1,374 research outputs found

    Lex Mercatoria in European and U.S. Trade Practice: Time to Take a Closer Look

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    This is an expanded version of the talk presented at the Fifth Annual Fulbright Symposium on International Legal Problems, Fourth Regional Meeting of the American Society of International Law, Current Developments in International Trade Cooperation and the Protection of the Environment and Human Rights, held on March 17, 1995, at Golden Gate University School of Law in San Francisco. Edited by Jeffrey A. Chen

    On Two Models of the Light Pulse Delay in a Saturable Absorber

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    A comparative analysis of two approaches to description of the light modulation pulse delay in a saturable absorber is presented. According to the simplest model, the delay of the optical pulse is a result of distortion of its shape due to absorption self-modulation in the nonlinear medium. The second model of the effect, proposed at the beginning of our century, connects the pulse delay with the so-called "slow light" resulting from the group velocity reduction under conditions of the coherent population oscillations. It is shown that all the known experimental data on the light pulse delay in saturable absorbers can be comprehensively described in the framework of the simplest model of saturable absorber and do not require invoking the effect of coherent population oscillations with spectral hole-burning and anomalous modifications of the light group velocity. It is concluded that the effect of group velocity reduction under conditions of coherent population oscillations has not received so far any experimental confirmation, and the assertions about real observation of the "slow light" based on this mechanism are groundless.Comment: Regretfully, the journal version of the paper (in Optics and Spectroscopy) appeared to be strongly corrupted due to ignorant editing. In particular, "coherent population oscillations" (CPO) was replaced by "population coherent oscillations" (PCO), "bleaching" - by "clearing", and "bleachable absorber " - by "clearable absorber". Here we present original version of the pape

    Liquidus Tracking: Controlled Rate Vitrification for the Cryopreservation of Larger Volumes and Tissues

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    BACKGROUND: Vitrification of cells or tissue at controlled cooling rates suitable for larger volumes, and with reduced cryoprotectant toxicity. OBJECTIVE: To set out the current understanding of the LiquidusTracking (LT) vitrification technique, and to discuss the challenges and benefits of translating the method into laboratory protocols more generally applicable to meet requirements of large volume and 3-D cryo-banking in the era of regenerative medicine. METHODS: By adding small amounts of cryoprotectants at each step and subsequently cooling the sample just above its freezing point before further increasing CPA concentration, cryoprotectant toxicity is minimized. RESULT: CPA toxicity can be reduced by lowering the temperature. Different manual approaches to LT were evaluated and further improved. CONCLUSIONS: Manual liquidus tracking is complicated and exhibits potential high variability. Nevertheless, this approach offers the possibility of testing several conditions simultaneously and could be used to pre-test conditions prior to automatic LT development

    Report on a collecting trip of the British Myriapod Group to Hungary in 1994

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    During a collecting trip participated jointly by the members of the British Myriapod Group and by Hungarian experts in 1994, 34 species of millipedes, 14 of centipedes, 8 of woodlice and 73 of spiders were recorded from Hungary. Two records of the millipede species Boreoiulus tenuis (Bigler, 1913) and Styrioiulus styricus (Verhoeff, 1896) were new to the fauna of Hungary

    Experimental and Computational Study of Area and Perimeter Contributions to Radiometer Forces

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    The relative contribution to the radiometric force of the area and perimeter of the vane is studied experimentally and numerically. Experimentally, a circular vane, a low-aspect rectangular vane, and a high-aspect rectangular vane were all tested on a force balance, with nano-Newton resolution, placed in a stagnant gas. The computational results were obtained through 2-D simulations using the direct simulation Monte Carlo method, as well as a discrete ordinate solution of the ES model kinetic equation. Gas pressure was varied from 0.006 to 6 Pa, which was a broad enough range to observe the characteristic peak force production of a radiometer in the transition regime, where the peak occurs at Kn ~ 0.1. It was found that the area of a radiometer vane is responsible for a significant amount ofthe total force production through a wide range of operating pressures. It is only at the highest background pressures, well after force production has peaked, that the vane perimeter appears to dominate the operation of the radiometer

    Decisional tool for cost of goods analysis of bioartificial liver devices for routine clinical use

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    BACKGROUND AIMS: Bioartificial liver devices (BALs) are categorized as advanced therapy medicinal products (ATMPs) with the potential to provide temporary liver support for liver failure patients. However, to meet commercial demands, next-generation BAL manufacturing processes need to be designed that are scalable and financially feasible. The authors describe the development and application of a process economics decisional tool to determine the cost of goods (COG) of alternative BAL process flowsheets across a range of industrial scales. METHODS: The decisional tool comprised an information database linked to a process economics engine, with equipment sizing, resource consumption, capital investment and COG calculations for the whole bioprocess, from cell expansion and encapsulation to fluidized bed bioreactor (FBB) culture to cryopreservation and cryorecovery. Four different flowsheet configurations were evaluated across demands, with cell factories or microcarriers in suspension culture for the cell expansion step and single-use or stainless steel technology for the FBB culture step. RESULTS: The tool outputs demonstrated that the lowest COG was achieved with microcarriers and stainless steel technology independent of the annual demand (1500-30 000 BALs/year). The analysis identified the key cost drivers were parameters impacting the medium volume and cost. CONCLUSIONS: The tool outputs can be used to identify cost-effective and scalable bioprocesses early in the development process and minimize the risk of failing to meet commercial demands due to technology choices. The tool predictions serve as a useful benchmark for manufacturing ATMPs

    Applications and optimization of cryopreservation technologies to cellular therapeutics

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    Delivery of cell therapies often requires the ability to hold products in readiness whilst logistical, regulatory and potency considerations are dealt with and recorded. This requires reversibly stopping biological time, a process which is often achieved by cryopreservation. However, cryopreservation itself poses many biological and biophysical challenges to living cells that need to be understood in order to apply the low temperature technologies to their best advantage. This review sets out the history of applied cryopreservation, our current understanding of the various processes involved in storage at cryogenic temperatures, and challenges for robust and reliable uses of cryopreservation within the cell therapy arena

    Utilisation of chimeric lyssaviruses to assess vaccine protection against highly divergent lyssaviruses

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    Lyssaviruses constitute a diverse range of viruses with the ability to cause fatal encephalitis known as rabies. Existing human rabies vaccines and post exposure prophylaxes (PEP) are based on inactivated preparations of, and neutralising antibody preparations directed against, classical rabies viruses, respectively. Whilst these prophylaxes are highly efficient at neutralising and preventing a productive infection with rabies virus, their ability to neutralise other lyssaviruses is thought to be limited. The remaining 15 virus species within the lyssavirus genus have been divided into at least three phylogroups that generally predict vaccine protection. Existing rabies vaccines afford protection against phylogroup I viruses but offer little to no protection against phylogroup II and III viruses. As such, work involving sharps with phylogroup II and III must be considered of high risk as no PEP is thought to have any effect on the prevention of a productive infection with these lyssaviruses. Whilst rabies virus itself has been characterised in a number of different animal models, data on the remaining lyssaviruses are scarce. As the lyssavirus glycoprotein is considered to be the sole target of neutralising antibodies we generated a vaccine strain of rabies using reverse genetics expressing highly divergent glycoproteins of West Caucasian Bat lyssavirus and Ikoma lyssavirus. Using these recombinants, we propose that recombinant vaccine strain derived lyssaviruses containing heterologous glycoproteins may be a suitable surrogate for wildtype viruses when assessing vaccine protection for the lyssaviruses
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