Buzz: Face-to-Face Contact and the Urban Economy

This paper argues that existing models of urban concentrations are incomplete unless grounded in the most fundamental aspect of proximity; face-to-face contact. Face-to-face contact has four main features; it is an efficient communication technology; it can help solve incentive problems; it can facilitate socialization and learning; and it provides psychological motivation. We discuss each of these features in turn, and develop formal economic models of two of them. Face-to-face is particularly important in environments where information is imperfect, rapidly changing, and not easily codified, key features of many creative activities.Agglomeration, clustering, urban economics, face-to-face

Excavations at Tas-Silg, Malta : a preliminary report on the 1996-1998 campaigns conducted by the Department of Classics and Archaeology of the University of Malta

The area known as Tas-Silg is situated in the south-eastern part of the island of Malta, close to Marsaxlokk harbour. In reality the place name refers to the small church dedicated to Our Lady of the Snows (hence Tas-Silg) situated at the point where the narrow · road from Zejtun forks out in two directions: to Delimara and Xrobb il-Ghagin due south-east and to Marsaxlokk village due south-west. A British-period fort occupying the highest point of the elongated hill further south along· the first road also carries the same place name. The lower and more compact hill on which the excavations have been conducted is called 'Ta' Berikka' , but since it is so close to the above-mentioned church (only 50 m to the north) the tradition of calling it Tas-Silg is now well established and there is no sense in changing it. The site has a commanding view of the Marsaxlokk harbour to the south and overlooks two other bays, Marsascala and St Thomas's bay, to the north-east. On all sides the slope is broken up by man-made terraced fields There is no doubt that the topography of the site must have been a determining factor in its choice for the establishment of a religious centre in the Temple period of Maltese pehistory (3000--2500 BC), though one must keep in mind that close to Tas-Silg there are three other prehistoric temple sites. each one with a completely different topography. The Temple people were quite introverted in their cultural isolation and do not seem to have been much interested in seafaring and in the outside world. The situation changed radically in the following age, the Bronze Age. when the island was occupied by people who set up villages on naturally defensible hilltops, occasionally fortifying them with artificial ramparts. The Tas-Silg hill with its temple ruins was occupied by these people, but it is not as yet clear for what purpose. The scenario changed again in historical times when the central and western Mediterranean started to be parcelled out among the commercial powers originating in the eastern Mediterranean. The Greeks do not seem to have even tried 10 colonize Malta as they did in neighbouring Sicily. The Phoenicians, however, did occupy the island, apparently through a slow process of peaceful penetration and eventual political and cultural assimi lation. It was in this period that the ruins of the megalithic temple were transformed into a Phoenician extraurban shrine dedicated to Astarte, which in time expanded into a full y-fledged sanctuary with an international reputation. The last chapter in the millennia- long history of the site was written when the colonnaded courtyard in front of the old temple was transformed into an early Christian church. Any use made of the site in the following Arab period is, once again, poorly understood.peer-reviewe

AN ANALYSIS OF NUTRIENT INTAKE FOR SELECTED FAMILIES IN FLORIDA'S EXPANDED NUTRITION PROGRAM

Food Consumption/Nutrition/Food Safety,

Environmental and fishing effects on the dynamic of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia)

This analysis of the variations of brown tiger prawn (Penaeus esculentus) catch in the Moreton Bay multispecies trawl fishery estimated catchability using a delay difference model. It integrated several factors responsible for variations in catchability: targeting of fishing effort, increasing fishing power and changing availability. An analysis of covariance was used to define fishing events targeted at brown tiger prawns. A general linear model estimated inter-annual variations of fishing power. Temperature induced changes in prawn behaviour played an important role in the dynamic of this fishery. Maximum likelihood estimates of targeted catchability ($3.92 \pm 0.40 \ 10^{-4}$ boat-days$^{-1}$) were twice as large as non-targeted catchability ($1.91 \pm 0.24 \ 10^{-4}$ boat-days$^{-1}$). The causes of recent decline in fishing effort in this fishery were discussed.Comment: revised manuscript following reviewers comments + adding data and code for reader

Ecohydrological Controls on Grass and Shrub Above-ground Net Primary Productivity in a Seasonally Dry Climate

Seasonally dry, water‐limited regions are often co‐dominated by distinct herbaceous and woody plant communities with contrasting ecohydrological properties. We investigated the shape of the above‐ground net primary productivity (ANPP) response to annual precipitation (Pa) for adjacent grassland and shrubland ecosystems in Southern California, with the goal of understanding the role of these ecohydrological properties on ecosystem function. Our synthesis of observations and modelling demonstrates grassland and shrubland exhibit distinct ANPP‐Pa responses that correspond with characteristics of the long‐term Pa distribution and mean water balance fluxes. For annual grassland, no ANPP occurs below a ‘precipitation compensation point,’ where bare soil evaporation dominates the water balance, and ANPP saturates above the Pawhere deep percolation and runoff contribute to the modelled water balance. For shrubs, ANPP increases at a lower and relatively constant rate across the Pa gradient, while deep percolation and runoff account for a smaller fraction of the modelled water balance. We identify precipitation seasonality, root depth, and water stress sensitivity as the main ecosystem properties controlling these responses. Observed ANPP‐Paresponses correspond to notably different patterns of rain‐use efficiency (RUE). Grass RUE exceeds shrub RUE over a wide range of typical Pa values, whereas grasses and shrubs achieve a similar RUE in particularly dry or wet years. Inter‐annual precipitation variability, and the concomitant effect on ANPP, plays a critical role in maintaining the balance of grass and shrub cover and ecosystem‐scale productivity across this landscape

2-aminophenols containing electron-withdrawing groups from N-aryl hydroxylamines

Reaction of substituted N-aryl hydroxylamines with methanesulfonyl chloride, p-toluenesulfonyl chloride, or trifluoromethanesulfonic anhydride under basic conditions leads to the rearranged 2-aminophenols (45-94%). The overall reaction sequence can be performed using polymer-supported sulfonyl chloride resin allowing for the effective conversion of N-aryl hydroxylamines to the 2-aminophenols without the need for chromatography

Laser anemometer measurements in a transonic axial-flow fan rotor

Laser anemometer surveys were made of the 3-D flow field in NASA rotor 67, a low aspect ratio transonic axial-flow fan rotor. The test rotor has a tip relative Mach number of 1.38. The flowfield was surveyed at design speed at near peak efficiency and near stall operating conditions. Data is presented in the form of relative Mach number and relative flow angle distributions on surfaces of revolution at nine spanwise locations evenly spaced from hub to tip. At each spanwise location, data was acquired upstream, within, and downstream of the rotor. Aerodynamic performance measurements and detailed rotor blade and annulus geometry are also presented so that the experimental results can be used as a test case for 3-D turbomachinery flow analysis codes

Enantioselective Total Synthesis of (–)-Myrifabral A and B

A catalytic enantioselective approach to the Myrioneuron alkaloids (−)-myrifabral A and (−)-myrifabral B is described. The synthesis was enabled by a palladium-catalyzed enantioselective allylic alkylation, that generates the C(10) all-carbon quaternary center. A key N-acyl iminium ion cyclization forged the cyclohexane fused tricyclic core, while vinyl boronate cross metathesis and oxidation afforded the lactol ring of (−)-myrifabral A. Adaptation of previously reported conditions allowed for the conversion of (−)-myrifabral A to (−)-myrifabral B