Thermal Enhancement of Cellular Radiation Damage: A Review of Complementary and Synergistic Effects

Hyperthermia treatment can kill mammalian cells in a time and temperature dependent manner. Thermal sensitivity varies extensively among various cell lines in culture and cellular molecular and ultrastructural studies have not resolved which cellular mechanisms underlie thermal cell killing and radiosensitization. The response of cells to heat and radiation are complementary under certain conditions found in human tumors, such as hypoxia, low pH, low nutrient and the S-phase of the cell cycle. Thus, hyperthermia can be used as a complementary treatment modality in the radiotherapy of human cancer. Further studies show that heat treatment causes radiosensitization which is in part associated with the inhibition of repair of radiation damage and is strongly dependent on temperature and on the sequencing. In addition, the conditions such as pH and oxygenation during treatment sequencing can influence the degree of recovery of cells. These factors may be exploited in optimizing therapeutic gain in clinical cancer therapy. Data are shown that transformation from the normal to the tumorigenic state causes random small changes in radiosensitivity and heat sensitivity. Also, treatments combining heat and radiation can lead to increased or decreased transformation in cells depending on the treatment sequence

A Test of Independence in Two-Way Contingency Tables Based on Maximal Correlation

Cataloged from PDF version of article.Maximal correlation has several desirable properties as a measure of dependence, including the fact that it vanishes if and only if the variables are independent. Except for a few special cases, it is hard to evaluate maximal correlation explicitly. We focus on two-dimensional contingency tables and discuss a procedure for estimating maximal correlation, which we use for constructing a test of independence. We compare the maximal correlation test with other tests of independence by Monte Carlo simulations. When the underlying continuous variables are dependent but uncorrelated, we point out some cases for which the new test is more powerful

The Effect of Colcemid on the Heat Survival of Mitotic V79 Chinese Hamster Cells

V79 Chinese hamster cells were collected by colcemid addition to study the effect of heat on mitosis. When they were heated at 42°C and 45°C in the presence of 0.06 μg/mL colcemid, cell survival increased over the control samples, which were heated in ordinary medium. Scanning electron microscopy showed that cells heated to 45°C in the presence or absence of colcemid had fewer microvilli on the surface, but they did not have increased bleb formation. Transmission electron microscopy showed that the chromatin was diffuse in the heated cells and the kinetochores were indistinct. The mitochondria in the heated cells were also swollen and contained visible particles

Activity of 50 Long-Period Comets Beyond 5.2 AU

Remote investigations of the ancient solar system matter has been traditionally carried out through the observations of long-period (LP) comets that are less affected by solar irradiation than the short-period counterparts orbiting much closer to the Sun. Here we summarize the results of our decade-long survey of the distant activity of LP comets. We found that the most important separation in the dataset is based on the dynamical nature of the objects. Dynamically new comets are characterized by a higher level of activity on average: the most active new comets in our sample can be characterized by afrho values >3--4 higher than that of our most active returning comets. New comets develop more symmetric comae, suggesting a generally isotropic outflow. Contrary to this, the coma of recurrent comets can be less symmetrical, ocassionally exhibiting negative slope parameters, suggesting sudden variations in matter production. The morphological appearance of the observed comets is rather diverse. A surprisingly large fraction of the comets have long, teniouos tails, but the presence of impressive tails does not show a clear correlation with the brightness of the comets.Comment: 21 pages, 4 figures, accepted for publication in A

Scanning Electron Microscope Observations of Growth and Ochratoxin - A Production of Aspergillus alutaceus Variety alutaceus (Formerly A. ochraceus) on Gamma-Irradiated Barley

Scanning electron microscope examination, colony counting and biochemical studies were conducted to describe the effect of gammairradiation on growth and ochratoxin A production by Aspergillus alutaceus. Irradiation at a dose of 1.0 or 2.0 kGy reduced the level of mold growth greatly relative to unirradiated controls. Growth in the irradiated samples after 7 to 12 day incubation was mainly in cracks in the hull, and less mycelium was seen on the grain surface. In unirradiated controls, mycelial growth was heavy and, although conidial heads were most abundant in cracks in the hull, they were seen over the whole surface. Vhen the barley was inoculated before irradiation, the number of colony forming units (cfu) at 5 days after 1.0 or 2.0 kGy irradiation was lower than in the unirradiated controls; however, the number increased over the control by 30 days. A dose of 4.0 kGy eliminated viable fungi. Ochratoxin A production decreased from the control level of 17.6 μg/g with increased dose and was below the detection limit above 4.0 kGy. Vhen barley was inoculated after irradiation the spore count and the ochratoxin A level were higher than the unirradiated control after 27 days. We conclude that the difference in growth and ochratoxin A production on irradiated and unirradiated barley is due to the effect of irradiation on the natural competitive microflora on the grain surface and the reduction of inoculum size of the A. alutaceus by radiation

The Szemeredi-Trotter Theorem in the Complex Plane

It is shown that $n$ points and $e$ lines in the complex Euclidean plane ${\mathbb C}^2$ determine $O(n^{2/3}e^{2/3}+n+e)$ point-line incidences. This bound is the best possible, and it generalizes the celebrated theorem by Szemer\'edi and Trotter about point-line incidences in the real Euclidean plane ${\mathbb R}^2$.Comment: 24 pages, 5 figures, to appear in Combinatoric

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to dominate flow behavior, in some cases producing double circulation loops in the weld pool

ABSTRACT. A mathematical model has been developed to account for convection and temperature distributions in stationary arc weld pools driven by buoyancy, electromagnetic and surface tension forces. It is shown that the electromagnetic and surface tension forces dominate the flow behavior. In some cases, these forces produce double circulation loops, which are indirectly confirmed by experimental measurements of segregation in the weld pool. It is also shown that the surface tension driven flows are very effective in dissipating the incident energy flux on the pool surface which, in turn, reduces the vaporization from the weld pool

The 21-item Barratt Impulsiveness Scale Revised (BIS-R-21): an alternative three-factor model

Background and aims: Due to its important role in both healthy groups and those with physical, mental and behavioral disorders, impulsivity is a widely researched construct. Among various self-report questionnaires of impulsivity, the Barratt Impulsiveness Scale is arguably the most frequently used measure. Despite its international use, inconsistencies in the suggested factor structure of its latest version, the BIS-11, have been observed repeatedly in different samples. The goal of the present study was therefore to test the factor structure of the BIS-11 in several samples. Methods: Exploratory and confirmatory factor analyses were conducted on two representative samples of Hungarian adults (N 5 2,457; N 5 2,040) and a college sample (N 5 765). Results: Analyses did not confirm the original model of the measure in any of the samples. Based on explorative factor analyses, an alternative three-factor model (cognitive impulsivity; behavioral impulsivity; and impatience/ restlessness) of the Barratt Impulsiveness Scale is suggested. The pattern of the associations between the three factors and aggression, exercise, smoking, alcohol use, and psychological distress supports the construct validity of this new model. Discussion: The new measurement model of impulsivity was confirmed in two independent samples. However, it requires further cross-cultural validation to clarify the content of self-reported impulsivity in both clinical and nonclinical samples

SN 2016coi/ASASSN-16fp: An example of residual helium in a type Ic supernova?

The optical observations of Ic-4 supernova (SN) 2016coi/ASASSN-16fp, from $\sim 2$ to $\sim450$ days after explosion, are presented along with analysis of its physical properties. The SN shows the broad lines associated with SNe Ic-3/4 but with a key difference. The early spectra display a strong absorption feature at $\sim 5400$ \AA\ which is not seen in other SNe~Ic-3/4 at this epoch. This feature has been attributed to He I in the literature. Spectral modelling of the SN in the early photospheric phase suggests the presence of residual He in a C/O dominated shell. However, the behaviour of the He I lines are unusual when compared with He-rich SNe, showing relatively low velocities and weakening rather than strengthening over time. The SN is found to rise to peak $\sim 16$ d after core-collapse reaching a bolometric luminosity of Lp $\sim 3\times10^{42}$ \ergs. Spectral models, including the nebular epoch, show that the SN ejected $2.5-4$ \msun\ of material, with $\sim 1.5$ \msun\ below 5000 \kms, and with a kinetic energy of $(4.5-7)\times10^{51}$ erg. The explosion synthesised $\sim 0.14$ \msun\ of 56Ni. There are significant uncertainties in E(B-V)host and the distance however, which will affect Lp and MNi. SN 2016coi exploded in a host similar to the Large Magellanic Cloud (LMC) and away from star-forming regions. The properties of the SN and the host-galaxy suggest that the progenitor had $M_\mathrm{ZAMS}$ of $23-28$ \msun\ and was stripped almost entirely down to its C/O core at explosion.Comment: Accepted for publication in MNRAS. Updated to reflect the published version, minor typographical changes onl

Do Europe's borders need multi-faceted biometric protection

In today’s world, terrorism has become a dire and global threat. Within Europe, terror attacks and participation in terrorist organisations by EU citizens are on the rise. To deal with this, the European Union has introduced some significant legal changes to the Schengen agreement – the treaty that led to the creation of Europe’s Schengen area where internal border checks have largely been abolished. The most recent and interesting of these changes has meant that systematic controls are being introduced at border crossings