Lithology and palynology of cave floor sediment cores from Wakulla Spring, Wakulla County, Florida

Five short bottom sediment cores taken in Wakulla Spring Wakulla County, Florida, were described lithologically and sampled for palynological study. Four of the cores were recoveredfrom sediments at the spring cave entrance (130 feet water depth). One core was taken in a fossil vertebrate bone bed, 280 feet distance into the main spring cave at a water depth of 240 feet. Sediments in the cores are composed of alternating intervals of quartz sand and calcilitite, containing freshwater diatoms, freshwater mollusk shells and plant remains. The predominant pollen present in all cores consists of a periporate variety typical of the herb families Chenopodiaceae and Amaranthaceae. Arboreal flora, typical of the area surrounding the spring today, represent a very low percentage of thle pollen assemblage in the cores. Clustered Chenopod-Amaranth type pollen observed in one core suggest minimal transport prior to deposition, and indicate that the bottom sediments in the cave may be essentially In situ. An absence of exotic flora suggests a Quaternary age for the sediments. (PDF contains 11 pages.

Study of high temperature bearing materials

Experimental investigation identifies materials suitable for use in potassium lubricated turbo-generator journal bearing and shaft applications at high temperatures. Attention is given to nonrefractory metals and alloys, refractory metals and alloys, Fe-Ni-Co bonded carbides, refractory compounds, and refractory metal bonded carbides

Collective states from random interactions

The anharmonic vibrator and rotor regions in nuclei are investigated in the framework of the interacting boson model using an ensemble of random one- and two-body interactions. Despite the randomness of the interactions (in sign and size) we find a predominance of L(P)=0(+) ground states and strong evidence for the occurrence of both vibrational and rotational band structure.Comment: 4 pages, 2 figures, 1 tables, to be published in the proceedings of Bologna 200

Randomly interacting bosons, mean-fields and L=0 ground states

Random interactions are used to investigate to what extent the low-lying behavior of even-even nuclei depend on particular nucleon-nucleon interactions. The surprising results that were obtained for the interacting boson model, i.e. the dominance of ground states with L=0 and the occurrence of both vibrational and rotational structure, are interpreted and explained in terms of a mean-field analysis.Comment: 6 pages, 2 figures, Invited talk at NP2001, Goettingen, March 2001, World Scientific (2001), in pres

The Output Contributions of Computer Equipment and Personnel: A Firm- Level Analysis

This paper examines the output contributions of capital and labor deployed in information systems (IS) at the firm level during the period 1988-91 throughout the business sector, using two different sources of data on these inputs. Our production function estimates suggest that there are substantial excess returns to both IS capital and IS labor, although the size and significance of the excess returns to IS capital is larger. Computer capital and labor jointly contribute, or account for, about 21 percent of output, although only about 10% of both capital and labor income accrue to IS factors. Although IS employees accounted for a very small share of total employment by 1986, IS employment growth is estimated to have made a larger contribution to 1976-86 output growth than non-IS employment, due to the very rapid growth (16% per annum) of IS employment. The estimated marginal rate of substitution (MRS) between IS and non-IS employees, evaluated at the sample mean, is 6: one IS employee can be substituted for six non-IS employees without affecting output.

Private Investment in R&D to Signal Ability to Perform Government Contracts

Official government statistics on the "mission-distribution" of U.S. R&D investment are based on the assumption that only the government sponsors military R&D. In this paper we advance and test the alternative hypothesis, that a significant share of privately-financed industrial R&D is military in orientation. We argue that in addition to (prior to) contracting with firms to perform military R&D, the government deliberately encourages firms to sponsor defense research at their own expense, to enable the government to identify the firms most capable of performing certain government contracts, particularly those for major weapons systems. To test the hypothesis of, and estimate the quantity of, private investment in 'signaling' R&D, we estimate variants of a model of company R&D expenditure on longitudinal, firm-level data, including detailed data on federal contracts. Our estimates imply that about 30 percent of U.S. private industrial R&D expenditure in 1984 was procurement- (largely defense-) related, and that almost half of the increase in private R&D between 1979 and 1984 was stimulated by the increase in Federal demand.

Universal Secure Error-Correcting Schemes for Network Coding

This paper considers the problem of securing a linear network coding system against an adversary that is both an eavesdropper and a jammer. The network is assumed to transport n packets from source to each receiver, and the adversary is allowed to eavesdrop on \mu arbitrarily chosen links and also to inject up to t erroneous packets into the network. The goal of the system is to achieve zero-error communication that is information-theoretically secure from the adversary. Moreover, this goal must be attained in a universal fashion, i.e., regardless of the network topology or the underlying network code. An upper bound on the achievable rate under these requirements is shown to be n-\mu-2t packets per transmission. A scheme is proposed that can achieve this maximum rate, for any n and any field size q, provided the packet length m is at least n symbols. The scheme is based on rank-metric codes and admits low-complexity encoding and decoding. In addition, the scheme is shown to be optimal in the sense that the required packet length is the smallest possible among all universal schemes that achieve the maximum rate.Comment: 5 pages, submitted to IEEE ISIT 201

Level repulsion in hybrid photonic-plasmonic microresonators for enhanced biodetection

We theoretically analyse photonic-plasmonic coupling between a high Q whispering gallery mode (WGM) resonator and a core-shell nanoparticle. Blue and red shifts of WGM resonances are shown to arise from crossing of the photonic and plasmonic modes. Level repulsion in the hybrid system is further seen to enable sensitivity enhancements in WGM sensors: maximal when the two resonators are detuned by half the plasmon linewidth. Approximate bounds are given to quantify possible enhancements. Criteria for reactive vs. resistive coupling are also established

The Effect of Pharmaceutical Innovation on the Functional Limitations of Elderly Americans Evidence from the 2004 National Nursing Home Survey

I examine the effect of pharmaceutical innovation on the functional status of nursing home residents using cross-sectional, patient-level data from the 2004 National Nursing Home Survey. This was the first public-use survey of nursing homes that contains detailed information about medication use, and it contains better data on functional status than previous surveys. Residents using newer medications and a higher proportion of priority-review medications were more able to perform all five activities of daily living (ADLs), controlling for age, sex, race, marital status, veteran status, where the resident lived prior to admission, primary diagnosis at the time of admission, up to 16 diagnoses at the time of the interview, sources of payment, and facility fixed effects. The ability of nursing home residents to perform activities of daily living is positively related to the number of “new” (post-1990) medications they consume, but unrelated to the number of old medications they consume. If 2004 nursing home residents had used only old medications, the fraction of residents with all five ADL dependencies would have been 58%, instead of 50%. During the period 1990-2004, pharmaceutical innovation reduced the functional limitations of nursing home residents by between 1.2% and 2.1% per year.