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Microphotoluminescence studies of AlGaO-based asymmetric waveguide microdisk structures incorporating a single sheet of self-organized InAs quantum dots (QD) under photoexcitation are performed. The authors have observed a strong redshift and broadening of the QD optical transition energy at high excitation densities due to excitation-density-induced overheating and many-particle effects and monitored the impact of these effects on the whispering gallery modes (WGMs) in spontaneous and stimulated emission regimes. They have observed strongly nonmonotonic dependencies of the linewidth and intensity of the WGMs with excitation density increase and underline possible reasons for the observed behavior.

An InGaAs submonolayer (SML) quantum-dot photonic-crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fiber-optic applications is demonstrated for the first time. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate depositions of InAs (

On the basis of data in the literature and calculations carried out by the present authors of the KLn X-ray transitions in Si, S and Cl atoms of heavy ion-excited molecules, the main factors determining the formation of such spectra for the third period elements have been clarified. It has been demonstrated that in analysing the experimental values of KLn line energies it is necessary to take into account the effects of atomic and extra-atomic relaxation, multiplet effects and the possible ionisation of the outer electron shells of target atoms. A simple technique of treating X-ray satellites of multiple ionisation has been developed and tested. This technique allows one to determine from experimental spectra the contribution of extra-atomic relaxation effects to the chemical shifts of KLn lines. These data can be used for analysing the tendencies of changes in the electron polarisability of the substance.

The RBE of protons has been investigated on the external beam of the proton accelerator, specially adjusted to clinical use. 137 Cs was used as a standard for comparison. The mean flux of particles in the proton beam was 2-10 8 protons cm 2 in each 1 -6 /xs pulse, delivering a dose of about 20 rads in the plateau region of the curve and 80 rads at the Bragg peak, the relative height of the latter being 4. The RBE of 90 MeV protons ranged from 0-75 for the survival of HeLa cells to 0-68 for the survival of Chinese hamster cells. The RBE determined by the abnormal anaphase scoring technique showed a value of 0-77 for hamster cells. The biological effectiveness of proton irradiation in the Bragg peak (mean energy 8 MeV) in comparison to the plateau region was found to be l-44±0-08 as estimated on the basis of clone formation and 1-85^0-15 on the basis of the induction of chromosome aberrations. Some data concerning the absorbed dose determination for cells irradiated at the boundary between the glass and the nutrient media are discussed. There has recently been considerable interest in the use of accelerated protons for radiotherapy (Lawrence, 1967; Larsson, 1967). For this reason it is important to determine the relative biological efficiency (RBE) of these charged particles. The RBE of proton beams has been investigated thoroughly in the plateau region of the Bragg curve (Jarmonenko and Konoplannikov, 1965). The RBE in the peak region has been determined in a limited number of experiments (Larsson and Kihlman, 1960; Sweet et al., 1967). We have used HeLa and Chinese hamster cells to measure the RBE of the proton beam from the synchrotron which has been specially adapted to medical use. MATERIALS AND METHODS Cell culture technique HeLa cells and Chinese hamster cell line B-lld-ii-FAF-28, clone number 431, were grown in monolayer culture and cell survival was estimated by their clone-forming ability. Monodispersed cells were explanted in glass Carrel flasks of 6 cm diameter containing 6 ml. of medium. The flasks were incubated at 37°C with 5 per cent CO2 in air for three hours, and then rubber stoppers were substituted for cotton plugs. This procedure helped to keep the pH of the medium at a constant level during transportation and irradiation of the cells. The irradiation was performed four to seven hours after explanting. During this period the radiosensitivity of the cells was found to be constant, in good agreement with other findings (Barendsen and Walter, 1964). In the experiments in which cells were irradiated in the Bragg peak region they were kept in Carrel flasks with a thin Mylar film bottom. For the analysis of chromosomal aberrations Chinese hamster cells were grown on thin Mylar sheets of the dimensions of smaller Carrel flasks. Seven to eight hours after irradiation the cells were fixed and stained by aceto-orcein. Cells with bridges and acentric fragments were countered during late

The X-ray absorption K-spectra of chlorine were investigated in gaseous and solid Cl2, HCl, CCl4, and CHCl3. The first absorption peak does not undergo any changes on passing from the gaseous to the crystalline state, while the group of maxima with lower wavelength undergoes extremely substantial changes. It is proposed that in both the gas and the crystal the first maximum indicates a transition of the K-electron to an antibonding molecular orbital containing the 3px-orbital of chlorine, while the short-wavelength region for the solid state indicates the presence of wide energy bands in the crystal.

The introduction of anthropogenic sounds into the marine environment can impact some marine mammals. Impacts can be greatly reduced if appropriate mitigation measures and monitoring are implemented. This paper concerns such measures undertaken by Exxon Neftegas Limited, as operator of the Sakhalin-1 Consortium, during the Odoptu 3-D seismic survey conducted during 17 August’ September 2001. The key environmental issue was protection of the critically endangered western gray whale (Eschrichtius robustus), which feeds in summer and fall primarily in the Piltun feeding area off northeast Sakhalin Island. Existing mitigation and monitoring practices for seismic surveys in other jurisdictions were evaluated to identify best practices for reducing impacts on feeding activity by western gray whales. Two buffer zones were established to protect whales from physical injury or undue disturbance during feeding. A 1 km buffer protected all whales from exposure to levels of sound energy potentially capable of producing physical injury. A 4’ km buffer was established to avoid displacing western gray whales from feeding areas. Trained Marine Mammal Observers (MMOs) on the seismic ship Nordic Explorer had the authority to shut down the air guns if whales were sighted within these buffers. Additional mitigation measures were also incorporated: Temporal mitigation was provided by rescheduling the program from June–August to August–September to avoid interference with spring arrival of migrating gray whales. The survey area was reduced by 19% to avoid certain waters

In 2001’003, >60,000 km of aerial surveys and 7,700 km of vessel surveys were conducted during June to November when critically endangered Korean–Okhotsk or western gray whales (Eschrichtius robustus) were present off the northeast coast of Sakhalin Island, Russia. Results of surveys in all years indicated gray whales occurred in predominantly two areas, (1) adjacent to Piltun Bay, and (2) offshore from Chayvo Bay, hereafter referred to as the Piltun and offshore feeding areas. In the Piltun feeding area, the majority of whales were observed in waters shallower than 20 m and were distributed from several hundred meters to ∼ 5 km from the shoreline. In the offshore feeding area during all years, the distribution of gray whales extended from southwest to northeast in waters 30’5 m in depth. During all years, the distribution and abundance of whales changed in both the Piltun and offshore feeding areas, and both north–south and inshore–offshore movements were documented within and between feeding seasons. The discovery of a significant number of whales feeding in the offshore area each year was a substantial finding of this study and raises questions regarding western gray whale abundance and population levels, feeding behavior and ecology, and individual site-fidelity. Fluctuations in the number of whales observed within the Piltun and offshore feeding areas and few sightings outside of these two areas indicate that gray whales move between the Piltun and offshore feeding areas during their summer–fall feeding season. Seasonal shifts in the distribution and abundance of gray whales between and within both the Piltun and offshore feeding areas are thought, in part, to be a response to seasonal changes in the distribution and abundance of prey. However, the mechanism driving the movements of whales along the northeast coast of Sakhalin Island is likely very complex and influenced by a multitude of factors.

Exxon Neftegas Limited, as operator of the Sakhalin-1 consortium, is developing oil and gas reserves on the continental shelf off northeast Sakhalin Island, Russia. DalMorNefteGeofizika (DMNG) on behalf of the Sakhalin-1 consortium conducted a 3-D seismic survey of the Odoptu license area during 17 August-9 September 2001. A portion of the primary feeding area of the endangered western gray whale (Eschrichtius robustus) is located in the vicinity of the seismic survey. This paper presents data to assess whether western gray whale bottom feeding activity, as indicated by visible mud plumes, was affected by seismic operations. The mitigation and monitoring program associated with the seismic survey included aerial surveys during 19 July-19 November 2001. These aerial surveys documented the local and regional distribution, abundance, and bottom feeding activity of western gray whales. Data on gray whale feeding activity before, during and after the seismic survey were collected, with the whales assumed to be feeding on the benthos if mud plumes were observed on the surface. The data were used to assess the influence of seismic survey and other factors (including environmental) on feeding activity of western gray whales. A stepwise multiple regression analysis failed to find a statistically significant effect (alpha = 0.05) of the seismic survey on frequency of occurrence of mud plumes of western gray whales used as a proxy to evaluate bottom feeding activity in Piltun feeding area. The regression indicated that transect number (a proxy for water depth, related to distance from shore) and swell height (a proxy for sea state) were the only variables that had a significant effect on frequency of whale mud plumes. It is concluded that the 2001 seismic survey had no measurable effect (alpha = 0.05) on bottom feeding activity of western gray whales off Sakhalin Island.

Since 1969 proton beam therapy of patients with different types of diseases using the ITEP synchrotron proton beam with the energy up to 200 MeV has been conducted in a number of Moscow medical centers. These irradiations employing a specially formed beam are used on a routine basis and are performed in parallel with the program of physical research. Two additional channels as well as two new procedure rooms have been in operation since 1982. A special setup of equipment including clinical dosimetry devices, equipment for patients' irradiation (4 special units), and computer-controlled systems have been installed at the facility. By the present time over 1300 patients have been irradiated. The authors describe physical and dosimetric equipment and irradiation techniques. A summary table containing data on the patients is provided.

A two-dimensional photonic crystal with hexagonal lattice of air-holes is patterned into an active planar waveguide containing InAs / InGaAs quantum dots. Variable-angle reflectivity spectroscopy is used to map out the photonic band structure. Fano-type resonances observed in the measured reflectivity spectra in TE (TM) polarizations along the Γ–K (Γ–M) lattice direction are attributed to resonance coupling of the optically active photonic bands to external light. Angle-resolved photoluminescence measurements are shown to trace the band structure of the leaky mode. The revealed three-fold emission intensity enhancement of photonic crystals is ascribed to both Purcell and Bragg scattering effects.

We report near-temperature-insensitive, highly linear oxide-confined directly modulated 850 nm-range VCSEL chips and fiber-coupled subassemblies operating up to 40 Gbit/s at < 10 kA/cm2 with a rise-time < 10 ps at up to 100°C.