Complex anterior chamber dysgenesis with bilateral corneal ectasia

BACKGROUND: Sclerocornea is a congenital, uni- or bilateral, non-progressive, non-inflammatory malformation characterized by histological changes of the cornea resembling scleral tissue. CASE REPORT: We report the case of a 2-month-old child with bilateral dysplasia of the anterior segment including: 1. extreme corneal ectasia; 2. vascularized, opacified microcornea; 3. presence of rudimental limbus; 4. anterior scleral dysplasia. The axial length measured by means of ultrasonography (A-scan) was about 24 mm in both eyes. A penetrating keratoplasty was first performed in the right eye and one week later in the left eye. Intraoperatively an advanced iris atrophy with extensive anterior synechiae, as well as a localized anterior subcapsular cataract were seen bilaterally. A pale optic disk with a maximally enlarged optic cup could be seen only in the left eye. CONCLUSION: Although the histologic examination was compatible with the diagnosis of sclerocornea, the presence of atypical clinical findings previously unreported does not allow a definite classification of the case reported herein.     

Temperatures in linguistics as a model of thermodynamics

Natural languages have been taken as models of systems with strong statistical correlations. In such systems the usual probabilistic limiting laws (Gauss etc.) are no more valid and the concept of higher order temperatures can be applied. It has been shown that this is the case in such languages as English, German, French, Russian and Japanese, for letter and word statistics. The corresponding temperatures (up to the 5-th order), entropies and statistical moments have been calculated and their mutual relations have been checked.... erst wenn du plötzlich Fänger wirst des Balles, den eine ewige Mitspielerin dir zuwarf, ... erst dann ist Fangen-können ein Vermögen, nicht deines, einer Welt.(... only when you suddenly catch the ball which the eternal fellow player throws to you,... only then the catching ability is an accomplishment, not of you, but of the world.)R. M. Rilke (from the motto of [3])Supported by Committee of Scientific Research, Warsaw (KBN), Project Nr. 20412 91 01.     

The effects of pick density on order picking areas with narrow aisles

The cost and service performance of an order fulfillment center are determined partly by how workers are organized into an order picking system. One common approach is batch picking, in which workers circumnavigate a picking area with other workers, gathering items on a pick list. In some systems with high space utilization, narrow aisles prohibit workers from passing one another when in the same aisle, and this leads to congestion. We build analytical and simulation models of these systems to investigate their behavior under different levels of activity. Among other things, our results suggest that when the system is busier and pick density is high (that is, when workers stop often to make picks) congestion is less of a problem and workers are more productive.     

Tricalcium aluminate hydration: Microstructural observations by in-situ electron microscopy

Environmental scanning electron microscopy (ESEM) was used to study the microstructural changes that take place during the hydration of tricalcium aluminate (C₃A) in the absence and presence of gypsum (CS¯H₂; where A = Al₂O₃, C = CaO, H = H₂O, S¯ = SO₃). The ESEM proves to be a valuable tool in the observation of cement hydration and no specialised equipment other than the ESEM is required. The hydration process can be observed at any time without the need to halt the hydration process prior to specimen preparation. Subsequently, artefacts associated with specimen preparation, such as water loss and desiccation, are now avoided. In the absence of sulphate, amorphous gel, poorly crystalline hexagonal calcium aluminate hydrate (? C₄AH₁₉) and cubic calcium aluminate hydrate (C₃AH₆) are observed on the surface of C₃A grains. When small amounts of sulphate (2% gypsum) are present the same phases are observed. If larger amounts of sulphate (25% gypsum) are added to the system amorphous gel products, crystalline ettringite (C₆AS¯₃H₃₂) and monosulphate (C₄AS¯H₁₂) are observed. The crystalline products grow both within the amorphous gel and, where space allows, in interstices suggesting a through solution mechanism of transport.     

Imagining culture and the city in planning history: some reflections on the public and private

Geography, planning and policy making. P. T. Kivell and J. T. Coppock (eds), GeoBooks, Norwich, 1986. 310 pp, £25.00 $41.25, ISBN 0 86094 211 2

Counterurbanization. International case studies of socio‐economic change in the rural areas. Ronald Perry, Ken Dean and Bryan Brown, GeoBooks, Norwich, 1986. 280 pp, £25.00 $41.25, ISBN 0 86094 205 8

The twentieth century American city: problem, promise, and reality. Jon C. Teaford, Johns Hopkins University Press, Baltimore, 1986. 192 pp, $20.00 cloth ISBN 0 8018 3094 X $8.95 paper ISBN 0 8018 3096 6

San Francisco, 1865–1932: politics, power and urban development. William Issel and Robert W. Cherny, University of California Press, Berkeley, 1986. 294 pp, $35.00, ISBN 0 520 05263 3

The limits of power: great fires and the process of city growth in America. Christine Meisner Rosen, University Press, Cambridge, 1986. 395 pp, £30.00, $39.50, ISBN 0 521 30319 2

Critical issues in urban economic development. Volumes I and II. Victor A. Hausner (ed.), Clarendon Press, Oxford, 1986–7. 235 pp and 207 pp, £22.50 each, ISBN 0 19 823226 7 and ISBN 0 19 823268 3

The elusive city; five centuries of design, ambition and miscalculation. Jonathan Barnett, Harper and Row, New York, 1986. 210 pp, $23.50, ISBN 0 06 430377 2

The conservation of ecosystems and species. Gareth E. Jones, Croom Helm, London, 1987. 277 pp, £27.50, ISBN 0 7099 1463 6

Medicine and industrial society. A history of hospital development in Manchester and its region, 1752–1946. John V. Pickstone, University Press, Manchester, 1985. 369 pp, £35.00, ISBN 0 7190 1809 9

The paradox of professionalism: reform and public service in urban America, 1900–1940. Don S. Kirschner, Greenwood Press, Westport, Conn., Contributions in American History, 119, 1986. 195 pp, $32.95, ISBN 0 313 25345 5

An organisational approach to regional planning. Mario Rui Martins, Gower, Aldershot, 1986. 244 pp, £18.50 ISBN 0 566 00515 8

The tenant movement in New York City, 1904–1984. Ronald Lawson (ed.), Rutgers University Press, New Brunswick, New Jersey, 1986 289 pp, $35.00 cloth $15.00 paper, ISBN 0 8135 1158 5

The Scottish thirties. An architectural introduction. Charles McKean, Scottish Academic Press, Edinburgh, 1987. 200 pp, £17.50 hb ISBN 0 7073 0493 8, £8.50 pb ISBN 0 7073 0493 6

Hikaku Toshi Keikaku Josetsu (Introduction to comparative urban planning; land use controls in Britain and the US). Shun‐ichi Watanabe, Sanseido, Tokyo, 1985. 304 pp, ¥3600, ISBN 4 385 30895 0

Arabic‐Islamic cities. Building and planning principles. Besim Selim Hakim, KPI, London, 1986. 192 pp, £35.00, ISBN 0 7103 0094 8

Imagining tomorrow: history, technology, and the American future. Joseph J. Corn (ed.), MIT Press, Cambridge, Massachusetts, 1986. 237 pp, $17.50 cloth, ISBN 0 262 03115 9     

Percolation current in organic semiconductors

The charge transport in organic semiconductors has been investigated theoritically. A n analytical model describing the hopping current is developed. This model is based on VRH (variable range hopping) theory and percolation theory. The results of calculation are compared to the prediction of Mott’s formalism, which has been widely used to describe hopping transport in amorphous semiconductors. The model is also found to be in good agreement with recent experimental data.     

A reexamination of the distance-based facility layout problem

In this paper we qualitatively and numerically compare basic modeling approaches to the distance-based facility layout problem and the types of result obtained from them. In the process we observe that when the facility layout problem is modeled as a QAP, one will not necessarily obtain an optimal solution to the layout problem even if the QAP is solved to optimality. We also propose an alternative distance measure, namely, EDIST, which is based on the expected distance between two departments. We illustrate how the EDIST measure addresses some of the well-known shortcomings associated with the centroid-to-centroid distance measure.     

Specific recognition and formation of two- dimensional streptavidin domains in monolayers: applications to molecular devices

By virtue of the high-affinity specific interaction between the vitamin, biotin, and the protein, streptavidin, monolayers of synthetic lipids with biotin headgroups can tightly bind streptavidin at the lipid-water interface. Through this specific recognition fluorescently-labelled streptavidin spontaneously organizes in the plane of the interface to form large protein domains, directly visible in situ by fluorescence microscopy and exhibiting optical anisotropy. Further structural characterization has shown that these domains are two-dimensional protein crystals. Correlation with the known three-dimensional crystal structure of streptavidin indicates that two of streptavidin's four biotin binding sites are free for further derivatization to create multilayered organized protein molecular devices.     

Flow through a convergence. Part 1: Critical conditions for unstable flow

The critical conditions leading to fracture in elongation and different types of flow instabilities were examined in uniaxial elongation and in a capillary rheometer equipped with dies having different entry profiles. Either ductile or brittle fracture may be observed, ductile being related to necking of material. The critical stress approach was used to predict fracture in elongation. All linear polymers studied in this work exhibited ductile fracture in uniaxial elongation, but the transition to brittle fracture is discussed in relation to existing experiments with other materials. In a ductile fracture regime, critical stress and work both increase with an increasing rate of deformation, whereas in a brittle regime the critical values remain constant. The converging flow studies indicated that two types of flow instability that have been previously related to each other, namely, pressure oscillations and voltions distortions, are of different origins. The critical flow rate for pressure oscillations is independent of entry profile, and the origin for this type of instability lies along the wall of the capillary. On the other hand, the critical flow rate for volume distortions increased with a decreasing entry angle, indicating that volume distortions are not a consequence of pressure oscillation, nor are their origin at the capillary wall. Numerical simulations were used to determine the stress profiles within the flow, and it was shown that the onset of volume distortions is directly related to the magnitude of elongational stress and work, and may therefore be considered to be caused by fracture in elongation. In dies with 90° entry profile, volume distortions were observed simultaneously with pressure oscillations, making it difficult to distinguish between the two phenomena.