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Radiation-induced lung injury remains a significant toxicity in thoracic radiotherapy. Because a precise diagnosis is difficult and commonly used assessment scales are unclear and subjective, there is a need to establish quantitative and sensitive grading methods. The lung tissue density change expressed in Hounsfield units (HUs) derived from CT scans seems a useful numeric surrogate. The study aimed to confirm a dose-response effect on HU value changes (ΔHU), their evolution in time, and the impact of selected clinical and demographic factors. We used dedicated, self-developed software to register and analyze 120 pairs of initial and follow-up CT scans of 47 lung cancer patients treated with dynamic arc radiotherapy. The differences in HU values between CT scans were calculated within discretized dose-bins limited by isodose lines. We have proved the dose-effect relationship, which is well described with a sigmoid model. We found the time evolution of HU changes to suit a typical clinical presentation of radiation-induced toxicity. Some clinical factors were found to correlate with ΔHU degree: planning target volume (PTV), V35 in the lung, patient's age and a history of arterial hypertension, and initial lung ventilation intensity. Lung density change assessment turned out to be a sensitive and valuable method of grading post-RT lung toxicity. [ABSTRACT FROM AUTHOR]

This paper aims at developing a technique for observing the frost heaving process in soil nondestructively and microscopically using an industrial micro-focus X-ray CT scanner. For this purpose, a compact frost heaving apparatus that could freeze the soil in one dimension inside the X-ray CT scanner was developed. This experimental method made it possible to observe the process of ice lens formation in the soil and the shape of the ice lens in detail. In highly frost susceptible weathered volcanic ash, ice lenses like multiple cracks were observed to develop in the early stages of the experiment. When the freezing front was stagnant and the heat was balanced, thick and well-developed ice lenses could be observed. The shape of the ice lens observed in the weathered volcanic ash without gravel was relatively flat. In the terrace deposits containing gravel, ice lenses were observed to be formed from around the larger particles. Furthermore, the formed ice lenses were more uneven in shape than weathered volcanic ash. In the case of volcanic ash sand composed of coarse grains that do not have frost susceptibility, no frost heaving occurred and no ice lenses were observed. The gray levels of the frozen areas of the weathered volcanic ash and terrace deposits with frost susceptibility were found to decrease. This is thought to be because the precipitation of ice lenses in the soil pushed the soil particles apart and reduced their density relatively. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the changes in abundance, species richness, and diversity of epiphytic Gastrotricha in the littoral of a mesotrophic lake. The influence of pH and oxygen on their occurrence was also investigated. Gastrotricha occurred throughout the year: 27 species were identified together, and species richness varied at different seasons. The highest number of species on water vegetation was found in the summer (26 species), while in the winter season only 7 species were present. Species diversity expressed by the Shannon index, in spring, summer, and autumn was high and amounted 2.10, 2.37, and 2.31, respectively. In winter, the value of the index was significantly lower and amounted 0.59. Three species were found to be dominant from spring to autumn with the dominance over 9.0%: Heterolepidoderma macrops Kisielewski, 1981, H. ocellatum (Mecˇnikow, 1865), and Lepidodermella squamata (Dujardin, 1841). The GLM analysis revealed that number of collected species in spring, summer, and autumn does not depend either on season or on pH and oxygen content. The lowest density of gastrotrichs was found in winter (average of 33 103 indiv. m2 ), whereas the highest was found in summer (average of 1392 103 indiv. m2 ). The density differed with season and neither pH nor oxygen content had an effect upon gastrotrich densities. [ABSTRACT FROM AUTHOR]

LiDAR full-waveform provides a better description of the physical and forest vertical structure properties than discrete LiDAR since it registers the full wave that interacts with the canopy. In this paper, the effect of flight line side-lap is analysed on forest structure and canopy fuel variables estimations. Differences are related to pulse density changes between flight stripe side-lap areas, varying the point density between 2.65 m-2 and 33.77 m-2 in our study area. These differences modify metrics extracted from data and therefore variable values estimated from these metrics such as forest stand variables. In order to assess this effect, 64 pairwise samples were selected in adjacent areas with similar canopy structure, but having different point densities. Two parameters were tested and evaluated to minimise this effect: voxel size and voxel value assignation testing maximum, mean, median, mode, percentiles 90 and 95. Student's t-test or Wilcoxon test were used for the comparison of paired samples. Moreover, the absolute value of standardised paired samples was calculated to quantify dissimilarities. It was concluded that optimizing voxel size and voxel value assignation minimised the effect of point density variations and homogenised full-waveform metrics. Height/median ratio (HTMR) and Vertical distribution ratio (VDR) had the lowest variability between different densities, and Return waveform energy (RWE) reached the best improvement with respect to initial data, being the difference between standardised paired samples 1.28 before and 0.69 after modification. [ABSTRACT FROM AUTHOR]

Thermoxidative ageing of elastomers is investigated by having a closer look on the consumption and diffusion of oxygen during the exposure to elevated temperatures. After the introduction of some basic theory an experimental set-up is described, which enables the measurement of the oxygen amount being absorbed during weathering. Hence the oxygen consumption of natural rubber was detected at elevated temperatures and for varying exposure times. The correlation of changes in the mechanical properties and the oxygen consumption is analysed in order to get new awareness of oxidation affecting the mechanical behaviour. Influences of diffusion effects on the degradation are investigated by the use of micro X-ray tomography, which detects minor changes in density generated by oxidation. Density profiles over the cross-section of the samples are created, which illustrate the appearance of diffusion-limiting oxidation. The results offer a closer look at the thermoxidative ageing of natural rubber and should help to get a better understanding of the degradation during ageing. Finally the findings may improve the life-time prediction of elastomeric components by providing the basis for the development of advanced material models. [ABSTRACT FROM AUTHOR]

The article presents a study on the breeding of birds and dynamics of their community in a forest at the Białowieża National Park in Poland.

Abstract: Purpose: This study investigates the clinical radiobiology of radiation induced lung disease in terms of regional computed tomography (CT) density changes following intensity modulated radiotherapy (IMRT) for non-small-cell lung cancer (NSCLC). Methods: A total of 387 follow-up CT scans in 131 NSCLC patients receiving IMRT to a prescribed dose of 60 or 66Gy in 2Gy fractions were analyzed. The dose-dependent temporal evolution of the density change was analyzed using a two-component model, a superposition of an early, transient component and a late, persistent component. Results: The CT density of healthy lung tissue was observed to increase significantly (p <0.0001) for all dose levels after IMRT. The time evolution and the size of the density signal depend on the local delivered dose. The transient component of the density signal was found to peak in the range of 3–4months, while the density tends to stabilize at times >12months. Conclusions: The radiobiology of lung injury may be analyzed in terms of CT density change. The initial transient change in density is consistent with radiation pneumonitis, while the subsequent stabilization of the density is consistent with pulmonary fibrosis. [Copyright &y& Elsevier]

Purpose: To describe regional lung tissue density changes in normal lung tissue of patients with primary and metastatic lung tumors who received stereotactic body radiation therapy (SBRT). Methods and Materials: A total of 179 post-SBRT follow-up computed tomography (CT) scans of 62 patients who received SBRT between 2003 and 2009 were studied. Median prescription dose was 54 Gy (range, 30-60 Gy) in 3 to 5 fractions. SBRT-induced lung density changes on post-SBRT follow-up CT were evaluated at approximately 3, 6, 12, 18, 24, and 30 months after treatment. Dose-response curves (DRC) were generated for SBRT-induced lung damage by averaging CT number (HU) changes for regions of the lungs receiving the same dose at 5-Gy intervals. Results: For all follow-up interval periods, CT numbers linearly increased with dose until 35 Gy and were constant thereafter. For 3, 18, 24, and 30 months, the rate of relative electron density increase with dose was approximately 0.24% per Gy. At 6 months, the rate was also similar below 20 Gy but then rose to 0.6% per Gy above this threshold. After 6 months, DRCs were mostly time-independent. When split between patients treated with 3 fractions of 12 to 20 Gy (median, 20 Gy; average tumor volume, 12 ± 16 cm3) and with >3 fractions of 6 to 12.5 Gy (median, 9 Gy; average tumor volume, 30 ± 40 cm3), DRCs differed significantly. In both cases, CT changes at 3, 18, 24, and 30 months were identical to those of the population DRC; however, patients who received >3 fractions showed 6-month CT changes that were more than twice those for the group that received 3 fractions. Conclusions: This analysis of SBRT-induced normal lung density changes indicates that lung normal tissue has more pronounced self-limited acute effects than late effects. Differences in acute CT changes following treatments in 3 fractions were considerably less than for treatments in >3 fractions. [ABSTRACT FROM AUTHOR]

Purpose: Radiologic lung density changes are observed in more than 50% of patients after stereotactic body radiotherapy (SBRT) for lung cancer. We studied the relationship between SBRT dose and posttreatment computed tomography (CT) density changes, a surrogate for lung injury. Methods and Materials: The SBRT fractionation schemes used to treat Stage I lung cancer with RapidArc were three fractions of 18 Gy, five fractions of 11 Gy, or eight fractions of 7.5 Gy, prescribed at the 80% isodose. Follow-up CT scans performed at less than 6 months (n = 50) and between 6 and 9 months (n = 30) after SBRT were reviewed. Posttreatment scans were coregistered with baseline scans using a B-spline deformable registration algorithm. Voxel-Hounsfield unit histograms were created for doses between 0.5 and 50 Gy. Linear mixed effects models were used to assess the effects of SBRT dose on CT density, and the influence of possible confounders was tested. Results: Increased CT density was associated with higher dose, increasing planning target volume size, and increasing time after SBRT (all p < 0.0001). Density increases were apparent in areas receiving >6 Gy, were most prominent in areas receiving >20 Gy, and seemed to plateau above 40 Gy. In regions receiving >36 Gy, the reduction in air-filled fraction of lung after treatment was up to 18%. No increase in CT density was observed in the contralateral lung receiving ≥3 Gy. Conclusions: A dose–response relationship exists for quantitative CT density changes after SBRT. A threshold of effect is seen at low doses, and a plateau at highest doses. [ABSTRACT FROM AUTHOR]

The present study was undertaken to evaluate the regeneration of bone in the extraction socket by using computer- assisted densitometric image analysis (CADIA) in 10 patients with bilateral symmetrical mandibular third molar impactions, after extraction. In one side hydroxyapatite (HA) was placed into the socket and on the other side no graft was placed. Standardized intraoral periapical radiograph (IOPA) and orthopantomograph (OPG) were taken, 15 days postoperatively, and at 3 and 6 months interval. These radiographs were scanned by using CADIA and images were compared, which showed more density on the graft side. The radiographic data were compared to clinical parameters. The results indicated that CADIA may be useful in assessing the bone density changes in an extraction socket. [ABSTRACT FROM AUTHOR]

The article focuses on the impact of anthropogenic changes to bird's breeding dynamics in Bialowieza National Park between 2005-2009. In the authors' study, they focused on changes in the three forest type including ash-alder riverine, oak-hornbeam and mixed coniferous forest and they found that the increase in Sylvania atricapilla was the only change that happened in the forest. They also disclosed that 18 of 26 common species in the areas saw an increase in their numbers in 2005-2009 compared to that in 1975-2009. They conclude that the changes in the forest did not affect the change in bird numbers.

Surveys of the benthic macroinvertebrate community were conducted in the main basin of Lake Huran in 2000 and 2003, and in Georgian Bay and North Channel in 2002. Results were compared to surveys conducted in the 1960s and early 1970s. Although data of earlier surveys were inconsistent, our best estimates suggest that total density of the four major benthic taxa (Diporeia spp., Oligochaeta, Sphaeriidae, and Chironomidae) in the main basin declined dramatically between the early 1970s and 2000. Populations of all major taxa continued to decline between 2000 and 2003, particularly Diporeia and Sphaeriidae. Diporeia was rare or absent in the southern end of the lake and in some nearshore areas in 2000, and by 2003 was not found at depths < 50 m except in the far northeastern end of the lake. Densities of the major taxa in Georgian Bay and North Channel in 2002 were not different from densities in 1973 despite differences in survey methods. A limited study in southern Georgian Bay, however, found that densities of both Diporeia and Sphaeriidae declined to zero at most sites between 2000 and 2004. The population of Dreissena polymorpha was stable in all lake areas, but Dreissena bugensis increased, particularly at the 31-50 m depth interval in the main basin. Since there were no extensive surveys in Lake Huron in the period between nutrient abatement (late 1970s) and the establishment of Dreissena (early 1990s), it is difficult to determine relative roles of these events on observed declines. However, since phosphorus loads have been stable since the early 1980s, declines between 2000 and 2003 can likely be attributed to Dreissena. [ABSTRACT FROM AUTHOR]

Grey partridge Perdix perdix populations were monitored in the years 1991–2004 in ten agricultural areas (100–200 km2 each) located in various regions of Poland. Spring density (call counts in March/April) and parameters describing reproductive success (counts of adult and young birds in coveys found in August) were estimated, and annual survival rate of adult birds was calculated. In the 1990s, the mean spring density of grey partridge in Poland showed a threefold decrease. In 1993 (the year of the highest mean density), from 4.6 pairs/km2 to 20.0 pairs/km2 were found in individual areas; whereas in 2004, there were from 0.4 pairs/km2 to 8.3 pairs/km2. The mean brood-production rate in individual years ranged from 29% to 49% (overall mean 36.8%), the chick-survival rate from 31% to 56% (43.1%), the young production from 1.6 to 2.8 young per adult (2.32 young/adult) and the annual survival rate of adult birds from 25% to 33% (28.3%). The population decrease in the 1990s was connected with the drop of reproductive success, including both the brood-production rate and the chick-survival rate, as well as with the decline of annual survival rate of adult birds. The decrease of brood-production rate and adult-survival rate probably resulted mainly from increased abundance of nest and incubating female predators (particularly foxes). Fluctuations in chick-survival rate were related to weather conditions, but also slight long-term decline was recorded, probably due to more intensive pesticide use. [ABSTRACT FROM AUTHOR]

Temporal gravity changes provide information about mass and/or density variations within and below the volcano edifice. Three active volcanoes have been under investigation; each of them related to a plate boundary: Mayon/Luzon/Philippines, Merapi/Java/Indonesia, and Galeras/Colombia. The observed gravity changes are smaller than previously expected but significant. For the three volcanoes under investigation, and within the observation period, mainly the increase of gravity is observed, ranging from 1,000 nm-2 to 1,600 nms-2. Unexpectedly, the gravity increase is confined to a rather small area with radii of 5 to 8 km around the summit. At Mayon and Merapi the parallel GPS measurements yield no significant elevation changes. This is crucial for the interpretation, as the internal pressure variations do not lead to significant deformation at the surface. Thus the classical Mogi-model for a shallow extending magma reservoir cannot apply. To confine the possible models, the attraction due to changes of groundwater level or soil moisture is estimated along the slope of Merapi exemplarily by 2-D modelling. Mass redistribution or density changes were evaluated within the vent as well as deeper fluid processes to explain the gravity variations; the results are compared to the model incorporating the additional effect of elastic deformation. [ABSTRACT FROM AUTHOR]

• Relative surface area alone does not determine sinking of bio-fouled plastic. • Once it sinks, plastic in all but the deepest waters may remain negatively buoyant. • Microbes alone only cause sinking of plastic pieces with surface-area:volume ratios above 100. • Results suggest a size tipping point where invertebrates vs. microbes cause plastic to sink. Biofouling causing an increase in plastic density and sinking is one of the hypotheses to account for the unexpectedly low amount of buoyant plastic debris encountered at the ocean surface. Field surveys show that polyethylene and polypropylene, the two most abundant buoyant plastics, both occur below the surface and in sediments, and experimental studies confirm that biofouling can cause both of these plastics to sink. However, studies quantifying the actual density of fouled plastics are rare, despite the fact that density will determine the transport and eventual fate of plastic in the ocean. Here we investigated the role of microbial biofilms in sinking of polyethylene microplastic and quantified the density changes natural biofouling communities cause in the coastal waters of the North Sea. Molecular data confirmed the variety of bacteria and eukaryotes (including animals and other multicellular organisms) colonizing the plastic over time. Fouling communities increased the density of plastic and caused sinking, and the plastic remained negatively buoyant even during the winter with lower growth rates. Relative surface area alone, however, did not predict whether a plastic piece sank. Due to patchy colonization, fragmentation of sinking pieces may result in smaller pieces regaining buoyancy and returning to the surface. Our results suggest that primarily multicellular organisms cause sinking of plastic pieces with surface area to volume ratios (SA:V) below 100 (generally pieces above a couple hundred micrometers in size), and that this is a "tipping point" at which microbial biofilms become the key players causing sinking of smaller pieces with higher SA:V ratios, including most fibers that are too small for larger (multicellular) organisms to colonize. [Display omitted] [ABSTRACT FROM AUTHOR]

The measurement of density changes in solid samples of less than one gram is often of practical interest. We describe here such relative measurements having a precision of a few parts in 10 4 using a newly reported apparatus. Comparisons of results with theory are presented.