Packing Squares in a Torus

The densest packings of N unit squares in a torus are studied using analytical methods as well as simulated annealing. A rich array of dense packing solutions are found: density-one packings when N is the sum of two square integers; a family of "gapped bricklayer" Bravais lattice solutions with density N/(N+1); and some surprising non-Bravais lattice configurations, including lattices of holes as well as a configuration for N=23 in which not all squares share the same orientation. The entropy of some of these configurations and the frequency and orientation of density-one solutions as N goes to infinity are discussed.Comment: 14 pages, 9 figures; v2 reflects minor changes in published versio

Do prophylactic antipyretics reduce vaccination-associated symptoms in children?

Q: Do prophylactic antipyretics reduce vaccination-associated symptoms in children? Yes for acetaminophen, not so much for ibuprofen. Prophylactic acetaminophen reduces the odds of febrile reactions in the first 48 hours after vaccination by 40% to 65% and pain of all grades by 36% to 43%. In contrast, prophylactic ibuprofen reduces pain of all grades by 34% only after primary vaccination and doesn't alter pain after boosters. Nor does it alter early febrile reactions (strength of recommendation [SOR]: B, meta-analysis of randomized clinical trials [RCTs] with moderate-to-high risk of bias). Prophylactic administration of acetaminophen or ibuprofen is associated with a reduction in antibody response to the primary vaccine series and to influenza vaccine, but antibody responses still achieve seroprotective levels (SOR: C, bench research).Hang Chau-Glendinning, DO; Blair Baber, PharmD; Jon O. Neher, MD (Valley Family Medicine Residency, University of Washington at Valley Medical Center, Renton); Sarah Safranek, MLIS (University of Washington Health Sciences Library, Seattle)Includes bibliographical reference

Testing the Potential of Using Fungi to Convert Human Waste into Protein

We report on the results of a pilot experiment designed to test the potential of filamentous fungi (mold) to reduce solid waste (feces) while converting it into a consumable, high protein food product. Feces represent an untapped resource. Filamentous fungi are natural decomposers with the ability to use this resource. Many filamentous fungi are safe to eat. We examined growth in order to determine the conditions which maximized the rate of conversion of solid waste into fungal biomass. For this pilot, we compared the effect of different lengths of incubation, different methods of aeration, and different available surface area. The initial study resulted in rates of conversion as high as 75% (3.75g of mold produced from 5g of solid waste). Fungal growth also appeared to reduce odor. Although initially proposed as a mechanism to deal with waste and food storage issues on long-term space missions, this project holds the potential to benefit waste processing in diverse situations including large livestock confinement operations and sewage treatment facilities. This work was supported by a grant from the Indiana Space Grant Consortium (INSGC)

Hubble Space Telescope Observations of Oxygen-rich Supernova Remnants in the Magellanic Clouds. III. WFPC2 Imaging of the Young, Crab-like Supernova Remnant SNRO540-69.3

Hubble Space Telescope images with the Wide Field Planetary Camera 2 of the young, oxygen-rich, Crab-like supernova remnant SNR0540-69.3 in the Large Magellanic Cloud (LMC) reveal details of the emission distribution and the relationship between the expanding ejecta and synchrotron nebula. The emission distributions appear very similar to those seen in the Crab nebula, with the ejecta located in a thin envelope surrounding the synchrotron nebula. The [O III] emission is more extended than other tracers, forming a faint "skin" around the denser filaments and synchrotron nebula, as also observed in the Crab. The [O III] exhibits somewhat different kinematic structure in long-slit spectra, including a more extended high-velocity emission halo not seen in images. Yet even the fastest expansion speeds in SNR 0540 s halo are slow when compared to most other young supernova remnants, though the Crab nebula has similar slow expansion speeds. We show a striking correspondence between the morphology of the synchrotron nebula observed in an optical continuum filter with that recently resolved in Chandra X-ray images. We argue that the multi-component kinematics and filamentary morphology of the optical emission-line features likely result from magnetic Rayleigh-Taylor instabilities that form as the synchrotron nebula expands and sweeps up ejecta, as seen in the Crab nebula. Our images and spectra help to refine our understanding of SNR 0540 in several more detailed respects: they confirm the identification of H(alpha)+[N II] in the red spectrum, they show that the systemic velocity of SNR 0540 is not significantly different from that of the LMC, and they hint at a lower Ne abundance than the Crab (potentially indicating a more massive progenitor star)

Optical Structure and Proper-Motion Age of the Oxygen-rich Supernova Remnant 1E 0102-7219 in the Small Magellanic Cloud

We present new optical emission-line images of the young SNR 1E 0102-7219 (E0102) in the SMC obtained with the HST Advanced Camera for Surveys (ACS). E0102 is a member of the oxygen-rich class of SNRs showing strong oxygen, neon , and other metal-line emissions in its optical and X-ray spectra, and an absence of H and He. The progenitor of E0102 may have been a Wolf-Rayet star that underwent considerable mass loss prior to exploding as a Type Ib/c or IIL/b SN. The ejecta in this SNR are fast-moving (V > 1000 km/s) and emit as they are compressed and heated in the reverse shock. In 2003, we obtained optical [O III], H-alpha, and continuum images with the ACS Wide Field Camera. The [O III] image captures the full velocity range of the ejecta, and shows considerable high-velocity emission projected in the middle of the SNR that was Doppler-shifted out of the narrow F502N bandpass of a previous Wide Field and Planetary Camera 2 image from 1995. Using these two epochs separated by ~8.5 years, we measure the transverse expansion of the ejecta around the outer rim in this SNR for the first time at visible wavelengths. From proper-motion measurements of 12 ejecta filaments, we estimate a mean expansion velocity for the bright ejecta of ~2000 km/s and an inferred kinematic age for the SNR of \~2050 +/- 600 years. The age we derive from HST data is about twice that inferred by Hughes et al.(2000) from X-ray data, though our 1-sigma error bars overlap. Our proper-motion age is consistent with an independent optical kinematic age derived by Eriksen et al.(2003) using spatially resolved [O III] radial-velocity data. We derive an expansion center that lies very close to X-ray and radio hotspots, which could indicate the presence of a compact remnant (neutron star or black hole).Comment: 28 pages, 8 figures. Accepted to the Astrophysical Journal, to appear in 20 April 2006 issue. Full resolution figures are posted at: http://stevenf.asu.edu/figure

Craniofacial impalement injury: Projectile fragment to the head

Circular saws and angle grinders are two of the most dangerous pieces of electrical equipment on a worksite. Besides the danger that any high-powered, sharp piece of equipment possesses, these pieces use circular saw blades that can splinter into projectile fragments. A 60-year-old male was cutting a steel pipe with a circular saw when a fragment of the 12-inch blade flew off, impaling him in the upper face just to the right of the midline. He was wearing eyeglasses, the bridge of which was driven into his skull on impact of the fragment. He was brought to the trauma center where he underwent imaging of his face and head. This revealed that the blade and his glasses had penetrated 1.2 cm into the right frontal lobe of the brain, resulting in facial fractures and intraparenchymal hemorrhage. He underwent bifrontal craniotomy, removal of the blade and his glasses, evacuation of hematoma, and dural reconstruction. Postoperatively, he was awake with a Glasgow Coma Scale of 15 and no neurologic deficits. The complex nature of craniofacial injuries makes a multidisciplinary approach to these patients essential. Prompt diagnosis and treatment by the appropriate specialists are vital to optimize patient outcomes

DNA damage signalling from the placenta to foetal blood as a potential mechanism for childhood leukaemia initiation

Abstract For many diseases with a foetal origin, the cause for the disease initiation remains unknown. Common childhood acute leukaemia is thought to be caused by two hits, the first in utero and the second in childhood in response to infection. The mechanism for the initial DNA damaging event are unknown. Here we have used in vitro, ex vivo and in vivo models to show that a placental barrier will respond to agents that are suspected of initiating childhood leukaemia by releasing factors that cause DNA damage in cord blood and bone marrow cells, including stem cells. We show that DNA damage caused by in utero exposure can reappear postnatally after an immune challenge. Furthermore, both foetal and postnatal DNA damage are prevented by prenatal exposure of the placenta to a mitochondrially-targeted antioxidant. We conclude that the placenta might contribute to the first hit towards leukaemia initiation by bystander-like signalling to foetal haematopoietic cells

FUV and X-ray Observations of the Reverse Shock in the SMC SNR 1E 0102.2-7219

We present FUSE and XMM-Newton data for the reverse shock of the O-rich SNR 1E0102.2-7219 in the SMC. The FUSE observations cover three regions with significantly different optical [O III] intensities, all associated with the relatively bright part of the X-ray ring. Emission lines of O VI 1032, 1038 are clearly detected in the FUSE spectra. By combining this O VI doublet emission with the O VII triplet and O VIII Lyalpha fluxes from the XMM-Newton spectra and assuming a non-equilibrium ionization model with a single ionization timescale for the spectra, we are able to find a narrow range of temperatures and ionization timescales that are consistent with the respective line ratios. However, if we assume a plane-parallel shock model with a distribution of ionization timescales, the O VI emission appears to be inconsistent with O VII and O VIII in X-rays. We also analyze the total XMM-Newton EPIC-MOS 1/2 spectra for the three regions. The X-ray spectra are dominated by strong emission lines of O, Ne, and Mg, however, we detect an emission component that accounts for 14 - 25% of the flux and can be attributed to shocked ISM. We find that there is no consistent set of values for the temperature and ionization timescale which can explain the observed line ratios for O, Ne, and Mg. This would be consistent with a structured distribution of the ejecta as the O, Ne, Mg would have interacted with the reverse shock at different times.Comment: 28 pages, 5 figues, Fig. 1 as JPEG. To be published in ApJ (01 May 2006, v. 642, 1 issue