Generation of broad XUV continuous high harmonic spectra and isolated attosecond pulses with intense mid-infrared lasers

We present experimental results showing the appearance of a near-continuum in the high-order harmonic generation (HHG) spectra of atomic and molecular species as the driving laser intensity of an infrared pulse increases. Detailed macroscopic simulations reveal that these near-continuum spectra are capable of producing IAPs in the far field if a proper spatial filter is applied. Further, our simulations show that the near-continuum spectra and the IAPs are a product of strong temporal and spatial reshaping (blue shift and defocusing) of the driving field. This offers a possibility of producing IAPs with a broad range of photon energy, including plateau harmonics, by mid-IR laser pulses even without carrier-envelope phase stabilization.Comment: 7 pages, 5 figures, submitted to J.Phys. B (Oct 2011

Experimental Observation of “Shadowing” in Optical Transition Radiation

We report the observation of shadowing between two optical transition radiation (OTR) sources from a 205 MeV electron beam. The total optical intensity is measured as a function of the distance $d$ between the sources, covering the range $0 \lt d \lt 4L_{\nu}$, where $L_{\nu}$ is the formation length of the particles. Data show that the total optical intensity starts decreasing due to shadowing when $d$ approaches $L_{\nu}$ until it becomes undetectable for very short distances $d/L_{\nu} \rightarrow 0$. A model based solely on interference between the two OTR sources is in good agreement with experimental data. To the knowledge of the authors this is the first systematic experimental observation of shadowing in OTR

Visual Similarity Perception of Directed Acyclic Graphs: A Study on Influencing Factors

While visual comparison of directed acyclic graphs (DAGs) is commonly encountered in various disciplines (e.g., finance, biology), knowledge about humans' perception of graph similarity is currently quite limited. By graph similarity perception we mean how humans perceive commonalities and differences in graphs and herewith come to a similarity judgment. As a step toward filling this gap the study reported in this paper strives to identify factors which influence the similarity perception of DAGs. In particular, we conducted a card-sorting study employing a qualitative and quantitative analysis approach to identify 1) groups of DAGs that are perceived as similar by the participants and 2) the reasons behind their choice of groups. Our results suggest that similarity is mainly influenced by the number of levels, the number of nodes on a level, and the overall shape of the graph.Comment: Graph Drawing 2017 - arXiv Version; Keywords: Graphs, Perception, Similarity, Comparison, Visualizatio

Cassini Observes the Active South Pole of Enceladus

Cassini has identified a geologically active province at the south pole of Saturn's moon Enceladus. In images acquired by the Imaging Science Subsystem (ISS), this region is circumscribed by a chain of folded ridges and troughs at ∼55°S latitude. The terrain southward of this boundary is distinguished by its albedo and color contrasts, elevated temperatures, extreme geologic youth, and narrow tectonic rifts that exhibit coarse-grained ice and coincide with the hottest temperatures measured in the region. Jets of fine icy particles that supply Saturn's E ring emanate from this province, carried aloft by water vapor probably venting from subsurface reservoirs of liquid water. The shape of Enceladus suggests a possible intense heating epoch in the past by capture into a 1:4 secondary spin/orbit resonance

The type and frequency of interactions that occur between staff and children outside in Early Years Foundation Stage settings during a fixed playtime period when there are tricycles available

This study reports on an investigation into adult and child interactions observed in the outdoor play environment in four Local Authority early years foundation stage settings in England. In this instance the common two features across the settings were the presence of tricycles and a timetabled outdoor play period. In total, across the four schools, there were 204 children. The study aimed to gain an understanding of the nature of the dialogues between staff and children, that is, the types of exchange that occurred when either the child approached an adult or the adult approached a child. The most frequent type of utterance was also analysed. The study concludes that adults in these settings spoke more than children and the greatest type of utterance was that of the adult about domestic matters. When the child initiated the conversation there were more extended child utterances than domestic utterances. This may suggest that children wish to be involved in conversations of depth and meaning and that staff need to become aware of how to develop this conversational language with children

The influence of maternal obesity on macrophage subsets in the human decidua

Obesity is seen as a low grade inflammatory state, and is associated with adverse pregnancy outcomes. Disturbed macrophage characteristics might be essential in obesity associated pregnancy pathology via effects on the regulation of angiogenesis and placental development. This study aims to address the effects of maternal obesity on macrophage subsets in the decidua of women with term uncomplicated pregnancies. Macrophages were isolated from the decidua basalis and decidua parietalis of women with pre-gravid BMI <25 (control) and BMI > 30 (obese). Macrophages were characterized and quantified using multi-color flow cytometry. Placentas of 10 obese and 10 control women after an uncomplicated term pregnancy were included. The decidua parietalis, but not decidua basalis, showed significantly lower levels of M1-type (HLA-DR+, CD163(-)) macrophages (p <0.05) in obese women (4,3% of total macrophages) compared to control women (5,3% of total macrophages). The lower levels of M1 macrophages, considered to be pro-inflammatory, might indicate a mechanism to compensate for the pro-inflammatory environment in obese women to ensure healthy pregnancy outcomes

Unstable Flow and Non-Monotonic Constitutive Equation of Transient Networks

We have measured the nonlinear rheological response of a model transient network over a large range of steady shear rates. The system is built up from an oil in water droplet microemulsion into which a telechelic polymer is incorporated. The phase behaviour is characterized which comprises a liquid-gas phase separation and a percolation threshold. The rheological measurements are performed in the one phase region above the percolation line. Shear thinning is observed for all samples, leading in most cases to an unstable stress response at intermediate shear rates. We built up a very simple mean field model which involves the reduction of the residence time of the stickers in the droplets due to the chain tensions at high shear. The computed constitutive equation is non-monotonic with a range where the stress is a decreasing function of the rate, a feature that indeed makes homogeneous flows unstable. The computed the flow curves compare well to the experiments.Comment: mai 200

Regularity Properties and Pathologies of Position-Space Renormalization-Group Transformations

We reconsider the conceptual foundations of the renormalization-group (RG) formalism, and prove some rigorous theorems on the regularity properties and possible pathologies of the RG map. Regarding regularity, we show that the RG map, defined on a suitable space of interactions (= formal Hamiltonians), is always single-valued and Lipschitz continuous on its domain of definition. This rules out a recently proposed scenario for the RG description of first-order phase transitions. On the pathological side, we make rigorous some arguments of Griffiths, Pearce and Israel, and prove in several cases that the renormalized measure is not a Gibbs measure for any reasonable interaction. This means that the RG map is ill-defined, and that the conventional RG description of first-order phase transitions is not universally valid. For decimation or Kadanoff transformations applied to the Ising model in dimension $d \ge 3$, these pathologies occur in a full neighborhood $\{ \beta > \beta_0 ,\, |h| < \epsilon(\beta) \}$ of the low-temperature part of the first-order phase-transition surface. For block-averaging transformations applied to the Ising model in dimension $d \ge 2$, the pathologies occur at low temperatures for arbitrary magnetic-field strength. Pathologies may also occur in the critical region for Ising models in dimension $d \ge 4$. We discuss in detail the distinction between Gibbsian and non-Gibbsian measures, and give a rather complete catalogue of the known examples. Finally, we discuss the heuristic and numerical evidence on RG pathologies in the light of our rigorous theorems.Comment: 273 pages including 14 figures, Postscript, See also ftp.scri.fsu.edu:hep-lat/papers/9210/9210032.ps.

Femtosecond Near Edge X-ray Absorption Measurement of the VO2Phase Transition

We measure the insulator-to-metal transition in VO2 using femtosecond Near-Edge X-ray Absorption. Sliced pulses of synchrotron radiation are used to detect the photo-induced dynamics at the 516-eV Vanadium L-3 edge

Performance of the first prototype of the CALICE scintillator strip electromagnetic calorimeter

A first prototype of a scintillator strip-based electromagnetic calorimeter was built, consisting of 26 layers of tungsten absorber plates interleaved with planes of 45x10x3 mm3 plastic scintillator strips. Data were collected using a positron test beam at DESY with momenta between 1 and 6 GeV/c. The prototype's performance is presented in terms of the linearity and resolution of the energy measurement. These results represent an important milestone in the development of highly granular calorimeters using scintillator strip technology. This technology is being developed for a future linear collider experiment, aiming at the precise measurement of jet energies using particle flow techniques