Assembling the puzzle of superconducting elements: A Review

Superconductivity in the simple elements is of both technological relevance and fundamental scientific interest in the investigation of superconductivity phenomena. Recent advances in the instrumentation of physics under pressure have enabled the observation of superconductivity in many elements not previously known to superconduct, and at steadily increasing temperatures. This article offers a review of the state of the art in the superconductivity of elements, highlighting underlying correlations and general trends.Comment: Review, 10 pages, 11 figures, 97 references; to appear in Superc. Sci. Techno

A strategy for implementing non-perturbative renormalisation of heavy-light four-quark operators in the static approximation

We discuss the renormalisation properties of the complete set of $\Delta B = 2$ four-quark operators with the heavy quark treated in the static approximation. We elucidate the role of heavy quark symmetry and other symmetry transformations in constraining their mixing under renormalisation. By employing the Schroedinger functional, a set of non-perturbative renormalisation conditions can be defined in terms of suitable correlation functions. As a first step in a fully non-perturbative determination of the scale-dependent renormalisation factors, we evaluate these conditions in lattice perturbation theory at one loop. Thereby we verify the expected mixing patterns and determine the anomalous dimensions of the operators at NLO in the Schroedinger functional scheme. Finally, by employing twisted-mass QCD it is shown how finite subtractions arising from explicit chiral symmetry breaking can be avoided completely.Comment: 41 pages, 6 figure

Hf–Zr anomalies in clinopyroxene from mantle xenoliths from France and Poland: implications for Lu–Hf dating of spinel peridotite lithospheric mantle

Clinopyroxenes in some fresh anhydrous spinel peridotite mantle xenoliths from the northern Massif Central (France) and Lower Silesia (Poland), analysed for a range of incompatible trace elements by laser ablation inductively coupled plasma mass spectrometry, show unusually strong negative anomalies in Hf and Zr relative to adjacent elements Sm and Nd, on primitive mantle-normalised diagrams. Similar Zr–Hf anomalies have only rarely been reported from clinopyroxene in spinel peridotite mantle xenoliths worldwide, and most are not as strong as the examples reported here. Low Hf contents give rise to a wide range of Lu/Hf ratios, which over geological time would result in highly radiogenic εHf values, decoupling them from εNd ratios. The high 176Lu/177Hf could in theory produce an isochronous relationship with 176Hf/177Hf over time; an errorchron is shown by clinopyroxene from mantle xenoliths from the northern Massif Central. However, in a review of the literature, we show that most mantle spinel peridotites do not show such high Lu/Hf ratios in their constituent clinopyroxenes, because they lack the distinctive Zr–Hf anomaly, and this limits the usefulness of the application of the Lu–Hf system of dating to garnet-free mantle rocks. Nevertheless, some mantle xenoliths from Poland or the Czech Republic may be amenable to Hf-isotope dating in the future

Фотоиндуцированные процессы наночастиц оксида железа для усиления лазерной терапии

Nanoparticles are used as drug carriers to increase the selectivity and effectiveness of therapy, as well as for combined therapy that utilizes different effects. Iron oxide nanoparticles are promising in this aspect. Due to magnetic properties, they can be used as a contrast agent for magnetic resonance imaging. Also, iron oxide nanoparticles could be coated with a photosensitizer for photodynamic therapy and their laser or magnetic heating can be used for phototherapy. Local enhancement of the electromagnetic field near iron oxide nanoparticles can increase the fluorescence intensity of photosensitizers and the efficiency of singlet oxygen generation. This paper presents the results of a study of iron oxide nanoparticles focused on the photophysical aspects of the formation of “hot spots” under laser irradiation. The photoinduced effects of iron oxide nanoparticles observed in in vitro experiments lead to the rupture of lysosomes. Theoretical modeling showed that the heating of iron oxide nanoparticles with a radius of 35 nm under the action of laser radiation is about 89°C and 19°C for wavelengths of 458 and 561 nm, respectively. Local field enhancement occurs in pairs of nanoparticles of various sizes and strongly depends on the distance between them. The maximum gain is achieved at small distances between nanoparticles. For a dimer of nanoparticles with radii of 10 and 35 nm at a distance of 1 nm, an enhancement factor of two orders of magnitude was obtained. The investigated phenomenon of «hot spots» is in demand for precision therapy, because the photo-induced processes occur at small distances between nanoparticles, in areas of their high accumulation.Наночастицы используются в качестве носителей лекарственных средств для повышения селективности и эффективности терапии, а также для сочетанной терапии, объединяющей разные виды воздействия. Перспективными в этом аспекте являются наночастицы оксида железа. Благодаря магнитным свойствам, они могут быть применяться в качестве контраста для магнитно-резонансной томографии. Также наночастицы оксида железа могут быть покрыты фотосенсибилизатором для фотодинамической терапии, а их лазерный или магнитный нагрев этих частиц может используется для проведения фототерапии. При этом локальное усиление электромагнитного поля вблизи наночастиц оксида железа может повысить интенсивность флуоресценции фотосенсибилизаторов и эффективность генерации синглетного кислорода.В работе представлены результаты исследования наночастиц оксида железа, сфокусированного на фотофизических аспектах образования «горячих точек» при лазерном облучении. Фотоиндуцированные эффекты наночастиц оксида железа, наблюдаемые в экспериментах in vitro, приводят к разрыву лизосом. Теоретическое моделирование показало, что нагрев наночастиц оксида железа радиусом 35 нм под действием лазерного излучения составляет порядка 89˚С и 19˚С для длин волн 458 и 561 нм, соответственно. Локальное усиление поля возникает в парах из наночастиц различного размера и сильно зависит от расстояния между ними. Максимальное усиление достигается при малых расстояниях между наночастицами. Для димера наночастиц с радиусами 10 нм и 35 нм на расстоянии 1 нм получен фактор усиления на два порядка. Рассмотренное явление «горячих точек» востребовано для прецизионной терапии, так как фотоиндуцированные процессы возникают на малых расстояниях между наночастицами, в областях с их высоким накоплением

Chaotic lensing around boson stars and Kerr black holes with scalar hair

In a recent paper [P. V. P. Cunha, C. A. R. Herdeiro, E. Radu, and H. F. Runarsson, Phys. Rev. Lett. 115, 211102 (2015).], it was shown that the lensing of light around rotating boson stars and Kerr black holes with scalar hair can exhibit chaotic patterns. Since no separation of variables is known (or expected) for geodesic motion on these backgrounds, we examine the 2D effective potentials for photon trajectories, to obtain a deeper understanding of this phenomenon. We find that the emergence of stable light rings on the background spacetimes allows the formation of " pockets" in one of the effective potentials, for open sets of impact parameters, leading to an effective trapping of some trajectories, dubbed " quasibound orbits." We conclude that pocket formation induces chaotic scattering, although not all chaotic orbits are associated to pockets. These and other features are illustrated in a gallery of examples, obtained with a new ray- tracing code, PYHOLE, which includes tools for a simple, simultaneous visualization of the effective potential, together with the spacetime trajectory, for any given point in a lensing image. An analysis of photon orbits allows us to further establish a positive correlation between photon orbits in chaotic regions and those with more than one turning point in the radial direction; we recall that the latter is not possible around Kerr black holes. Moreover, we observe that the existence of several light rings around a horizon (several fundamental orbits, including a stable one), is a central ingredient for the existence of multiple shadows of a single hairy black hole. We also exhibit the lensing and shadows by Kerr black holes with scalar hair, observed away from the equatorial plane, obtained with PYHOLE

Evaluation des Pilotprojektes Qualifizierungsverbünde (QV) zur Sicherung der Beschäftigungsfähigkeit. Abschlussbericht (Berichtszeitraum: 01.06.2020-31.08.2021)

Vor allem Kleinst-, Klein- und mittelständische Betriebe (KMU) haben Schwierigkeiten dabei, branchen- und betriebsspezifische Kompetenzbedarfe zu identifizieren und passende Qualifizierungsmaßnahmen für ihre Beschäftigten zu finden. Es mangelt dafür häufig an entsprechendem Fachpersonal und an den erforderlichen finanziellen Mitteln. Hilfe erhalten Firmen von Qualifizierungsverbünden (QV). In QV schließen sich verschiedene Firmen, Verbände und Institutionen zu regionalen Netzwerken zusammen, die gemeinsame Weiterbildungsangebote für Beschäftigte der Branchen, aber auch branchenübergreifend planen und durchführen. Die hauptamtlich in den QV eingesetzten Expert*innen haben im Blick, welche Skills zukünftig nachgefragt werden und wo es entsprechende Trainings gibt. Teilweise werden Kurse sogar selbst entwickelt. Außerdem können die Qualifizierungsverbünde dazu beitragen, dass sich betroffene Unternehmen in einer Region besser vernetzen und über die zukünftigen Herausforderungen austauschen. Der Vernetzungsansatz bildet in fast allen Verbünden das Herzstück der Zusammenarbeit. Entscheidend für den Erfolg der Netzwerkarbeit ist die Leistung der Verbundmanager*innen. Diese steuern operativ das Netzwerkmanagement. Sie halten persönliche Kontakte und sichern den Informationsfluss. Sie verantworten überdies in Rückkopplung mit den Verbundpartnern die strategische Weiterentwicklung. Das sind Ergebnisse der Evaluation des Pilotprojektes "Qualifizierungsverbünde zur Sicherung der Beschäftigungsfähigkeit", die das Forschungsinstitut Betriebliche Bildung (f-bb) im Auftrag des Bildungswerks der Baden-Württembergischen Wirtschaft durchgeführt hat. Ziel der Evaluation war es, Erfolgsfaktoren und Hindernisse eines nachhaltigen Projekterfolgs zu identifizieren und im Hinblick auf eine zweite Projektphase Erkenntnisse zur Weiterentwicklung, Verstetigung und Ausweitung von Qualifizierungsverbünden zu gewinnen. (DIPF/Orig.

Heavy Baryon Specroscopy from the Lattice

The results of an exploratory lattice study of heavy baryon spectroscopy are presented. We have computed the full spectrum of the eight baryons containing a single heavy quark, on a $24^3\times 48$ lattice at $\beta=6.2$, using an $O(a)$-improved fermion action. We discuss the lattice baryon operators and give a method for isolating the contributions of the spin doublets $(\Sigma,\Sigma^*)$, $(\Xi',\Xi^*)$ and $(\Omega,\Omega^*)$ to the correlation function of the relevant operator. We compare our results with the available experimental data and find good agreement in both the charm and the beauty sectors, despite the long extrapolation in the heavy quark mass needed in the latter case. We also predict the masses of several undiscovered baryons. We compute the \Lambda-\mbox{pseudoscalar meson} and $\Sigma-\Lambda$ mass splittings. Our results, which have errors in the range $10-30\%$, are in good agreement with the experimental numbers. For the $\Sigma^*-\Sigma$ mass splitting, we find results considerably smaller than the experimental values for both the charm and the beauty baryons, although in the latter case the experimental results are still preliminary. This is also the case for the lattice results for the hyperfine splitting for the heavy mesons.Comment: 31 pages LaTex, with postscript figures include

Heavy Quark Spectroscopy and Matrix Elements: A Lattice Study using the Static Approximation

We present results of a lattice analysis of the $B$ parameter, $B_B$, the decay constant $f_B$, and several mass splittings using the static approximation. Results were obtained for 60 quenched gauge configurations computed at $\beta=6.2$ on a lattice size of $24^3\times48$. Light quark propagators were calculated using the $O(a)$-improved Sheikholeslami-Wohlert action. We find \Bbstat(m_b) = 0.69\er{3}{4} {\rm(stat)}\er{2}{1} {\rm(syst)}, corresponding to \Bbstat = 1.02\er{5}{6}\er{3}{2}, and \fbstat = 266\err{18}{20}\err{28}{27} \mev, f_{B_s}^2 B_{B_s}/f_B^2 B_B = 1.34\er{9}{8}\er{5}{3}, where a variational fitting technique was used to extract \fbstat. For the mass splittings we obtain M_{B_s}-M_{B_d} = 87\err{15}{12}\err{6}{12} \mev, M_{\Lambda_b}-M_{B_d} = 420\errr{100}{90}\err{30}{30} \mev and M_{B^*}^2-M_B^2 = 0.281\err{15}{16}\err{40}{37} \gev^2. We compare different smearing techniques intended to improve the signal/noise ratio. From a detailed assessment of systematic effects we conclude that the main systematic uncertainties are associated with the renormalisation constants relating a lattice matrix element to its continuum counterpart. The dependence of our findings on lattice artefacts is to be investigated in the future.Comment: 40 pages, uuencoded compressed tar file, containing one LaTeX file and 14 postscript files (to be included with epsf). Minor change in the value of the B parameter. Contains corrected value for the B*-B mass splitting. Version accepted for publication in Phys. Rev.

Overview of Plasma Lens Experiments and Recent Results at SPARC_LAB

Beam injection and extraction from a plasma module is still one of the crucial aspects to solve in order to produce high quality electron beams with a plasma accelerator. Proper matching conditions require to focus the incoming high brightness beam down to few microns size and to capture a high divergent beam at the exit without loss of beam quality. Plasma-based lenses have proven to provide focusing gradients of the order of kT/m with radially symmetric focusing thus promising compact and affordable alternative to permanent magnets in the design of transport lines. In this paper an overview of recent experiments and future perspectives of plasma lenses is reported