Blue Field Research Articles

Use of imaging spectroscopy, fiber optic reflectance spectroscopy, and X-ray fluorescence to map and identify pigments in illuminated manuscripts

A paradigm using multispectral visible and near-infrared imaging spectroscopy is presented to semi-automatically create unbiased spectral maps that guide the site selection for in situ analytical methods (e.g. fiber optic reflectance spectroscopy and X-ray fluorescence) in order to identify and map pigments in illuminated manuscripts. This approach uses low spectral resolution imaging spectroscopy to create maps of areas having the same spectral characteristics. This paradigm is demonstrated by analysis of the illuminated manuscript leaf Christ in Majesty with Twelve Apostles (workshop of Pacino di Buonaguida, c. 1320). Using this approach the primary pigments are mapped and identified as azurite, lead-tin yellow, red lead, a red lake (likely insect-derived), a copper-containing green, brown iron oxide, and lead white. Moreover, small amounts of natural ultramarine were found to be used to enhance the blue fields around Christ, and a red lake was used to highlight different colors. These results suggest that the proposed paradigm offers an improved approach to the comprehensive study of illuminated manuscripts by comparison with site-specific analytical methods alone. The choice of broad spectral bands proves successful, given the limited palette in illuminated manuscripts, and permits operation at the low light intensity required for examination of manuscripts.

THE BLISS OF SOLITUDE

7 1 R T H E B L I S S O F S O L I T U D E J U L I A N G E W I R T Z A Poet could not but be gay In such a laughing company . . . – William Wordsworth In my left hand he was a burning rope. All day long this air was thin as the smile of quartered mangoes or the glow of his skin in my nightlight – And all day long I was speaking past tall wheat to the sycamore tree in the perpetually blue field I remember a boy climbing up hollering as the sky filled from the top with that dark sinking like cold smoke into the city Tonight the meadow is laughing again while a kit of jacobins mulls in wire cages sleeping inside the fantails of their collars and in that garden an old man in his green silk pajamas stitched with fishermen angling silver rivers wraps his arms around the moonlight falling on a thin wool blanket – Waxing moon, half-weighted hammock. ...

Population Dynamics ofScyphophorus acupunctatus(Coleoptera: Curculionidae) on Blue Agave

The agave weevil, Scyphophorus acupunctatus Gyllenhal, is considered the main pest of Agave tequilana Weber var. 'Azul' (Asparagales: Asparagaceae) in Mexico. In this study, we investigated the population fluctuations of S. acupunctatus for 19 months using 2 sampling methods in blue agave fields in Ahualulco and Amatitan, Jalisco, Mexico. We recorded the direct damage caused by weevils on the sampled agave plants and evaluated the correla- tion between the number of S. acupunctatus captured by pheromone traps and the density of weevils located on plants. In Ahualulco, the highest agave weevil population density (for all developmental stages) was detected in Mar 2008, although the peak of trap captures occurred in May 2009. In Amatitan, the highest agave weevil population density was ob- served in Apr 2009, and the highest number of insects was captured in May and Sep 2009. The mean fraction of necrotic bole tissue caused by the weevils per sampled plant was 75.4 ± 2.1% and 72.6 ± 2.0% in Ahualulco and Amatitan, respectively. In Ahualulco, there was a positive correlation between the number of weevils caught in the pheromone traps and the number of adult weevils on the plants, whereas the number of weevils caught by the pheromone traps at Amatitan was positively correlated with the total number of weevils on the plants. We found that the sex ratio of weevils recovered from agave plants was approxi- mately 1:1 at both experimental sites, and this trend did not vary seasonally; conversely, the sex ratio of captured weevils in pheromone traps was female-biased year-round.

The evolution of dust-obscured star formation activity in galaxy clusters relative to the field over the last 9 billion years★

We compare the star formation (SF) activity in cluster galaxies to the field from z=0.3-1.5 using $Herschel$ SPIRE 250$\mu$m imaging. We utilize 274 clusters from the IRAC Shallow Cluster Survey (ISCS) selected as rest-frame near-infrared overdensities over the 9 square degree Bootes field . This analysis allows us to quantify the evolution of SF in clusters over a long redshift baseline without bias against active cluster systems. Using a stacking analysis, we determine the average star formation rates (SFRs) and specific-SFRs (SSFR=SFR/M$_{\star}$) of stellar mass-limited (M>1.3x10$^{10}$ M$_{\odot}$), statistical samples of cluster and field galaxies, probing both the star forming and quiescent populations. We find a clear indication that the average SF in cluster galaxies is evolving more rapidly than in the field, with field SF levels at z>1.2 in the cluster cores (r<0.5 Mpc), in good agreement with previous ISCS studies. By quantifying the SF in cluster and field galaxies as an exponential function of cosmic time, we determine that cluster galaxies are evolving ~2 times faster than the field. Additionally, we see enhanced SF above the field level at z~1.4 in the cluster outskirts (r>0.5 Mpc). These general trends in the cluster cores and outskirts are driven by the lower mass galaxies in our sample. Blue cluster galaxies have systematically lower SSFRs than blue field galaxies, but otherwise show no strong differential evolution with respect to the field over our redshift range. This suggests that the cluster environment is both suppressing the star formation in blue galaxies on long time-scales and rapidly transitioning some fraction of blue galaxies to the quiescent galaxy population on short time-scales. We argue that our results are consistent with both strangulation and ram pressure stripping acting in these clusters, with merger activity occurring in the cluster outskirts.

Male wing color properties predict the size of nuptial gifts given during mating in the Pipevine Swallowtail butterfly (Battus philenor)

In many animals, males bear bright ornamental color patches that may signal both the direct and indirect benefits that a female might accrue from mating with him. Here we test whether male coloration in the Pipevine Swallowtail butterfly, Battus philenor, predicts two potential direct benefits for females: brief copulation duration and the quantity of materials the male passes to the female during mating. In this species, males have a bright iridescent blue field on the dorsal hindwing surface, while females have little or no dorsal iridescence. Females preferentially mate with males who display a bright and highly chromatic blue field on their dorsal hindwing. In this study, we show that the chroma of the blue field on the male dorsal hindwing and male body size (forewing length) significantly predict the mass of material or spermatophore that a male forms within the female's copulatory sac during mating. We also found that spermatophore mass correlated negatively with copulation duration, but that color variables did not significantly predict this potential direct benefit. These results suggest that females may enhance the material benefits they receive during mating by mating with males based on the coloration of their dorsal hindwing.

Simulation study of CO2 sequestration potential of the Mary Lee coal zone, Black Warrior basin

Significant potential exists for CO2 sequestration in coalbed methane reservoirs of the Black Warrior basin. Reservoir simulation is an appropriate approach to estimate both the storage capacity and methane recovery enhancement. However, prior to a reliable reservoir modeling and simulation, conducting an accurate and comprehensive reservoir characterization study is necessary. The purpose of the present study is twofold: (a) to provide a rigorous reservoir characterization study required for modeling Mary Lee coal group in the Blue Creek field of the Black Warrior basin; (b) to run fluid flow simulations to predict the performance of ECBM process applied to an under pressured zone of the Mary Lee coal group. According to the current well configuration of Blue Creek field, three applicable well patterns, namely a direct line drive, an inverted 5-spot and a normal 5-spot were separately (i.e., in three distinct cases) used for simulating ECBM. Simulations were run on an approximately 32 ha (80-acre) drainage area, and included coal matrix shrinkage/swelling effects. The injected gas was assumed to be pure CO2. Using an inverted 5-spot pattern, simulations predicted that after 7.5 years of CO2 injection, approximately 32,000 tonnes of CO2 would be sequestered per 32 ha of this zone and that methane recovery would be enhanced by 36 %. Using a normal 5-spot pattern, CO2 breakthrough would occur 2.4 years earlier, and about 40,000 tonnes CO2 would be sequestered. However, methane production would be enhanced by 33 %. Considering methane recovery enhancement, direct line drive pattern delivered poor results in comparison with two other patterns. As expected, the results also showed that CO2 injection would increase water production.

Ram pressure and dusty red galaxies – key factors in the evolution of the multiple cluster system Abell 901/902

We present spectroscopic observations of 182 disk galaxies (96 in the cluster and 86 in the field environment) in the region of the Abell 901/902 multiple cluster system, which is located at a redshift of $z\sim 0.165$. The presence of substructures and non-Gaussian redshift distributions indicate that the cluster system is dynamically young and not in a virialized state. We find evidence for two important galaxy populations. \textit{Morphologically distorted galaxies} are probably subject to increased tidal interactions. They show pronounced rotation curve asymmetries at intermediate cluster-centric radii and low rest-frame peculiar velocities. \textit{Morphologically undistorted galaxies} show the strongest rotation curve asymmetries at high rest-frame velocities and low cluster-centric radii. Supposedly, this group is strongly affected by ram-pressure stripping due to interaction with the intra-cluster medium. Among the morphologically undistorted galaxies, dusty red galaxies have particularly strong rotation curve asymmetries, suggesting ram pressure is an important factor in these galaxies. Furthermore, dusty red galaxies on average have a bulge-to-total ratio higher by a factor of two than cluster blue cloud and field galaxies. The fraction of kinematically distorted galaxies is 75% higher in the cluster than in the field environment. This difference mainly stems from morphological undistorted galaxies, indicating a cluster-specific interaction process that only affects the gas kinematics but not the stellar morphology. Also the ratio between gas and stellar scale length is reduced for cluster galaxies compared to the field sample. Both findings could be best explained by ram-pressure effects.

Retinal white blood cell flux and systemic blood pressure in patients with type 1 diabetes

There is evidence that altered retinal blood flow and altered retinal blood flow regulation play a role in the development and progression of diabetic retinopathy. We compared the association between systemic blood pressure and retinal white blood cell flux in patients with type 1 diabetes and healthy control subjects. The study was performed in 100 patients with type 1 diabetes with no or minimal diabetic retinopathy and a group of 313 age-matched healthy controls. Inclusion criteria were systolic blood pressure ≤ 160 mmHg and diastolic blood pressure ≤ 95 mmHg. None of the subjects took vasoactive medication except insulin. The blue field entoptic technique was used to assess retinal white blood cell flux, velocity and density in the perimacular region. Pressure-flow relationships were calculated for both groups to assess differences in blood flow regulation. Retinal white blood cell flux was comparable between the two study groups. Both type 1 diabetic patients and healthy subjects showed a significant positive correlation between retinal white blood cell flux and mean arterial pressure (diabetic patients: r=0.48; p<0.05, healthy subjects r=0.28). The correlation coefficients between mean arterial pressure and white blood cell flux were significantly higher in patients with diabetes than in the healthy control group (p=0.0459). Retinal white blood cell flux, as assessed with the blue-field entoptic technique, is not significantly different between type 1 diabetic patients with no or minimal retinopathy and healthy control subjects. Type 1 diabetic subjects do, however, show an abnormal association between systemic blood pressure and retinal white blood cell flux. This indicates altered autoregulation in early diabetic retinopathy.

Supplementary Blue and Red Radiation at Sunrise and Sunset Influences Growth of Ageratum, African Marigold, and Salvia Plants

BACKGROUND: Light-emitting diodes (LEDs) with lower electric cost and the specific wavelength have been considering as a novel light source for plant production in greenhouse conditions as well as in a closed culture system. Supplementary lighting for day-length extension was considered as light intensity, light quality, and/or photoperiod control on plant growth and development. Effects of supplementary blue or red LED radiation with lower light intensity on growth of Ageratum (Ageratum houstonianum Mill., cv. Blue Field), African marigold (Tagetes erecta L., cv. Orange Boy), and Salvia (Salvia splendens F. Sello ex Ruem & Schult., cv. Red Vista) were discussed during sunrise and sunset twilight in the experiment. METHODS AND RESULTS: Supplementary lighting by blue and red LEDs for 30 (Treatment B30; R30) or 60 (Treatment B60; R60) min. per day were established in greenhouse conditions. Photosynthetic photon flux for supplementary radiation was kept at 15 μmol m-2 s-1 on the culture bed. Natural condition without supplementary light was considered as a control. The highest shoot and root dry weights were shown in African marigold exposed by red light for 60 min. per day. Supplementary blue and red lighting regardless of the radiation time significantly stimulated development of lateral branches in African marigold. Stem growth in Ageratum and Salvia seedlings was significantly promoted by red radiation as well as natural light. CONCLUSIONS: Extending of the radiation time at sunrise and sunset twilight using LEDs stimulated reproductive growth of flowering plant species. Different characteristics on growth under supplementary blue or red lighting conditions were also observed in the seedlings during supplementary radiation.

CFHT Legacy Ultraviolet Extension (CLUE): witnessing galaxy transformations up to 7 Mpc from rich cluster cores

Using the optical data from the Wide component of the CFHT Legacy Survey, and new ultraviolet data from GALEX, we study the colours and specific star formation rates (SSFR) of ~100 galaxy clusters at 0.16<z<0.36, over areas extending out to radii of r~7Mpc. We use a multicolour, statistical background subtraction method to study the galaxy population at this radius; thus our results pertain to those galaxies which constitute an excess over the average field density. We find that the average SSFR, and its distribution, of the star-forming galaxies (with SFR>0.7 M_sun/yr at z~0.2 and SFR>1.2 M_sun/yr at z~0.3) have no measurable dependence on the cluster-centric radius, and are consistent with the field values. However, the fraction of galaxies with SFR above these thresholds, and the fraction of optically blue galaxies, are lower for the overdense galaxy population in the cluster outskirts compared with the average field value, at all stellar masses M*>10^{9.8} M_sun and at all radii out to at least 7Mpc. Most interestingly, the fraction of blue galaxies that are forming stars at a rate below our UV detection limit is much higher in all radial bins around our cluster sample, compared with the general field value. This is most noticeable for massive galaxies M*>10^{10.7} M_sun; while almost all blue field galaxies of this mass have detectable star formation, this is true for less than 20% of the blue cluster galaxies, even at 7Mpc from the cluster centre. Our results support a scenario where galaxies are pre-processed in locally overdense regions, in a way that reduces their SFR below our UV detection limit, but not to zero.

Arthur Morrison, Criminality, and Late-Victorian Maritime Subculture

In 1897, the literary critic H. D. Traill accused Arthur Morrison’s novel, <em>A Child of the Jago</em>, of exaggerating the viciousness of East London’s poor, claiming that Morrison had distilled various criminal behaviors into one totalizing, nightmarish zone of barbarity. This essay looks to Morrison’s later novel, <em>The Hole in the Wall</em> (1902), whose concentration of crime is more ambiguous. Morrison tells the reader that Blue Gate Fields, and the pub within it, Paddy’s Goose, are especial locales of danger, but in fact, criminality extends beyond them to wider Wapping, including the pub and home of Captain Nat Kemp and his grandson, the narrator Stephen Kemp. Through his portrayal of Wapping, Morrison conveys his childhood familiarity with the specific maritime culture of the docks and their associated industries. In this regard, we can classify Morrison not merely as an East End novelist, but as a docklands writer. He recognized the unusual topography of Wapping with its sailors’ pubs, lodging houses, and curio shops – and also the hazards inherent there for the sailor on leave: the risk of losing one’s freedom and wages to predatory crimps and ‘land sharks’. Given his commitment to representing the district with all of its idiosyncrasies, Morrison reminds us of the limits of generalizing the ‘East End’ as a homogenous region.

PHOTOMETRIC CHARACTERIZATION OF THE GALACTIC STAR CLUSTER TRUMPLER 20

We present deep UBVI photometry for Trumpler 20, a rich, intermediate-age open cluster located at l = 30147, b = +222 (α = 12h39m34s, δ = −60°37'00'', J2000.0) in the fourth Galactic quadrant. In spite of its interesting properties, this cluster has received little attention, probably because the line of sight to it crosses the Carina spiral arm twice (and possibly also the Scutum-Crux arm), which causes significant contamination of its color–magnitude diagram (CMD) by field stars, therefore seriously complicating its interpretation. In this paper, we provide more robust estimates of the fundamental parameters of Trumpler 20 and investigate the most prominent features of its CMD: a rich He-burning star clump, and a vertical sequence of stars above the turnoff, which can be either blue stragglers or field stars. Our precise photometry, in combination with previous investigations, has allowed us to derive updated values of the age and heliocentric distance of Trumpler 20, which we estimate to be 1.4 ± 0.2 Gyr and 3.0 ± 0.3 kpc, respectively. As predicted by models, at this age the clump has a tail toward fainter magnitudes and bluer colors, thus providing further confirmation of the evolutionary status of stars in this particular phase. The derived heliocentric distance places the cluster in the inter-arm region between the Carina and Scutum arms, which naturally explains the presence of the vertical sequence of stars (which was originally interpreted as the cluster itself) observed in the upper part of the CMD. Most of these stars would therefore belong to the general galactic field, while only a few of them would be bona fide cluster blue stragglers. Our data suggest that the cluster metallicity is solar and its reddening is E(B − V) = 0.35 ± 0.04. Finally, we believe we have solved a previously reported inconsistency between the spectroscopic temperatures and colors of giant stars in the cluster.

Metal and metalloid bioaccumulation in the Pacific blue shrimp Litopenaeus stylirostris (Stimpson) from New Caledonia: Laboratory and field studies

The present work aimed at better understanding metal and metalloid bioaccumulation in the edible Pacific blue shrimp Litopenaeus stylirostris, using both laboratory and field approaches. In the laboratory, the bioaccumulation kinetics of Ag, Cd, Co, Cr, and Zn have been investigated in shrimp exposed via seawater and food, using the corresponding γ-emitting radiotracers (110mAg, 109Cd, 57Co, 51Cr, and 65Zn) and highly sensitive nuclear detection techniques. Results showed that hepatopancreas and intestine concentrated the metals to the highest extent among the blue shrimp organs and tissues. Moulting was found to play a non negligible detoxification role for Co, Cr and, to a lesser extent, Zn. Metal retention by L. stylirostris widely varied (from a few days to several months), according to the element and exposure pathway considered (a given metal was usually less strongly retained when ingested with food than when it was taken up from the dissolved phase). In the field study, Ag, As, Cd, Co, Cr, Cu, Mn, Ni, and Zn were analysed in shrimp collected from a New Caledonian aquaculture pond. Metal concentrations in the shrimp muscles were generally relatively low and results confirmed the role played by the digestive organs and tissues in the bioaccumulation/storage/detoxification of metals in the Pacific blue shrimp. Preliminary risk considerations indicate that consumption of the shrimp farmed in New Caledonia is not of particular concern for human health.

Twelve‐hour reproducibility of retinal and optic nerve blood flow parameters in healthy individuals

The aim of the present study was to investigate the reproducibility and potential diurnal variation of optic nerve head and retinal blood flow parameters in healthy individuals over a period of 12 hr. We measured optic nerve head and retinal blood flow parameters in 16 healthy male non-smoking individuals at five time-points during the day (08:00, 11:00, 14:00, 17:00 and 20:00 hr). Outcome parameters were perimacular white blood cell flux (as assessed with the blue field entoptic technique), blood velocities in retinal veins (as assessed with bi-directional laser Doppler velocimetry), retinal arterial and venous diameters (as assessed with the retinal vessel analyser), optic nerve head blood flow, volume and velocity (as assessed with single point and scanning laser Doppler flowmetry) and blood velocities in the central retinal artery (as assessed with colour Doppler imaging). The coefficient of variation and the maximum change from baseline in an individual were calculated for each outcome parameter. No diurnal variation in optic nerve head or retinal blood flow was observed with any of the techniques employed. Coefficients of variation were between 1.6% and 18.5% for all outcome parameters. The maximum change from baseline in an individual was much higher, ranging from 3.7% to 78.2%. Our data indicate that in healthy individuals the selected techniques provide adequate reproducibility to be used in clinical studies. However, in patients with eye diseases and reduced vision the reproducibility may be considerably worse.

Most readily usable methods to measure ocular blood flow

Abstract Purpose SIS Lecture. Methods Literature search. Results Ocular Blood Flow Research Association (OBFRA, recently merged with another organization ‐ ISOCO, into one single Association for Ocular CDirculation ‐ AOC) made a significant contribution to standardization of the blood flow measuring techniques in the field of ophthalmology. A consens was reached on the number of OBF measurements techniques that occured in the past decades. Particular emphasis was placed on the basic technology, specific parameters and interpretation, accuracy and reproducibility, field of clinical applications. Open questions were extensively discussed, limits of each technique clearly postulated. and a consensus statement put together for each of the technique involved. It encompassed techniques like color Doppler imaging, laser Doppler flowmetry (continuous as well as scanning LDF), laser Doppler velocimetry, Retinal Vessel Analyzer, combination of the vessel diameter measurement and the LDV, laser interferometry of the fundus pulsations amplitude, retinal oxymetry, measurements of the pulsatile component of the blood flow, blue field entoptic method and the newest ‐ Doppler OCT. Conclusion There is no overwhelming measuring technique able to cover all the aspects of the research and the daily clinical routine. Various parameters and various vascular beds are involved, which makes the interpretation of the obtained results strenuous. Of particular importance is the capability of OBF measuring techniques to capture one dynamic feature of ocular circulation ‐ its ability to regulate and to response to various challenges. It is widely believed that not the constantly reduced blood flow, but rather the lack of regulation thereof, leads to prevalent ocular diseases.

A non-destructive digital imaging method to predict immobilized yeast-biomass

In food fermentation, many types of immobilization systems are used, such as hydrogel entrapment, where alginate is the main biopolymer. One of the important problems in industrial processes is the quantifications of biomass, since the traditional system of direct cell counting cannot be used. In this study, a simple digital imaging method to determine the biomass of yeasts immobilized into alginate capsules was developed. Important evidence of the yeasts growing inside the alginate was the change in the surface color of the capsule. Digital images were taken with different biomass concentration, and the RGB-analysis showed significant differences in the blue field. The histogram of the blue channel was used to develop a PLS multivariate calibration to predict biomass concentration. The method was validated in primary beer fermentation with good efficiency.

Manufacture of Dye-Sensitized Nano Solar Cells and their I-V Curve Measurements

The article presents a manufacturing process and their I-V curves measurements of the dye-sensitized nano solar cells (DSSCs). The constituents of the produced DSSCs are the photoelectrode, the dyes, the electrolyte, and the counter electrode. In process the constituents are prepared for assembling individually. Four pieces of slight glass spacers around the cell edges are sandwiched between the photoelectrode and the counter electrode to build a gap. The gap is then filled in the liquid electrolyte, which is finished by mixing 0.5M KI and 0.05M I2 in solvent with ethylenecarbonate and propylenecarbonate in a 1 : 9 volume ratio. An instrument for measurements of photoelectric conversion efficiency and a scanning absorption spectrum analyzer, which used a metal halide lamp as the light source due to its better fitted spectrum with the solar spectrum on purple and blue fields, are built in this work.

Results from the Greenland Search for Meteorites expedition

Abstract— Following discoveries of blue ice areas in Greenland resembling meteorite‐bearing blue ice fields in Antarctica, a surface search of several of the most promising sites was carried out in August 2003. The ice fields are located in Kong Christian X Land, in northeastern Greenland around 74°N at elevations between 2100 and 2400 m. No meteorites were found in any of the localities that were searched. Evidence of occasional significant melting (filled crevasses and melt sheets) suggest that summer temperatures are sometimes high enough that dark rocks, like meteorites, can melt through the upper layers of ice. Small terrestrial rocks and cryogenite were found down to 50 cm below the ice surface. Meter‐sized terrestrial rocks were found on top of the ice downstream from nunataks. These rocks shade the ice below, and since they were apparently too massive to warm up during warm days, they remained at the surface as the surrounding ice ablated away. Our findings strongly suggest that Greenland is currently unlikely to harbor significant meteorite concentrations on blue ice fields.

SU‐FF‐T‐178: Dosimetric Evaluation of Penumbra for Conformal and Intensity Modulated Radiotherapy

Purpose: To evaluate the penumbral characteristics as function of collimation systems, conventional detector, depth, energy and MLC travel orientations using diode detectors. Methods and Materials: The experiment was carried out in a Clinac 2300C/D linear accelerator for 6 and 15 MV. For penumbral width determination, cross‐beam profiles were measured using Blue phantom radiation field analyzer, 0.13cm3 ionchamber and diode detectors, CU‐500E dual‐channel electrometer and OmniPro beam‐data acquisition system. The penumbra was measured for both Jaw and MLC‐defined field sizes of 4×4 to 30×30cm2 depths at dmax, 5, 10, 15 and 20cm and also for cross‐plane and in‐plane MLC travel orientations at 100cm SSD. The penumbra width was calculated as the distance between 80%–20% intensity in the profiles. Results: The MLC penumbra was in the range of 3.6mm to 4mm for 6MV and 5.4mm to 7.1mm for 15MV at dmax depth for field sizes of 4×4 to 30×30cm2 as measured by diode detector. The mean differences between Jaw and MLC‐defined field's penumbra were 0.8mm ± 0.2, and 1mm ± 0.2 for 6MV and 1.2mm ±0.2 and 1.8mm ±0.5 for 15MV at dmax and 10cm depths. The maximum difference of 1.9mm ±0.3 for 6MV and 2.2mm ±0.2 for 15MV between diode and 0.13cm3 detectors were found. Use of diode detectors, maximum differences of 3.4mm ±3 at 20cm depths between energies and the differences of 3.3mm ± 2.2 for 6 MV and 1.2mm ± 0.3 for 15MV between cross‐plane and in‐plane MLC penumbra were found. Conclusions: The rounded‐end MLC penumbra was larger as compared to Jaw penumbra. The penumbra measured by diode was increasing with energy upto a certain depths and field sizes and then it increases more with low‐energy at larger depths and field sizes as compared to high‐energy. The adequate accounting of penumbra is important in intensity modulated beam dose calculation.

Micrometeorites from Central Antarctic snow: The CONCORDIA collection

We recovered micrometeorites from surface snow layers near the French-Italian station CONCORDIA. The unique weather and isolation conditions of Dome C allowed us to recover micrometeorites that are much better preserved than those extracted from blue ice fields. We have identified a new population of friable fine-grained micrometeorites; the absence of such particles in previous collections can be explained by their destruction by mechanical processes. In contrast to previous collections of micrometeorites, the particles from CONCORDIA Collection are characterized by a high content of Fe-sulfides and an undepleted CI elemental abundance pattern of their fine-grained matrix. These features suggest that micrometeorites from Dome C snow have endured much lower alteration from terrestrial weathering, unlike the micrometeorites recovered from near the margin of the Antarctic ice sheet (Adélie Land). The CONCORDIA particles have well constrained terrestrial ages and, given the low Dome C precipitation rate, the central regions of Antarctica provide a unique opportunity to search for particles from historical meteor showers.