Fluorescent visualization of a spreading surfactant

The spreading of surfactants on thin films is an industrially and medically important phenomenon, but the dynamics are highly nonlinear and visualization of the surfactant dynamics has been a long-standing experimental challenge. We perform the first quantitative, spatiotemporally-resolved measurements of the spreading of an insoluble surfactant on a thin fluid layer. During the spreading process, we directly observe both the radial height profile of the spreading droplet and the spatial distribution of the fluorescently-tagged surfactant. We find that the leading edge of spreading circular layer of surfactant forms a Marangoni ridge in the underlying fluid, with a trough trailing the ridge as expected. However, several novel features are observed using the fluorescence technique, including a peak in the surfactant concentration which trails the leading edge, and a flat, monolayer-scale spreading film which differs from concentration profiles predicted by current models. Both the Marangoni ridge and surfactant leading edge can be described to spread as $R \propto t^{\delta}$. We find spreading exponents, $\delta_H \approx 0.30$ and $\delta_\Gamma \approx 0.22$ for the ridge peak and surfactant leading edge, respectively, which are in good agreement with theoretical predictions of $\delta = 1/4$. In addition, we observe that the surfactant leading edge initially leads the peak of the Marangoni ridge, with the peak later catching up to the leading edge

The unitary ability of IQ and indexes in WAIS-IV

Lichtenberger and Kaufman (2009, p. 167) defined unitary ability as ‘an ability […] that is represented by a cohesive set of scaled scores, each reflecting slightly different or unique aspects of the ability’. Flanagan and Kaufman (2009) and Lichtenberger and Kaufman (2012) used a difference of 23 IQ points between the highest score (Max) and the lowest score (Min) obtained by a subject in the four Indexes of the WAIS-IV to define unitarity of the total IQ score. A similar method has been used to assess the unitary ability of the four Indexes, with a threshold of 5 points. Such difference scores (of 23 for IQ and 5 for Indexes) are considered high and infrequent and the authors therefore conclude that the corresponding Full-Scale IQ score or Index score is uninterpretable. In this paper we argue that these thresholds are inappropriate because they are based on the wrong standard deviation. The main aim of this study was to establish variability thresholds for IQ and the WAIS-IV Indexes for the American standardization sample and to compare these thresholds with those for the Italian standardization sample. We also consider an alternative approach to determining whether an IQ score represents a unitary ability, based on the maximum difference score for the 10 core subtests that contribute to Full-Scale IQ scores

Exotic glass types and the intensity of recycling in the northwest Quarter of Gerasa (Jerash, Jordan)

Major and trace elements are presented for 149 glass fragments ranging in date from the Roman to Early Islamic periods (1st – mid-8th centuries CE), excavated during the Danish-German Jerash Northwest Quarter Project's fieldwork between 2011 and 2016. The results confirm a clear dominance of Levantine glass types, but also reveal 12 glasses of Egyptian and Mesopotamian compositions recovered from two houses destroyed by the major earthquake which hit parts of the Levant in January 749 CE. These closed and undisturbed contexts from the final phase of occupation reveal the presence of relatively more pristine Levantine as well as imported material that is less visible in earlier contexts in the Gerasa assemblage, where the recycling indexes are high and chemical signatures of any exotic glass were largely lost due to remelting and their dilution by the overwhelming quantities of glass produced in the Levantine region. This emphasizes that imported glass may frequently be underestimated or even invisible in glass compositional studies, depending on the archaeological context sampled and the approach taken to artifact quantification. Levantine glass was attributed to Roman, Late Roman (Jalame) and Byzantine/Early Islamic (Apollonia) productions based primarily on MnO, Al_{2}O_{3} and Na_{2}O concentrations, which offered an advantage over previous approaches. While colorants in weakly colored glass indicate recycled material, their concentrations are sensitive to context, with higher concentrations in the early periods when the use of intentionally colored glass was more frequent. We have therefore developed the concept of the intensity of recycling, which was estimated using components modified during prolonged melting, such as K_{2}O, P_{2}O_{5} and Cl. A pronounced enrichment in CaO, also dependent upon the intensity of recycling, may affect the assignment to compositional groups and should be taken into consideration in future. Recycling in Gerasa appears to have been more intensive than was the case for cities closer to the primary production centers on the Mediterranean coast, consistent with the view that the dependency on recycling increases further away from the source of the primary material. In contrast, the cities in the coastal plain could readily exploit the marine transportation network, which appears to have played a major role in the distribution of raw glass

Copper-based metalwork in Roman to early Islamic Jerash (Jordan): Insights into production and recycling through alloy compositions and lead isotopes

Metallographic, chemical and lead isotopic analyses of copper-based artefacts recovered from the Northwest Quarter in Jerash (ancient Gerasa) in Jordan provide new information on the civic life and material culture from a key urban site in the Roman Empire's eastern provinces. The samples span the city's occupation from its flourishing under Roman rule into the Byzantine and early Islamic periods. We examined 49 copper-based artefacts using reflected light microscopy and micro-X-ray fluorescence. A subset of these artefacts was analysed by electron microprobe spectroscopy for major and minor elements at higher spatial resolution, and by multi-collector inductively coupled plasma mass spectrometry for lead isotopes. Results imply that binary bronze dominated the Roman period, (leaded) brass characterised the Byzantine period, while tin-containing alloys were prevalent during the Islamic period. Lead isotopes suggest that during the Roman and Byzantine periods some of the metal in Jerash came from European and/or Mediterranean sources, while copper used during the Islamic period may have been sourced more locally from Timna. The changes in alloy types and lead isotopes suggest that recycling of metals took place in Jerash possibly as early as the Roman period and more frequent from the Byzantine period onwards

An unusual VLF signature structure recorded by the DEMETER satellite

A type of electromagnetic phenomenon has been found in the electric VLF data measured by the low Earth orbit DEMETER satellite, which was nonidentified earlier as a different class of electromagnetic VLF events. The phenomenon, termed as “swallow-tailed whistler” (STW) after its shape, seems to be similar to a whistler, but following the main trace, an additional trace appears with monotonously increasing frequency. The secondary trace, lasting less than 80 ms within the recorded 20 kHz bandwidth joins at a given Starting Furcation Frequency. In a 7 month long time interval three series of strong STWs were found in a geographically confined search zone. Further, 10 weak STW periods have been identified by a thorough review of a 2 month long recording. Several STWs were found by the investigation of randomly selected DEMETER burst VLF recording acquired globally. On the basis of comparisons with previous studies, we can exclude that this phenomenon is generated by plasma processes in the vicinity of the satellite though the formation mechanism of this (ionospheric) signal is so far unclear. It is possible that this event type appeared in earlier records too, however, without identification

Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating

We model the photoelectric emission from and charging of interstellar dust and obtain photoelectric gas heating efficiencies as a function of grain size and the relevant ambient conditions. Using realistic grain size distributions, we evaluate the net gas heating rate for various interstellar environments, and find less heating for dense regions characterized by R_V=5.5 than for diffuse regions with R_V=3.1. We provide fitting functions which reproduce our numerical results for photoelectric heating and recombination cooling for a wide range of interstellar conditions. In a separate paper we will examine the implications of these results for the thermal structure of the interstellar medium. Finally, we investigate the potential importance of photoelectric heating in H II regions, including the warm ionized medium. We find that photoelectric heating could be comparable to or exceed heating due to photoionization of H for high ratios of the radiation intensity to the gas density. We also find that photoelectric heating by dust can account for the observed variation of temperature with distance from the galactic midplane in the warm ionized medium.Comment: 50 pages, including 18 figures; corrected title and abstract field

Quantum Effects in Small-Capacitance Single Josephson Junctions

We have measured the current-voltage (I-V) characteristics of small-capacitance single Josephson junctions at low temperatures (T=0.02-0.6 K), where the strength of the coupling between the single junction and the electromagnetic environment was controlled with one-dimensional arrays of dc SQUIDs. The single-junction I-V curve is sensitive to the impedance of the environment, which can be tuned IN SITU. We have observed Coulomb blockade of Cooper-pair tunneling and even a region of negative differential resistance, when the zero-bias resistance R_0' of the SQUID arrays is much higher than the quantum resistance R_K = h/e^2 = 26 kohm. The negative differential resistance is evidence of coherent single-Cooper-pair tunneling within the theory of current-biased single Josephson junctions. Based on the theory, we have calculated the I-V curves numerically in order to compare with the experimental ones at R_0' >> R_K. The numerical calculation agrees with the experiments qualitatively. We also discuss the R_0' dependence of the single-Josephson-junction I-V curve in terms of the superconductor-insulator transition driven by changing the coupling to the environment.Comment: 11 pages with 14 embedded figures, RevTeX4, final versio

Integrated heterodyne array receivers for submillimeter astronomy

The advent of large format (~100 pixel) spectroscopic imaging cameras at submillimeter wavelengths would fundamentally change the way in which astronomy is performed in this important wavelength regime. While the possibility of such instruments has been discussed for more than two decades, only recently have advances in mixer technology, device fabrication, micromachining, digital signal processing, and telescope design made the construction of such an instrument possible and economical. In our paper, we will present the design concept for a 10×10 heterodyne camera

The CAT-ACT Beamline at ANKA: A new high energy X-ray spectroscopy facility for CATalysis and ACTinide research

A new hard X-ray beamline for CATalysis and ACTinide research has been built at the synchrotron radiation facility ANKA. The beamline design is dedicated to X-ray spectroscopy, including ‘flux hungry’ photon-in/photon-out and correlative techniques with a special infrastructure for radionuclide and catalysis research. The CAT-ACT beamline will help serve the growing need for high flux/hard X-ray spectroscopy in these communities. The design, the first spectra and the current status of this project are reported

La hematuria vesical bovina en Colombia: estudios morfológicos, estructura y ultraestructura.

El trabajo tiene como fin clarificar el tipo de lesiones asociadas con la hematuria vesical bovina. Se describen los cambios morfológicos observados mediante la utilización de microscopía de luz y microscopía electrónica, tanto en animales experimentales como en casos de ocurrencia natural. Para el estudio de casos de ocurrencia natural, con el fin de obtener biópsias vesicales para estudios de microscopía de luz, microscopía electrónica y para lograr una evaluación comparativa de la patología de las lesiones de casos de ocurrencia natural y experimentales, se estudiaron 2 vacas Holstein adultas con hematuria, provenientes de una región hiperendémica. De cada una se tomaron 20 biópsias vesicales ciegas con un citoscopio de uso humano y con un fibrogastroscopio con visión derecha. Para el estudio de casos experimentales se estudiaron 3 bovinos, 2 machos y una hembra, raza Holstein, sirviendo un cuarto animal como control. A estos animales se les suministró un kilogramo diario de una mezcla de helecho desecado (Pteridium aquilinum, var. Arachnoidea), con una ración diaria de pastos y ensilaje. Los animales fueron sometidos a necropsia obteniéndose muestras de epitelio para estudios de microscopía electrónica y de todos los tejidos para microscopía de luz. Las lesiones halladas van desde cistitis hasta neoplasias de origen vascular y epitelial. Los hallazgos permiten demostrar que en la mayoría de los casos estudiados en Colombia, las lesiones de hematuria son de tipo vascular, a diferencia de otros reportes Los hallazgos ultraestructurales hacen pensar en un proceso de naturaleza tóxica, no habiéndose podido demostrar la presencia de partículas viralesGanado de leche-Ganadería lech