Brothers' group photograph

Abstract

One of the earliest examples of a composite print of a group was made by 0. G. Rejlander. In a lecture to the South London Photographic Society in 1863 he explained:

My first attempt at ‘double printing’ as some call it, was exhibited in London in 1855. It was named in the catalogue Groupe Printed from Three Negatives. That plan I hit upon through sheer vexation, because I could not get a gentleman's figure in focus, though he was close behind a sofa on which two ladies were seated.¹     

Early Photographs of Albania and Macedonia by Josef Székely

Abstract

Fifty photographs of Albania and Macedonia, taken in 1863 by Dr Josef Szekely, a 25-year-old chemist and photographer from Vienna, are important for their early date, their subject matter and their quality. They deserve attention also because of their novelty. Until now, these photographs have been unknown even to students of Albanian photography.¹ Székely's photographs include the first pictures ever taken in Albania and among the earliest known of Macedonia. Two 1864 photographs of the northern Albanian city of Shkodra have been called the first pictures taken in Albania,² but Székely took eight photographs there no later than September 1863, and by mid-October he had also photographed the Albanian towns of Prizren, Dibra and Ochrid. For historians of 144 ISSN 0308-7298 © 2003 Taylor & Francis Ltd. photography, as well as for historians of the Ottoman Balkans, Szekely's cityscapes, landscapes and portraits are a valuable and unknown resource.     

Roland G. Rood

Abstract

Roland G. Rood (1863–1927) is an enigmatic, yet fascinating, figure in the history of American art criticism. Very little about his education and career is known. His published writings as well as unpublished drafts for essays on aesthetics, however, provide a comprehensive framework for his ideas. Dating or referring to the period 1904–1907, this body of work indexes a significant direction of change in the relationship of art to science. Featured in Alfred Stieglitz's avant-garde journal Camera Work, Rood's criticism also illuminates the probing, psychological, and intertextural nature of Stieglitz's modernism.     

Original Talbot photographs in Estonia

Abstract

On the 25th September 1934, the Estonian newspaper Postimees published an interesting article concerning one of the founders of photography, W. H. F. Talbot.¹ Talbot's granddaughter, Miss Matilda Talbot, visited Estonia from the 17th September until the 1st October of that year, and the article was about her visit as well as her grandfather. She was the guest of Mrs Hünerson, Chief Commissioner of the Estonian Girl Guides, who had been in England that summer to attend a Girl Guide conference, and had been introduced to Miss Talbot at Lacock Abbey by a mutual acquaintance. Miss Talbot spent her time mainly at Tartu, but she also visited Petseri and Voru, small towns in southern Estonia, about 60 – 80 kilometres from that city. She was later to include a delightful account of her impressions of this Estonian holiday in one chapter of her memoirs.²     

Relation between work of adhesion and work of fracture for simple interfaces

A study was conducted of the relation between work of adhesion and work of fracture for adhesive-substrate systems exhibiting fracture at the interface. Materials and test conditions were selected to eliminate contributions from irreversible, energy-consuming processes in the bulk of the adhesive or substrate. Values for W _a were determined from contact angle measurements made at room temperature with the adhesive in the liquid state; values for F were determined from inverted blister tests conducted at temperatures low enough for the adhesive to be in the solid state. The independent variable, W _a, ranged from about 40 mJ/m² to 144 mJ/m². The dependent variable, F, was found to range from 0.12 J/m² to 20 J/m², with most under 5 J/m². The excess of F over W _a was found to increase exponentially with W _a, and was proof of the occurrence of irreversible processes in specimens as they were loaded and fractured. The exponential behavior of (F – W _a) with W _a suggested that the irreversible process was orientation hardening. The absence of detectable permanent deformation of any kind in the bulk substrates or at the fracture surfaces, plus the incapability of the adhesives to sustain significant irreversible processes, led to the conclusion that the orientation hardening must have taken place in the substrate, within a thin layer (and small volume) adjacent to the interfacial plane.     

Numerical study of the remittances of axially excited chiral sculptured zirconia thin films

The transmission and reflection spectra from a right-handed chiral sculptured zirconia thin film are calculated using the coupled wave theory and the Bruggeman homogenization formalism in conjunction with the experimental data for the relative dielectric constant of zirconia thin film. The dielectric dispersion function effect on these spectra appeared in wavelengths shorter than the Bragg wavelength. In wavelengths larger than the Bragg wavelength, the dispersion of the dielectric function can be ignored. The results achieved in this work are consistent with the experimental data [Wu, Q.; Hodgkinson, I.J.; Lakhtakia, A. Opt. Eng. 2000, 39, 1863]. A shift towards shorter wavelengths is observed for the Bragg peak with increasing void fraction, which is in agreement with the theoretical work of Lakhtakia [Microw. Opt. Technol. Lett. 2000, 24, 239]. Sorge et al. [Opt. Express 2006, 14, 10550] also found this effect in their experimental results on TiO₂ chiral thin films, while they also found that unlike our results the intensity of the reflectance of the Bragg peak decreases with increasing void fraction. This difference between our theoretical work and Sorge et al.'s experimental work can be related to the structural difference between the idealized theoretical model for chiral films and that obtained in experimental work. In the latter, as Sorge et al. have pointed out the experimental films exhibit a large amount of scattering due to the highly complex and non-ideal structure that the individual chiral elements exhibit.     

Field Electron Emission from Single‐Walled Carbon Nanotube Layers

Abstract

Field emission characteristics of single‐walled carbon nanotube layers have been investigated at room and low temperatures. For these layers the emission current density of 10 mA/cm² was obtained at the average field E _av = 1.6–3.8 V/µm. Current–voltage characteristics in Fowler–Nordheim coordinates have a break at emission current about 10^?8 A. Cooling of samples only insignificantly changed the form of current–voltage characteristics. This indicates, that investigated single‐walled nanotubes have the metal type conductivity.     

Influence of the magnetic self-field on the formation of a cathode plasma jet in steady-state vacuum arcs

It is shown that magnetic pinching of a cathode plasma jet is initiated after various microjets have merged to form a single jet at a distance r>10³ d from the cathode (d is the diameter of the cathode microspot). The plasma jet acquires the form of a paraboloid of revolution whose surface oscillates about the equilibrium position because of the inertia of the plasma transverse motion. At this point, cooling of the jet ceases. Pis’ma Zh. Tekh. Fiz. 23, 47–53 (June 12, 1997)     

Systematic hardness measurements on mixed and doped crystals of rubidium halides

Efforts are made to improve the hardness of rubidium halide crystals by (i) solid solution hardening and (ii) impurity hardening. Systematic microhardness measurements have been made on rubidium halide mixed crystals (RbBr-RbI and KI-RbI) and rubidium halide crystals doped with Sr²⁺ ions. The composition dependence of the hardness of mixed crystals follows the law ΔH _v =K x (1− x),where ΔH _v is the enhancement in hardness,K a constant andx and (1 −x) the concentrations of the first and second component of the mixed crystals, respectively. The hardness of doped crystals increases with the concentrationC of the dopant according to the law, ΔH _v+6 =k C ^m ,wherek andm are constants. The relative efficacy of the two methods of hardening is discussed.     

Supersolidity and the Thermodynamics of Solid Helium

The specific heat of solid helium in the temperature range below about 1.2 K has been found to contain a term varying as T ⁷, in addition to the usual T ³ contribution always found in a crystalline dielectric solid. It has been proposed by Anderson, Brinkman and Huse, (Science 310, 1164 (2005)) that the existence of this T ⁷ term supports their theory of supersolidity. However, in this paper we show that corrections to the phonon specific heat arising from phonon dispersion are much larger than expected based on simple order of magnitude estimates and, as a consequence, it is very unlikely that the existence of this T ⁷ term can be considered as evidence for supersolidity.      

On the effects of microstress on macroscopic diffusion processes

Summary The effects of internal microstress fields are neglected in a usual simulation of the diffusion of a small solute trough solid heterogeneous media. However, when a heterogeneous material is used in a structure undergoing external mechanical loading, highly nonuniform stress fields can arise locally due to the variable microstructure. In this paper a simple quasi-Fickian model is studied which employs a spatially variable stress-dependent diffusivity,D . The structure ofD stems from an assumption that the stresses nonuniformly open and close the pores of the material microstructure, thus providing preferential sites for accumulation of the diffusing solute. When =0, the usual stress-free Fickian diffusivity,D ⁰, is recovered. Because of the highly oscillatory stress fields on the micro level, when employing numerical methods, such as the finite element or finite difference method, the distance between discretization nodes must be far smaller than the microstructural oscillations to obtain accurate simulations. This fact makes direct numerical simulations involvingD virtually impossible without computationally intensive, and complicated, special techniques. In this paper upper bounds are developed for the difference between solutions produced when usingD and alternativelyD ⁰ in the body under analysis. The general case, whenD ⁰, and consequentlyD , are spatially variable, is considered. The bounds are a function of onlyD ⁰ and and do not require any knowledge of the stress-dependent solution, and can thus be used as an a-priori check to determine whether potentially expensive computations are necessary.Dedicated to Prof. Dr. Peter Haupt on the occasion of his 60th birthday     

Symmetric and non-symmetric periodic orbits for the digital filter map

We exhibit instances of non-symmetric periodic orbits for the digital filter map, resolving a question posed in the literature as to whether such orbits can exist. This piecewise irrational rotation, depending on a parameter a = 2cos θ, is an isometry of [?1, 1) × [?1, 1) and reflections in the two diagonals are time-reversing symmetries for the map. Symmetric orbits are plentiful and have been much investigated. Each periodic orbit is paired with a symbolic string, from the alphabet {?, 0, +}, arising under iteration of the map because of the presence of a line of discontinuity. We prove the existence of an infinite family of non-symmetric orbits where the period N starts at 29 and increases in steps of 5; they correspond to the strings (+00)⁵(+?)² 0 ^N?19. We describe several computer algorithms to find non-symmetric periodic orbits and their symbolic strings and list non-symmetric strings both for a = 0.5, and for N ≤ 100 across the parameter range. Our evidence suggests that non-symmetric orbits, though not plentiful, are characteristic of the dynamics of the map for all parameter values.     

Spectroscopic investigations of Cu2+ in Li2O-Na2O-B2O3-Bi2O3 glasses

Pure and copper doped glasses with composition,x Li ₂ O-(40-x)Na ₂ O-50B ₂ O ₃-10Bi ₂ O ₃,have been prepared over the range 0 ≤ x ≤ 40. The electron paramagnetic resonance (EPR) spectra of Cu²⁺ ions of these glasses have been recorded in the X-band at room temperature. Spin Hamiltonian parameters have been calculated. The molecular bonding coefficients, α² and β², have been calculated by recording the optical absorption spectra in the wavelength range 200–1200 nm. It has been observed that the site symmetry around Cu²⁺ ions is tetragonally distorted octahedral. The density and glass transition temperature variation with alkali content shows non-linear behaviour. The IR studies show that the glassy system contains BO₃ and BO₄ units in the disordered manner.     

From the studio to the snapshot: An immigrant photographer of the 1920s

Abstract

In his justly famous work, Looking at Photographs, John Szarkowski remarked¹ that ‘Photography has learned about its nature not only from the great masters, but also from the simple and radical works of photographers of modest aspiration and small renown ….’. It is thanks to critics like Szarkowski that we are encouraged to view photographs on their own terms, instead of always having to compare them to the rigid aesthetic hierarchies of Hochkunst.     

Surface Tension Maximum of Liquid 3He—Experimental Study

The surface tension of liquid ³He was measured as a function of temperature by means of the capillary rise method. Suzuki et al. [Europhysics Lett. 5, 333 (1988)] reported that the surface tension was almost temperature independent below 120 mK. Here we have examined it with greater precision and found that it has a small maximum around 100 mK. The surface tension increased with temperature from 35 mK and had a maximum of about 3×10^–4 as a fraction of the surface tension at 0 K. It was found that the surface tension maximum can be attributed mainly to the T⁴ ln T variation which has been theoretically derived by Misawa on the basis of a local approximation for the entropy including Fermi liquid effect.     

Propagation properties of partially coherent dark hollow beam in inhomogeneous atmospheric turbulence

Abstract

Propagation properties of a partially coherent dark hollow beam (PC-DHB) in inhomogeneous atmospheric turbulence are studied in detail. Analytical formulae for the root-mean-square (rms) spatial width, rms angular width, M²-factor of PC-DHB in inhomogeneous turbulence are derived based on the extended Huygens–Fresnel integral. It is found that PC-DHB spreads in inhomogeneous turbulence more rapidly than the free space, and the saturation propagation distances (SPDs) of relative spatial and angular spreadings for uplink slant paths with zenith angles of 45° or less are about 5 and 0.6 km, respectively. M²-factor of PC-DHB in turbulence depends on beam order, waist width, inner scale of the turbulence and the SPD of the normalized M²-factor for the propagation with zenith angles of 45° or less is about 30 km. Our results are useful for the free space optical communications and the beam propagation in the slant path.     

Thermodynamic Properties of He@C60

Abstract

Contributions to thermodynamic properties of the endohedral He@C₆₀, resulting from motion of He inside the cage, are calculated. The contribution to C _v shows a maximum at low temperatures. The maxima for ³He@C₆₀ and ⁴He@C₆₀ are at about 41 K and 30 K, respectively.     

Photoluminescence properties of β-SiAlON:Yb2+, a novel green-emitting phosphor for white light-emitting diodes

Abstract

We have synthesized Yb²⁺-activated Si_6?zAl_zO_zN_8?z (0.05z2.3, 0.03 mol% Yb²⁺0.7 mol%) green phosphors by solid-state reaction at 1900 °C for 2 h under a nitrogen pressure of 1.0 MPa. Phase purity, photoluminescence and its thermal quenching were investigated. A single phase was obtained for all values of z and Yb²⁺ concentration. A distinct emission band was observed at 540 nm originating from the 5d–4f electronic transition in Yb²⁺ under 480 nm excitation. The photoluminescence properties mainly depended on the Yb²⁺ concentration and chemical composition of the matrix. The resultant phosphor showed high thermal stability, that is, the emission intensity at 150 °C was about 82% of that measured at room temperature. The experimental results indicate that β-SiAlON:Yb²⁺ is a potential green phosphor for white light-emitting diodes (LEDs), which use blue LEDs as the primary light source.     

Cell attachment on diamond-like carbon coating

Preliminary results of diamond-like carbon (DLC) coating with its novel properties with no toxicity have caused a strong interest of commercial manufacturers of surgical implants. DLC coatings were prepared on polymethylmethacrylate (PMMA) at room temperature using ion beam assisted deposition (IBAD). It could be shown by X-ray photoelectron spectroscopy, Auger electron spectroscopy, and Raman spectroscopy that DLC coating prepared by 800 eV CHⁿ⁺ beam bombardment possessed a higher fraction ofsp ³ bonds in the structure of mixedsp ⁿ³ +sp ⁿ² bonding, resulting in a higher hydrophobicity. The results of the cell attachment tests indicated that DLC coatings exhibited low macrophage attachment and provided desirable surface for the normal cellular growth and morphology of the fibroblasts. At the same time, the number of both neutral granulocytes and platelets adhering to DLC coatings decreased significantly. These findings showed that DLC was a better coating with desirable tissue and blood compatibility.