Towards Laser Driven Hadron Cancer Radiotherapy: A Review of Progress

It has been known for about sixty years that proton and heavy ion therapy is a very powerful radiation procedure for treating tumours. It has an innate ability to irradiate tumours with greater doses and spatial selectivity compared with electron and photon therapy and hence is a tissue sparing procedure. For more than twenty years powerful lasers have generated high energy beams of protons and heavy ions and hence it has been frequently speculated that lasers could be used as an alternative to RF accelerators to produce the particle beams necessary for cancer therapy. The present paper reviews the progress made towards laser driven hadron cancer therapy and what has still to be accomplished to realise its inherent enormous potential.Comment: 40 pages, 24 figure

Survival of \u3ci\u3eEscherichia coli\u3c/i\u3e 0157:H7 Added to Grass at Ensiling and Its Influence on Silage Fermentation

Escherichia coli can cause health problems in humans and livestock. It is frequently found in faeces and soil, both of which can contaminate grass harvested for silage-making. To determine the survival of E. coli 0157:H7 during ensilage, and its influence on ensilage, unwilted precision-chop grass was ensiled in laboratory silos with the following additive treatments: (a) no additive, (b) E. coli 0157:H7 (Ec - non-infectious strain, at log10 4.5 colony forming units (cfu) g-1), formic acid (FA), and (d) Ec + FA. Silos were stored at 15oC. Three silos per treatment were opened on days 0, 2, 5, 9, 19 and 180 of ensilage. Silages made without additive or with formic acid underwent contrasting but rapid, lactic acid dominant fermentations. Formic acid restricted fermentation, reducing (P\u3c 0.001) buffering capacity and the concentration of lactic acid and increasing (P\u3c 0.001) the concentration of water soluble carbohydrates. Counts of indigenous Enterobacteria were initially high (log10 8.1 cfu g-1) but declined rapidly in the early stages of ensilage and were not detected by day 19 of ensilage. Formic acid increased (P\u3c 0.05) the initial rate of decline in enterobacterial numbers. No indigenous E. coli 0157 were found on the ensiled grass. Inoculation with E. coli 0157:H7 increased (P\u3c 0.001) the numbers of this organism but they declined rapidly and were absent by day 5 of ensilage. The addition of formic acid accelerated (P\u3c 0.001) this rate of decline. The added E. coli did not alter (P\u3e 0.05) silage fermentation pattern

Measurements of μ→3e\mu\to 3e Decay with Polarised Muons as a Probe of New Physics

Working within the Standard Model effective field theory approach, we examine the possibility to test charged lepton flavour violating (cLFV) new physics (NP) by angular measurements of the outgoing electron and positrons in the polarised $\mu^{+}\to e^{+}e^{+}e^{-}$ decay. This decay is planned to be studied with a sensitivity to the branching ratio of $B_{\mu\to3e}\sim 10^{-15}$ by the Mu3e experiment at PSI. To illustrate the potential of these measurements, we consider a set of eight effective operators generating the decay at the tree level, including dimension-five dipole operators and dimension-six scalar and vector four-fermion operators of different chiralities. We show that if the polarised $\mu^{+}\to e^{+}e^{+}e^{-}$ decay is observed and is induced by a single operator, data from three angular observables - two P-odd asymmetries and one T-odd asymmetry - can allow to discriminate between all considered operators with the exception of scalar and vector operators of opposite chirality. For these two types of operators, the P-odd asymmetry is maximal in magnitude; they can be distinguished, in principle, by measuring the helicities of the outgoing positrons. The observation of a non-zero T-odd asymmetry would indicate the presence in the decay rate of a dipole and vector operator interference term that is T (CP) violating.Comment: 22 pages, 2 figures, 3 table

Phase Transitions in Quantum Dots

We perform Hartree-Fock calculations to show that quantum dots (i.e. two dimensional systems of up to twenty interacting electrons in an external parabolic potential) undergo a gradual transition to a spin-polarized Wigner crystal with increasing magnetic field strength. The phase diagram and ground state energies have been determined. We tried to improve the ground state of the Wigner crystal by introducing a Jastrow ansatz for the wavefunction and performing a variational Monte Carlo calculation. The existence of so called magic numbers was also investigated. Finally, we also calculated the heat capacity associated with the rotational degree of freedom of deformed many-body states.Comment: 14 pages, 7 postscript figure

How neutral is the intergalactic medium surrounding the redshift z=7.085 quasar ULAS J1120+0641?

The quasar ULAS J1120+0641 at redshift z=7.085 has a highly ionised near zone which is smaller than those around quasars of similar luminosity at z~6. The spectrum also exhibits evidence for a damping wing extending redward of the systemic Lya redshift. We use radiative transfer simulations in a cosmological context to investigate the implications for the ionisation state of the inhomogeneous IGM surrounding this quasar. Our simulations show that the transmission profile is consistent with an IGM in the vicinity of the quasar with a volume averaged HI fraction of f_HI>0.1 and that ULAS J1120+0641 has been bright for 10^6--10^7 yr. The observed spectrum is also consistent with smaller IGM neutral fractions, f_HI ~ 10^-3--10-4, if a damped Lya system in an otherwise highly ionised IGM lies within 5 proper Mpc of the quasar. This is, however, predicted to occur in only ~5 per cent of our simulated sight-lines for a bright phase of 10^6--10^7 yr. Unless ULAS J1120+0641 grows during a previous optically obscured phase, the low age inferred for the quasar adds to the theoretical challenge of forming a 2x10^9 M_sol black hole at this high redshift.Comment: 5 pages, 4 figures, accepted to MNRAS letter

The PubChem chemical structure sketcher

PubChem is an important public, Web-based information source for chemical and bioactivity information. In order to provide convenient structure search methods on compounds stored in this database, one mandatory component is a Web-based drawing tool for interactive sketching of chemical query structures. Web-enabled chemical structure sketchers are not new, being in existence for years; however, solutions available rely on complex technology like Java applets or platform-dependent plug-ins. Due to general policy and support incident rate considerations, Java-based or platform-specific sketchers cannot be deployed as a part of public NCBI Web services. Our solution: a chemical structure sketching tool based exclusively on CGI server processing, client-side JavaScript functions, and image sequence streaming. The PubChem structure editor does not require the presence of any specific runtime support libraries or browser configurations on the client. It is completely platform-independent and verified to work on all major Web browsers, including older ones without support for Web2.0 JavaScript objects

Corporate Hierarchies and the Size of Nations: Theory and Evidence

Corporate organization varies within a country and across countries with country size. The paper starts by establishing some facts about corporate organization based on unique data of 660 Austrian and German corporations. The larger country (Germany) has larger firms with flatter more decentral corporate hierarchies compared to the smaller country (Austria). Firms in the larger country change their organization less fast than firms in the smaller country. Over time firms have been introducing less hierarchical organizations by delegating power to lower levels of the corporation. We develop a theory which explains these facts and which links these features to the trade environment that countries and firms face. We introduce firms with internal hierarchies in a Krugman (1980) model of trade. We show that international trade and the toughness of competition in international markets induce a power struggle in firms which eventually leads to decentralized corporate hierarchies. We offer econometric evidence which is consistent with the models predictions

Modeling Operator Behavior in the Safety Analysis of Collaborative Robotic Applications

Human-Robot Collaboration is increasingly prominent in peo- ple's lives and in the industrial domain, for example in manufacturing applications. The close proximity and frequent physical contacts between humans and robots in such applications make guaranteeing suitable levels of safety for human operators of the utmost importance. Formal veri- cation techniques can help in this regard through the exhaustive explo- ration of system models, which can identify unwanted situations early in the development process. This work extends our SAFER-HRC method- ology with a rich non-deterministic formal model of operator behaviors, which captures the hazardous situations resulting from human errors. The model allows safety engineers to rene their designs until all plausi- ble erroneous behaviors are considered and mitigated

Survival of low-birth-weight infants at Baragwanath Hospital - 1950 - 1996

Objectives. To examine changes in survival rates among lowbirth- weight (LBW) infants between the years 1950 and 1996:Methods. Survival figures were analysed for LBW infants managed at Baragwanath Hospital, a tertiary care centre in Soweto, Johannesburg, over four periods spanning five decades.Results. The overall mortality rates of LBW infants decreased markedly between the early 1950s and the period 1995/96. By the mid-1990s approximately four times the number of infants with birth weight less than 1 500 g were surviving compared with the early 1950s. The reduction in mortality rates occurred in all LBW groups during the first three decades. However, since 1981 infants who weighed less than 1 500 g at birth were the major contributors to the overall reduction in mortality. Between the years 1981/82 and 1995/96, survival increased significantly from 64% to 79% for infants with birth weight 1 000 - 1 499 g, and from 14% to 32% for those with birth weight less than 1 000 g. Since infants in the latter group were seldom offered mechanical ventilation or artificial surfactant, a large part of these increases in survival can be attributed. to improvement in the general level of care.Conclusion. There have been dramatic improvements in the survival of LBW infants over this time period at Baragwanath Hospital. Although newer interventions such as mechanical ventilation and artificial surfactant have played a significant role, improvement in care at primary and secondary levels has been of major importance