14,836 research outputs found

    Impact-picture predictions for the γγ\gamma\gamma total cross section at LEP

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    We show that the rising total cross section σ(γγhadrons)\sigma(\gamma\gamma \to hadrons) recently observed by the L3 and OPAL Collaborations at LEP are fully consistent with the impact-picture for high-energy scattering. The impact picture is then used to predict this total cross section at higher energies. These experimental results confirm once more the success of the theoretical approach, which predicted for the first time, nearly thirty years ago, the universal increase of total cross sections at high energies.Comment: 5 pages, Latex, 1 figure. Revised versio

    Complete gradient-LC-ESI system on a chip for protein analysis

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    This paper presents the first fully integrated gradient-elution liquid chromatography-electrospray ionization (LC-ESI) system on a chip. This chip integrates a pair of high-pressure gradient pumps, a sample injection pump, a passive mixer, a packed separation column, and an ESI nozzle. We also present the successful on-chip separation of protein digests by reverse phase (RP)-LC coupled with on-line mass spectrometer (MS) analysis

    Misallocation and manufacturing TFP in China and India

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    Resource misallocation can lower aggregate total factor productivity (TFP).We use microdata on manufacturing establishments to quantify the potential extent of misallocation in China and India versus the United States. We measure sizable gaps in marginal products of labor and capital across plants within narrowly defined industries in China and India compared with the United States. When capital and labor are hypothetically reallocated to equalize marginal products to the extent observed in the United States, we calculate manufacturing TFP gains of 30%–50% in China and 40%–60% in India.India,China, Economy

    Misallocation and Manufacturing TFP in China and India

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    Resource misallocation can lower aggregate total factor productivity (TFP). We use micro data on manufacturing establishments to quantify the potential extent of misallocation in China and India compared to the U.S. Compared to the U.S., we measure sizable gaps in marginal products of labor and capital across plants within narrowly-defined industries in China and India. When capital and labor are hypothetically reallocated to equalize marginal products to the extent observed in the U.S., we calculate manufacturing TFP gains of 30-50% in China and 40-60% in India.

    Relative Prices and Relative Prosperity

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    The positive correlation between PPP investment rates and PPP income levels across countries is one of the most robust findings of the empirical growth literature. We show that this relationship is almost entirely driven by differences in the price of investment relative to output across countries. When measured at domestic prices rather than at international prices, investment rates are little correlated with PPP incomes. We find that the high relative price of investment in poor countries is solely due to the low price of consumption goods in poor countries. Investment prices are no higher in poor countries than in rich countries. These facts suggest that the low PPP investment rates in poor countries are not due to low savings rates or to high tax or tariff rates on investment. Poor countries instead appear to be plagued by low efficiency in producing investment goods and in producing exportables to trade for machinery and equipment.

    Successful islet allotransplantation in diabetic rats immunosuppressed with FK506: A functional and immunological study

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    The effect of a novel immunosuppressive agent, FK506, on fresh islet allografts was evaluated in diabetic rats across major histocompatibility complex (MHC) barriers with respect to the transplantation (TR) site, islet source, treatment regimen, and antidonor antibody (Ab) titers of the recipients after TR. The functional periods of Wistar (Wi) islets transplanted under kidney capsule (KC) or intraportally (IPo) and of a mixture of Wi and Lewis (Le) islets under KC or IPo in nonimmunosuppressed ACI rat recipients were 6.9 ± 0.4 (n = 7), 6.4 ± 0.5 (n = 7), 5.6 ± 0.4 (n = 7), and 6.2 ± 0.4 (n = 5) days, respectively. FK506 treatment at 1 mg/kg/d intramuscularly (IM) for 2 weeks (protocol I) following islet TR under KC and IPo significantly prolonged the allograft function to more than 71.8 ± 11.3 (n = 10) and 161.7 ± 18.6 (n = 11) days, respectively. Additional treatment with FK506 at 1 mg/kg/wk (protocol II) further increased the islet survival under KC to more than 212.6 ± 22.3 (n = 8) days. With this FK506 treatment protocol, the Wi + Le mixed-islet allograft function was extended to more than 106.1 ± 10.5 (n = 7) and 167.9 ± 28.6 (n = 7) days under KC and IPo, respectively. Nephrectomy in 8 8 ACI rats with long-term-functioning Wi (n = 6) and Wi + Le (n = 2) islet allografts resulted in their return to hyperglycemia. Immunohistochemical staining showed abundant insulin-positive cells at the graft site, with small numbers of CD4- and CD8-positive cells present in the vicinity of the normal-appearing islets. Macrophages were not detected. The immunosuppressive effect of FK506 was further tested in ACI rats presensitized by a previous Wi islet TR. When the duration between the first and second TR under KC was 114.3 ± 20.5 days, protocol II treatment significantly prolonged the graft function to more than 152.9 ± 28.7 (n = 8) days. However, with a short duration of about 2 weeks between the two TRs, the same FK506 protocol achieved islet graft function of 14.0 ± 3.8 days (n = 7). Additional immunosuppression with cyclophosphamide did not further improve the survival time. Antidonor Abs detected in ACI recipients of Wi islet allografts were significantly lower in the FK506-treated animals compared with the nontreatment group. Wi and Le skin grafts performed in three ACI rats with long-term-functioning Wi islets IPo caused the rejection of the islet allografts. Skin grafts were also rejected in the first-set fashion. Six ACI recipients with long-term-functioning IPo Wi islet allografts were rendered hyperglycemic by streptozocin (STZ) injection. Long-term normoglycemia without further FK506 immunosuppression was achieved following retransplantation with fresh Wi islets IPo (n = 2), but not under KC (n = 2). The results of the present study indicate that FK506 was an effective immunosuppressant for islet allotransplantation in diabetic ACI rats across MHC barriers with islets from two donor strains, as well as in sensitized recipients whose antidonor activities had subsided. The efficacy of the immunosuppression was influenced by the FK506 treatment protocol and the site of the islet transplant. The results suggest that FK506 could be useful in clinical islet TR. © 1994
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