Phantom for Evaluating Accuracy of Image Registration Software

Provided is a phantom for evaluating the accuracy of image registration software based on a result of matching tomograms of a predetermined position of the phantom, taken using two or more imaging apparatuses. Accordingly, it is possible to more efficiently evaluate the accuracy of the image registration software by comparing the tomograms with one another using a three-dimensional analysis. In addition, it is possible to facilitate the comparison of the tomograms with one another by installing a plurality of indicating bars in the phantom so that their cross sections can appear on each of the tomograms

Effects of impurity molecules on the lifetime of antiprotonic helium atoms

Abstract Quenching of metastable antiprotonic helium atoms in collisions with hydrogen and deuterium molecules has been studied using laser spectroscopy at CERNÕs antiproton decelerator. The temperature dependence of the quenching cross sections of the antiprotonic states ðn; lÞ ¼ ð37; 34Þ, ð38; 35Þ and ð38; 37Þ has been investigated and a deviation from the Arrhenius law was found at low temperatures. In case of the state ð38; 37Þ with deuterium, detailed measurements revealed that the quenching cross section levels off at low temperatures indicating a strong quantum tunneling effect. Ó 2003 Elsevier B.V. All rights reserved. PACS: 36.10.)k; 34.20.Gj; 82.20.Xr Keywords: Quantum tunneling; Antiprotonic helium; Hydrogen; Deuterium; Temperature dependence of quenching cross section An antiprotonic helium atom is an exotic three-body system consisting of an antiproton, an electron and a helium nucleus ( p pHe þ p p À e À À He 2þ ). Various properties of these atoms (transition energies, state lifetimes etc.) have been extensively studied in the past years using a laser spectroscopy method According to the theoretical calculations of Sauge and Valiron, an ðn; lÞ-dependent activation barrier exists for this kind of reaction which could explain the observed quenching behaviour where r 0 is the cross section at infinitely high temperatures (this we expect to be close to the geometrical cross section), E b is the height of the activation barrier, k is the Boltzmann constant and T is the temperature. However, all previous measurements of quenching by hydrogen and deuterium molecules were done at 30 K; therefore in 2002 we measured the quenching cross sections of three metastable antiprotonic states at higher temperatures to test the above temperature dependence and possibly determine the reaction barrier heights. These measurements, together with the theoretical calculations, can give us a better understanding of the physico-chemistry of cold interstellar and protostellar clouds where similar low temperature reactions play a significant role, especially various hydrogen/deuterium fractionation processes that cause enrichment of deuterium in these environments. The quenching cross section of a metastable antiprotonic state can be obtained by measuring the decay rate of the state at different impurity concentrations using laser spectroscopy. Assuming that the antiprotonic helium atoms are quenched in binary collisions with the impurity molecules, the decay rate cðn; lÞ of the state then can be expressed as cðn; lÞ ¼ c 0 ðn; lÞ þ n imp v th r q ðn; lÞ; ð2Þ where c 0 ðn; lÞ is the ÔintrinsicÕ decay rate of the state in pure helium which can be calculated theoretically, n imp is the number density of the impurity molecules, is the relative velocity of the colliding molecules The decay rate of a metastable state can be measured using two methods which are based on the same laser spectroscopy method. Antiprotonic states can be either long-lived metastable states from where antiprotons can de-excite to lowerlying states by emitting a photon, or short-lived states from where antiprotons annihilate on the helium nucleus. Due to this difference in the lifetime, short-lived states have very small antiproton population compared to long-lived states. Antiprotons in a long-lived metastable state can be efficiently stimulated by a laser pulse to make a transition to a short-lived state if we choose a transition that satisfies the rules Dn ¼ AE1 and Dl ¼ AE1. Under such conditions, a laser pulse tuned to a metastable-to-short-lived transition and fired into the target containing p pHe þ atoms will produce a peak in the annihilation time spectrum of the antiprotons, since it suddenly increases the population of the short-lived state. If the state whose quenching cross section we want to measure can be the parent state of such a metastable-toshort-lived laser-induced transition, then the decay rate c of the state can be obtained in the following way. We measure the area of the laser-induced peak in the antiproton annihilation time spectrum (normalized to the total background) at different laser firing times. Since the area of the peak is proportional to the population of the parent state at the time of the laser firing, this way we obtain the population lifetime s p of the parent state. If feeding to this state from upper states is negligible, then the inverse of this lifetime is equal to the decay rate of the state: c ¼ 1=s p . This is the Ôt1-scanÕ method If the state is not accessible with an ordinary laser-induced transition described above, the hydrogen-assisted inverse resonance (HAIR) or deuterium-assisted inverse resonance (DAIR) methods can be used Our gas target consisted of 4 He to which hydrogen or deuterium was premixed at molar concentrations of 30-10,000 ppm. We used a cryogenic target chamber for the measurements between 25 and 100 K, and another target chamber with a larger target volume for the room temperature measurements. Both chambers have a stainless steel window on the upstream wall for the antiproton beam, and a quartz window on the downstream wall for the laser beam. The temperature of the cryogenic target was measured with a silicon diode sensor with an uncertainty of 1 K. The temperature of the room temperature target was not measured directly so an uncertainty of 2 K was assigned in these cases. The absolute number density of the H 2 and D 2 molecules was varied not only by changing gas mixture but also by changing the pressure of the gas target between 1 and 8 bar. Although increasing pressure decreases the lifetime of metastable states, this effect is negligible compared to the lifetime shortening caused by the increasing density of the H 2 and D 2 molecules We determined the decay rates of the following metastable antiprotonic states: ðn; lÞ ¼ ð37; 34Þ with hydrogen and deuterium using the transition ð37; 34Þ ! ð36; 33Þ with the t1-scan method, ð38; 35Þ with hydrogen and deuterium using the transition ð37; 34Þ ! ð38; 35Þ with the HAIR/ DAIR method, and ð38; 37Þ with hydrogen and deuterium using the transition ð37; 36Þ ! ð38; 37Þ with the HAIR/DAIR method. If the decay rates measured at a given temperature and for a given antiprotonic state and the theoretically calculated decay rate in pure helium (i.e. at n imp ¼ 0) where r t is independent of the temperature. The term r t in Eq. (3) is most likely related to the quantum tunneling of the colliding molecule through the activation barrier, as suggested by Sauge and Valiron The geometrical cross section of the D 2 -He collision is 21 · 10 À16 cm

AMPK Is Essential to Balance Glycolysis and Mitochondrial Metabolism to Control T-ALL Cell Stress and Survival

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy associated with Notch pathway mutations. While both normal activated and leukemic T cells can utilize aerobic glycolysis to support proliferation, it is unclear to what extent these cell populations are metabolically similar and if differences reveal T-ALL vulnerabilities. Here we show that aerobic glycolysis is surprisingly less active in T-ALL cells than proliferating normal T cells and that T-ALL cells are metabolically distinct. Oncogenic Notch promoted glycolysis but also induced metabolic stress that activated 5' AMP-activated kinase (AMPK). Unlike stimulated T cells, AMPK actively restrained aerobic glycolysis in T-ALL cells through inhibition of mTORC1 while promoting oxidative metabolism and mitochondrial Complex I activity. Importantly, AMPK deficiency or inhibition of Complex I led to T-ALL cell death and reduced disease burden. Thus, AMPK simultaneously inhibits anabolic growth signaling and is essential to promote mitochondrial pathways that mitigate metabolic stress and apoptosis in T-ALL

Terrestrial laser scanning for plot-scale forest measurement

Plot-scale measurements have been the foundation for forest surveys and reporting for over 200 years. Through recent integration with airborne and satellite remote sensing, manual measurements of vegetation structure at the plot scale are now the basis for landscape, continental and international mapping of our forest resources. The use of terrestrial laser scanning (TLS) for plot-scale measurement was first demonstrated over a decade ago, with the intimation that these instruments could replace manual measurement methods. This has not yet been the case, despite the unparalleled structural information that TLS can capture. For TLS to reach its full potential, these instruments cannot be viewed as a logical progression of existing plot-based measurement. TLS must be viewed as a disruptive technology that requires a rethink of vegetation surveys and their application across a wide range of disciplines. We review the development of TLS as a plotscale measurement tool, including the evolution of both instrument hardware and key data processing methodologies. We highlight two broad data modelling approaches of gap probability and geometrical modelling and the basic theory that underpins these. Finally, we discuss the future prospects for increasing the utilisation of TLS for plot-scale forest assessment and forest monitoring

Public perceptions of mangrove forests matter for their conservation

Abstract not available

Griffiths Phases on Complex Networks

Quenched disorder is known to play a relevant role in dynamical processes and phase transitions. Its effects on the dynamics of complex networks have hardly been studied. Aimed at filling this gap, we analyze the contact process, i.e., the simplest propagation model, with quenched disorder on complex networks. We find Griffiths phases and other rare-region effects, leading rather generically to anomalously slow (algebraic, logarithmic, ?) relaxation, on Erdős-R?nyi networks. Similar effects are predicted to exist for other topologies with a finite percolation threshold. More surprisingly, we find that Griffiths phases can also emerge in the absence of quenched disorder, as a consequence of topological heterogeneity in networks with finite topological dimension. These results have a broad spectrum of implications for propagation phenomena and other dynamical processes on networks

Density effects on the blocking of ions guided through insulating PET capillaries

Guiding of 3 keV Ne7 through untilted nanocapillaries in polyethylene terephthalate PET has been measured. The fraction of the transmitted ions is found to decrease with increasing charge insertion into the capillaries. This blocking effect is shown to be strongly dependent on the capillary densit