Gypsy moths and American dog ticks: Space partners

An experiment intended for the space shuttle and designed to investigate the effects of weightlessness and total darkness on gypsy moth eggs and engorged American dog ticks is described. The objectives are: (1) to reevaluate the effects of zero gravity on the termination of diapause/hibernation of embryonated gypsy moth eggs, (2) to determine the effect of zero gravity on the ovipositions and subsequent hatch from engorged female American dog ticks that have been induced to diapause in the laboratory, and (3) to determine whether morphological or biochemical changes occur in the insects under examination. Results will be compared with those from a similar experiment conducted on Skylab 4

Reduction Operators of Linear Second-Order Parabolic Equations

The reduction operators, i.e., the operators of nonclassical (conditional) symmetry, of (1+1)-dimensional second order linear parabolic partial differential equations and all the possible reductions of these equations to ordinary differential ones are exhaustively described. This problem proves to be equivalent, in some sense, to solving the initial equations. The ``no-go'' result is extended to the investigation of point transformations (admissible transformations, equivalence transformations, Lie symmetries) and Lie reductions of the determining equations for the nonclassical symmetries. Transformations linearizing the determining equations are obtained in the general case and under different additional constraints. A nontrivial example illustrating applications of reduction operators to finding exact solutions of equations from the class under consideration is presented. An observed connection between reduction operators and Darboux transformations is discussed.Comment: 31 pages, minor misprints are correcte

Policy options for including LULUCF in the EU reduction commitment and policy instruments for increasing GHG mitigation efforts in the LULUCF and agriculture sectors

Land use, land-use change and forestry (LULUCF) is an inventory sector defined by the Intergovern-mental Panel on Climate Change (IPCC) that covers anthropogenic emissions and removals of GHGs resulting from changes in terrestrial carbon stocks. The EU has committed unilaterally to reduce its overall greenhouse gas (GHG) emissions to 20 % be-low 1990 levels by 2020, and to 30 % below 1990 levels if conditions are right

Identification of a nearby stellar association in the Hipparcos catalog: implications for recent, local star formation

The TW Hydrae Association (~55 pc from Earth) is the nearest known region of recent star formation. Based primarily on the Hipparcos catalog, we have now identified a group of 9 or 10 co-moving star systems at a common distance (~45 pc) from Earth that appear to comprise another, somewhat older, association (``the Tucanae Association''). Together with ages and motions recently determined for some nearby field stars, the existence of the Tucanae and TW Hydrae Associations suggests that the Sun is now close to a region that was the site of substantial star formation only 10-40 million years ago. The TW Hydrae Association represents a final chapter in the local star formation history.Comment: 5 pages incl figs and table

L-arginase induces vascular dysfunction in old spontaneously hypertensive rats

Background: Aging is a major non-modifiable risk factor for hypertension. Changes in aging are similar to those seen in hypertension in the vasculature. Also, aging increases the vascular dysfunction that occurs in hypertension. L-arginase action reduces substrate (L-arginine) availability for the formation of nitric oxide (NO). This reduces the level of NO and leads to reduced vasodilation and ultimately, vascular dysfunction. This study examines the hypothesis that age-dependent vascular dysfunction in SHRs is mediated by arginase.Methods: Young (12-14 weeks) and old (11-12 months) male Wistar and spontaneously hypertensive rats (SHR) were used. Mean arterial pressure (MAP) was measured in the rats. They were then euthanized and mesenteric resistance arteries (MRAs) and thoracic aortae were excised and placed in ice-cold physiological salt solution (PSS). Arterial segments were either snap-frozen in liquid nitrogen and stored for immunoblotting studies or cut into 2mm rings for reactivity studies. Cumulative concentration-response curves to acetylcholine (Ach; 10-9 – 3x10-5M) and sodium nitroprusside (SNP; 10-12 – 3x10-5 M) were performed in the absence or presence (30-minute exposure) of L-arginase, 0.05U/ML (MRA) or 0.5U/ML (aorta). Vessels were pre-contracted with phenylephrine (PE; 3x10-6M)Results: MAP increased during aging in the SHRs p<0.05 but not in the Wistar rats. Arginase impaired the endothelium-dependent relaxation responses of thoracic aortic and MRA arterial rings to Ach in the old Wistars and SHRs (Emax aorta: 29.42±2.19% vs 7.94±1.86%). Arginase also impaired endothelium-independent relaxation response to SNP in the old SHRs only (Emax aorta: 88.62±4.10% vs 31.45±10.61%). We also observed no differences in the serum arginase activity in the four groups of rats. On the contrary, arginase activity in the aortae of young Wistar rats was reduced compared to other groups.Conclusions: Arginase impairs both endothelium-dependent and –independent vasorelaxation responses, through the NO signaling pathway.Keywords: Hypertension, Arginase, aging, vascular dysfunction, endothelium, Nitric oxid

Microstructure identification via detrended fluctuation analysis of ultrasound signals

We describe an algorithm for simulating ultrasound propagation in random one-dimensional media, mimicking different microstructures by choosing physical properties such as domain sizes and mass densities from probability distributions. By combining a detrended fluctuation analysis (DFA) of the simulated ultrasound signals with tools from the pattern-recognition literature, we build a Gaussian classifier which is able to associate each ultrasound signal with its corresponding microstructure with a very high success rate. Furthermore, we also show that DFA data can be used to train a multilayer perceptron which estimates numerical values of physical properties associated with distinct microstructures.Comment: Submitted to Phys. Rev.

The Broadband Spectrum of Galaxy Clusters

We examine whether nonthermal protons energized during a cluster merger are simultaneously responsible for the Coma cluster's diffuse radio flux (via secondary decay) and the departure of its intra-cluster medium (ICM) from a thermal profile via Coulomb collisions between the quasithermal electrons and the hadrons. Rather than approximating the influence of nonthermal proton/thermal electron collisions as extremely rare events which cause an injection of nonthermal, power-law electrons (the `knock-on' approximation), we self-consistently solve (to our knowledge, for the first time) the covariant kinetic equations for the two populations. The electron population resulting from these collisions is out of equilibrium, yet not a power law, and importantly displays a higher bremsstrahlung radiative efficiency than a pure power law. Observations with GLAST will test this model directly.Comment: Accepted for publication in Ap

Orbital motion of the young brown dwarf companion TWA 5 B

With more adaptive optics images available, we aim at detecting orbital motion for the first time in the system TWA 5 A+B. We measured separation and position angle between TWA 5 A and B in each high-resolution image available and followed their change in time, because B should orbit around A. The astrometric measurement precision is about one milli arc sec. With ten year difference in epoch, we can clearly detect orbital motion of B around A, a decrease in separation by ~ 0.0054 arc sec per year and a decrease in position angle by ~ 0.26 degrees per year. TWA 5 B is a brown dwarf with ~ 25 Jupiter masses (Neuh\"auser et al. 2000), but having large error bars (4 to 145 Jupiter masses, Neuh\"auser et al. 2009). Given its large projected separation from the primary star, ~ 86 AU, and its young age ~ 10 Myrs), it has probably formed star-like, and would then be a brown dwarf companion. Given the relatively large changes in separation and position angle between TWA 5 A and B, we can conclude that they orbit around each other on an eccentric orbit. Some evidence is found for a curvature in the orbital motion of B around A - most consistent with an elliptic (e=0.45) orbit. Residuals around the best-fit ellipse are detected and show a small-amplitude (~ 18 mas) periodic sinusoid with ~ 5.7 yr period, i.e., fully consistent with the orbit of the inner close pair TWA 5 Aa+b. Measuring these residuals caused by the photocenter wobble - even in unresolved images - can yield the total mass of the inner pair, so can test theoretical pre-main sequence models.Comment: 6 pages, 4 figures, accepted for publication in A&A; corrected typo in amplitude below Fig.

Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006

A joint spectral analysis of some Chandra ACIS X-ray data and Molonglo Observatory Synthesis Telescope radio data was performed for 13 small regions along the bright northeastern rim of the supernova remnant SN 1006. These data were fitted with a synchrotron radiation model. The nonthermal electron spectrum used to compute the photon emission spectra is the traditional exponentially cut off power law, with one notable difference: The power-law index is not a constant. It is a linear function of the logarithm of the momentum. This functional form enables us to show, for the first time, that the synchrotron spectrum of SN 1006 seems to flatten with increasing energy. The effective power-law index of the electron spectrum is 2.2 at 1 GeV (i.e., radio synchrotron-emitting momenta) and 2.0 at about 10 TeV (i.e., X-ray synchrotron-emitting momenta). This amount of change in the index is qualitatively consistent with theoretical models of the amount of curvature in the proton spectrum of the remnant. The evidence of spectral curvature implies that cosmic rays are dynamically important instead of being "test" particles. The spectral analysis also provides a means of determining the critical frequency of the synchrotron spectrum associated with the highest-energy electrons. The critical frequency seems to vary along the northeastern rim, with a maximum value of 1.1e17 (0.6e17 - 2.1e17) Hz. This value implies that the electron diffusion coefficient can be no larger than a factor of ~4.5-21 times the Bohm diffusion coefficient if the velocity of the forward shock is in the range 2300-5000 km/s. Since the coefficient is close to the Bohm limit, electrons are accelerated nearly as fast as possible in the regions where the critical frequency is about 1.0e17 Hz.Comment: 41 pages, 8 figures, accepted by Ap