediterranean area and provide a cheap but protein-rich food that can be eaten alone, in various culinary preparations, including bread, or as a dietary supplement. However, the ingestion of fava beans may induce a haemolytic disease-favism-in some susceptible individuals and this might appear to limit the use of this pulse crop in those regions where favism occurs frequently. The uses of fava beans in Iran, the characteristics of favism and the present state of knowledge of the pathology of the disease are reviewed in this paper. Although some progress has been made in identifying the toxic substances and in explaining their mode of action, our understanding of favism is still limited. It appears that the disease is seen particularly in young children and is associated with a deficiency of glucose-6-phosphate dehydrogenase (G6PD) in the blood.