Theory for the ultrafast ablation of graphite films

The physical mechanisms for damage formation in graphite films induced by femtosecond laser pulses are analyzed using a microscopic electronic theory. We describe the nonequilibrium dynamics of electrons and lattice by performing molecular dynamics simulations on time-dependent potential energy surfaces. We show that graphite has the unique property of exhibiting two distinct laser induced structural instabilities. For high absorbed energies (> 3.3 eV/atom) we find nonequilibrium melting followed by fast evaporation. For low intensities above the damage threshold (> 2.0 eV/atom) ablation occurs via removal of intact graphite sheets.Comment: 5 pages RevTeX, 3 PostScript figures, submitted to Phys. Re

Theory for the Ultrafast Structural Response of optically excited small clusters: Time-dependence of the Ionization Potential

Combining an electronic theory with molecular dynamics simulations we present results for the ultrafast structural changes in small clusters. We determine the time scale for the change from the linear to a triangular structure after the photodetachment process Ag$_3^- \rightarrow {\rm Ag}_3$. We show that the time-dependent change of the ionization potential reflects in detail the internal degrees of freedom, in particular coherent and incoherent motion, and that it is sensitive to the initial temperature. We compare with experiment and point out the general significance of our results.Comment: 10 pages, Revtex, 3 postscript figure

Dynamic nuclear polarization and spin-diffusion in non-conducting solids

There has been much renewed interest in dynamic nuclear polarization (DNP), particularly in the context of solid state biomolecular NMR and more recently dissolution DNP techniques for liquids. This paper reviews the role of spin diffusion in polarizing nuclear spins and discusses the role of the spin diffusion barrier, before going on to discuss some recent results.Comment: submitted to Applied Magnetic Resonance. The article should appear in a special issue that is being published in connection with the DNP Symposium help in Nottingham in August 200

Long-Term Persistance of the Pathophysiologic Response to Severe Burn Injury

Main contributors to adverse outcomes in severely burned pediatric patients are profound and complex metabolic changes in response to the initial injury. It is currently unknown how long these conditions persist beyond the acute phase post-injury. The aim of the present study was to examine the persistence of abnormalities of various clinical parameters commonly utilized to assess the degree hypermetabolic and inflammatory alterations in severely burned children for up to three years post-burn to identify patient specific therapeutic needs and interventions. Nine-hundred seventy-seven severely burned pediatric patients with burns over 30% of the total body surface admitted to our institution between 1998 and 2008 were enrolled in this study and compared to a cohort non-burned, non-injured children. Demographics and clinical outcomes, hypermetabolism, body composition, organ function, inflammatory and acute phase responses were determined at admission and subsequent regular intervals for up to 36 months post-burn. Statistical analysis was performed using One-way ANOVA, Student's t-test with Bonferroni correction where appropriate with significance accepted at p<0.05. Resting energy expenditure, body composition, metabolic markers, cardiac and organ function clearly demonstrated that burn caused profound alterations for up to three years post-burn demonstrating marked and prolonged hypermetabolism, p<0.05. Along with increased hypermetabolism, significant elevation of cortisol, catecholamines, cytokines, and acute phase proteins indicate that burn patients are in a hyperinflammatory state for up to three years post-burn p<0.05. Severe burn injury leads to a much more profound and prolonged hypermetabolic and hyperinflammatory response than previously shown. Given the tremendous adverse events associated with the hypermetabolic and hyperinflamamtory responses, we now identified treatment needs for severely burned patients for a much more prolonged time

Atacamite Cu2Cl(OH)3: A model compound for the S = 1/2 sawtooth chain?

We present a combined experimental and theoretical study of the mineral atacamite Cu2Cl(OH)3.Based on ab initio band structure calculations, we derive a magnetic coupling scheme of essentially a S = 1/2 sawtooth chain. Experimentally, we fully characterize the long-range antiferromagnetically ordered state and field-induced behavior, here for H k b axis. Magnetic order is suppressed by magnetic fields of ∼ 20 T, while beginning at 31.5 T we observe a wide magnetization plateau at half of the saturation magnetization, Msat/2. Numerical calculations for the magnetization M(H) of the quantum sawtooth chain reveal a plateau at Msat/2, raising the issue of the understandingof its microscopic nature.Fil: Heinze, L.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Jeschke, H.. Okayama University; Japón. Goethe Universitat Frankfurt; AlemaniaFil: Metavitsiadis, A.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Reehuis, M.. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH; AlemaniaFil: Feyerherm, R.. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH; AlemaniaFil: Hoffmann, J. U.. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH; AlemaniaFil: Wolter, A. U. B.. Leibniz Institute For Solid State And Materials Researc; AlemaniaFil: Ding, X.. Los Alamos National High Magnetic Field Laboratory; Estados UnidosFil: Zapf, V.. Los Alamos National High Magnetic Field Laboratory; Estados UnidosFil: Corvalán Moya, Carolina del Huerto. Comisión Nacional de Energía Atómica; Argentina. Los Alamos National High Magnetic Field Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Weickert, F.. Los Alamos National High Magnetic Field Laboratory; Estados UnidosFil: Jaime, M.. Los Alamos National High Magnetic Field Laboratory; Estados UnidosFil: Rule, K. C.. Australian Nuclear Science And Technology Organisation; AustraliaFil: Menzel, D.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Valenti, R.. Goethe Universitat Frankfurt; AlemaniaFil: Brenig, W.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; AlemaniaFil: Süllow, S.. Technische Universitat Carolo Wilhelmina Zu Braunschweig.; Alemani

The Main Results of the Borexino Experiment

The main physical results on the registration of solar neutrinos and the search for rare processes obtained by the Borexino collaboration to date are presented.Comment: 8 pages, 8 figgures, To be published as Proceedings of the Third Annual Large Hadron Collider Physics Conference, St. Petersburg, Russia, 201

Engineering coherent interactions in molecular nanomagnet dimers

Proposals for systems embodying condensed matter spin qubits cover a very wide range of length scales, from atomic defects in semiconductors all the way to micron-sized lithographically defined structures. Intermediate scale molecular components exhibit advantages of both limits: like atomic defects, large numbers of identical components can be fabricated; as for lithographically defined structures, each component can be tailored to optimise properties such as quantum coherence. Here we demonstrate what is perhaps the most potent advantage of molecular spin qubits, the scalability of quantum information processing structures using bottom-up chemical self-assembly. Using Cr7Ni spin qubit building blocks, we have constructed several families of two-qubit molecular structures with a range of linking strategies. For each family, long coherence times are preserved, and we demonstrate control over the inter-qubit quantum interactions that can be used to mediate two-qubit quantum gates