This paper presents an analysis of a public assistance program for small–scale entrepreneurship in peripheral areas. Public assistance compensates for market inefficiencies where the decision rules of financial institutions discriminate against otherwise viable small firms in capital markets. Lending institutions perceive high risk in providing debt capital when little information is present. Using empirical data from Israel, the determinants of this risk are estimated and the role of location in creating this information asymmetry is stressed. These results empirically establish that (1) location matters in determining the risk profile of the firm, (2) locationally targeted programs can reduce the information asymmetries that make peripheral firms unattractive to lenders, and (3) these programs can also generate positive welfare effects. Finally, there is speculation on the potential role of ICT (information and communications technology) in increasing the visibility of small firms in remote locations and creating a more symmetrical flow of information.
Implementing a logic machine on a single molecule was recently discussed with experimental roadmarks. Lasers were used to control the input and sometimes also the output of information with additional processing done via inter- and intramolecular dynamics. We examine the special requirements for an experiment that mimics a logic circuit. We use two-photon processes as physical examples of our considerations and discuss both combinational and sequential logic machines.
Inherited diseases are associated with profound phenotypic variability, which is affected strongly by genetic modifiers. The splicing machinery could be one such modifying system, through a mechanism involving splicing motifs and their interaction with a complex repertoire of splicing factors. Mutations in splicing motifs and changes in levels of splicing factors can result in different splicing patterns. Changes in the level of normal transcripts or in the relative pattern of different mRNA isoforms affect disease expression, leading to phenotypic variability. Here, we discuss the splicing machinery in terms of its significance in disease severity and its potential role as a genetic modifier.
HHeF, a chemically-bound helium compound, has been predicted to be metastable in the gas phase. It decays by tunneling through energy barriers in picosecond timescales into He+HF and H+He+F. This paper studies the stability of HHeF in pressurized solid helium. Using realistic potentials for the HHeF/He interaction, the potential energy along the minimum energy paths for decomposition is evaluated, and tunneling decay times are computed by the WKB approximation. It is found that for pressures above 500 MPa, decomposition into H+He+F is completely suppressed. At 23 GPa, the highest pressure studied, the timescale for HHeF–>He+HF is in the millisecond range. At pressures well above 23 GPa, HHeF is thus expected to remain stable indefinitely. (C) 2002 American Institute of Physics.
A therapeutic, cosmetic or cosmeceutic compn. for topical application, capable of stabilizing an active ingredient and delivering the active ingredient, comprises a plurality of microcapsules having a core-shell structure. The microcapsules have a diam. of approx. 0.1 to 100 μ. The core of each microcapsule includes at least one active ingredient and is encapsulated within a microcapsular shell. The shell is comprised of at least one inorg. polymer obtained by a sol-gel process, and the shell protects the active ingredient before topical application and is designed to release the active ingredient from the microcapsules following application. The compn. is useful in encapsulating active ingredients, such as benzoyl peroxide, that are unstable in other formulation, or are irritating to the skin. Me salicylate were mixed with tetraethoxysilane (TEOS). The org. phase was emulsified in an aq. soln. contg. 1% cetyltrimethyl ammonium chloride (CTAC) under high shear. This emulsion was then poured into a reactor contg. aq. NaOH soln. at pH 11.5. The soln. was stirred and after 7 days the product was pptd. in a centrifuge. The final product was re-suspended in water contg. 1% polyvinylpyrrolidone to receive a suspension contg. 32.4% Me salicylate encapsulated in silica particles of 0.5-10 μ. [on SciFinder(R)]
This paper presents a three-dimensional biomechanical model of the canine hind limb, and describes the process of determining the muscle forces and joint reaction forces and moments occurring in the hind limb during three-legged stance. The model was based on anatomical and morphometric data presented in a previous paper. Equations of equilibrium were formulated for the different components of the hind limb. Since the number of unknowns exceeded the number of equations, the problem was statically indeterminate.
Two optimization techniques were applied to solve this statically indeterminate problem. The resultant hip-joint reaction force (acting on the acetabulum) predicted by these optimization methods ranged between 0.73 and 1.04 times body weight, and was directed dorsally, medially and caudally. The resultant knee-joint reaction force (acting on the femur) ranged between 1.05 and 1.08 times body weight and was directed dorsally, laterally and cranially. The largest muscle forces predicted by the minimization of maximal muscle stress (MMMS) criterion were in the biceps femoris (0.24 times body weight), rectus femoris (0.15 time body weight), medial gluteal (0.18 times body weight), semi-membranous (0.09 times body weight), the lateral and intermediate vastus (0.18 times body weight) and the medial vastus (0.17 times body weight). The largest muscle forces predicted by the minimization of the sum of muscle forces (MSMF) criterion were in the biceps femoris (0.29 times body weight), lateral and intermediate vastus (0.45 times body weight), and the deep gluteal (0.16 times body weight).
The magnitudes and directions of the forces in the joints of the canine hind limb, as well as in the muscles that surround these joints, provide a database needed for future biomechanical analyses of the physiology and pathophysiology of the canine hind limb. (C) 2002 Elsevier Science Ltd. All rights reserved.
Pulsed electromagnetic fields (PEMFs) have been found to be beneficial to a wide variety of biological phenomena. In particular, PEMFs have been shown to be useful in the promotion of healing of ununited fractures. Conflicting information exists regarding the benefit of using PEMFs to accelerate the healing of fresh fractures. This paper reports on the evaluation of the effect of a new PEMF generator (PAP IMI(R)) on the healing of fresh ulnar fractures in rats. This device is unique by virtue of the extremely high power output of each of the pulses it generates. Ulnar fractures were created in rats by using a bone cutter, thus producing a 2-3 mm bone defect. Rats were then randomly divided into treatment and control groups. The treatment group underwent periodic treatments with the PAP IMI(R), and the control group received no treatment. Radiographs of rats from both groups were taken at 1-week intervals. Histological evaluation was performed at the end of the study. Radiographic and histopathological evaluations were scored, and scores were used to assess both rate and quality of healing. The radiographic results demonstrated gradual bridging callus formation in both control and treatment groups, however, the healing process was faster in rats that were not treated by PEMF. Histological evaluation demonstrated that the fibrous content of the callus in rats belonging to the treatment group was significantly higher than that in rats belonging to the control group. The results of this study do not support the claim that PEMF generated by the PAP-IMI(R) stimulate osteogenesis and bone healing after the creation of fresh ulnar fractures in rats.
Ultrafast spin-flip is used to monitor the subpicosecond intersystem crossing dynamics from the (1)Pi to the (3)Pi state following photodissociation of ClF isolated in an Ar matrix by means of pump-probe spectroscopy. After photoexcitation of the (1)Pi state analysis of the populations of triplet states shows that about 50 percent of the spin-flip occurs during the first bond stretch which takes about 250 fs. The early time dynamics of the Cl-F bond in an Ar matrix is investigated theoretically by selecting representative singlet and triplet excited states from a diatomics-in-molecules Hamiltonian. In a one-dimensional model, wave-packet simulations for the first excursion are performed which give a lower limit of about 60 fs for the spin-flip process. The ultrafast spin flip is supported by the caging of the wave packet by the neighboring Ar atoms. Already before collision of the F and Ar atoms the rather large energy gap between the (1)Pi and (3)Pi states in the Franck-Condon region is reduced rapidly to near degeneracy. As a consequence the spin-orbit interaction becomes dominant, inducing more than 40% admixture of the triplet character in the (1)Pi state. Subsequent kinetic energy transfer from ClF to Ar, not yet included in the model, should slow down the Cl and F atoms on their way back toward shorter bond distances, implying stabilization of the wave packet in the (3)Pi state, where it is monitored by the probe laser pulse.
The present invention generally relates to safe and stable sunscreen compns. comprising of at least one sunscreen active ingredient in the form of an inert sol-gel microcapsules encapsulating UV absorbing compds. in any acceptable cosmetic vehicle. The compn. according to the present invention can comprise several UV absorbers that may be encapsulated in the same sol-gel microcapsule or in different capsules. The hydrophobicity/hydrophilicity character of the sol-gel microcapsules can be controlled by selecting suitable sol-gel precursors and suitable reaction conditions and can be chosen to be compatible with the cosmetic vehicle to be used in the sunscreen compn., thus, the present invention facilitates an easy incorporation of the composite sol-gel encapsulated sunscreen in all types of cosmetic vehicles including oil free compns., with no necessary steps of heating or high shear forces. The sunscreen compns. of the present invention can comprise any acceptable UVA and/or UVB absorbing compds. at any desired ratio to obtain a desired accumulative UV screening spectrum. An aq. suspension of silica microcapsules, contg. 35.8% p-methoxycinnamate (OMC) was prepd. An oil in water emulsion contg. liq. paraffin (mineral oil) 5.00, decyl oleate 5.00, dimethicone 1.00, cetearyl alc. 1.00, glyceryl stearate 3.00, potassium cetyl phosphate 2.00, water 47.25, xanthan gum 0.15, propylene glycol 5.00, 2-bromo-2-nitropropane-1,3-diol & methylparaben & phenoxyethanol & propylbaraben 5.00, 88% lactic acid 0.10, and above silica/OMC (25% OMC in water suspension) 30.00%. [on SciFinder(R)]
High-quality self-assembled monolayers of long-chain alcs. were formed on H-terminated cryst. and porous Si surfaces under mild conditions in a 1-step reaction using iodoform as an in-situ iodinating agent. Besides the convenient conditions under which the procedure is carried out, it yields a high surface coverage and suppresses oxide formation. In-situ iodination is advantageous over other direct methods as it probably forms very reactive intermediate species, e.g. Si-I, that channel the reaction via a nucleophilic attack to form highly dense monolayers. [on SciFinder(R)]
The synthesis of polysaccharide-based sponges for the use in tissue engineering was systematically investigated. A comparison study of the branched polysaccharide arabinogalactan (AG) and the linear polysaccharide dextran in the formation of sponges by the reaction with diamines or polyamines was conducted. Three AG-based sponges were synthesized from the crosslinking reaction with different amine molecules. The sponges obtained were highly porous, rapidly swelled in water, and were stable in vitro for at least 11 weeks in aqueous media at 37 degrees C. AG-chitosan sponges were chosen as most suitable to serve as scaffolds for cell growth in tissue engineering. The biocompatibility in vivo of these sponges was evaluated by histological staining and non-invasive MRI technique after implantation in BALB/c mice. The sponge evoked an inflammatory response with vascularization of the implant. The inflammatory reaction decreased with time, indicating a healing process.
Osteoporosis is a disease manifested in drastic bone loss resulting in osteopenia and high risk for fractures. This disease is generally divided into two subtypes. The first, post-menopausal (type I) osteoporosis, is primarily related to estrogen deficiency. The second, senile (type II) osteoporosis, is mostly related to aging. Decreased bone formation, as well as increased bone resorption and turnover, are thought to play roles in the pathophysiology of both types of osteoporosis. In this study, we demonstrate in murine models for both type I (estrogen deficiency) and type II (senile) osteopenia/osteoporosis that reduced bone formation is related to a decrease in adult mesenchymal stem cell (AMSC) number, osteogenic activity, and proliferation. Decreased proliferation is coupled with increased apoptosis in AMSC cultures obtained from osteopenic mice. Recombinant human bone morphogenetic protein (rhBMP-2) is a highly osteoinductive protein, promoting osteogenic differentiation of AMSCs. Systemic intra-peritoneal (i.p.) injections of rhBMP-2 into osteopenic mice were able to reverse this phenotype in the bones of these animals. Moreover, this change in bone mass was coupled to an increase in AMSCs numbers, osteogenic activity, and proliferation as well as a decrease in apoptosis. Bone formation activity was increased as well. However, the magnitude of this response to rhBMP-2 varied among different stains of mice. In old osteopenic BALB/c male mice (type II osteoporosis model), rhBMP-2 systemic treatment also restored both articular and epiphyseal cartilage width to the levels seen in young mice. In summary, our study shows that AMSCs are a good target for systemically active anabolic compounds like rhBMP-2.
The BMP2-dependent onset of osteo/chondrogenic differentiation in the acknowledged pluripotent murine mesenchymal stem cell line (C3H10T1/2) is accompanied by the immediate upregulation of Fibroblast Growth Factor Receptor 3 (FGFR3) and a delayed response by FGFR2. Forced expression of FGFR3 in C3H10T1/2 is sufficient for chondrogenic differentiation, indicating an important role for FGF-signaling during the manifestation of the chondrogenic lineage in this cell line. Screening for transcription factors exhibiting a chondrogenic capacity in C3H10T1/2 identified that the T-box containing transcription factor Brachyury is upregulated by FGFR3-mediated signaling. Forced expression of Brachyury in C3H10T1/2 was sufficient for differentiation into the chondrogenic lineage in vitro and in vivo after transplantation into muscle. A dominant-negative variant of Brachyury, consisting of its DNA-binding domain (T-box), interferes with BMP2-mediated cartilage formation. These studies indicate that BMP-initiated FGF-signaling induces a novel type of transcription factor for the onset of chondrogenesis in a mesenchymal stem cell line. A potential role for this T-box factor in skeletogenesis is further delineated from its expression profile in various skeletal elements such as intervertebral disks and the limb bud at late stages (18.5 d.p.c.) of murine embryonic development.
One of the most salient features of technological development and progress is its tendency to agglomeration in space. Popular accounts glorify the emergence of these new global high tech ‘hot-spots’ (Business Week, 1998; Newsweek, 1998) and academic studies debate their uniqueness (Bania, Eberts and Fogarty, 1993; Castells and Hall, 1994, Pouder and St. John, 1996). However, one feature that seems to have been over-looked relates to the extent to which these agglomerations are concretely linked into their regional and national economies. If they act as integral components in their regional contexts, then we would expect some form of unique linkages to exist between them and their environs, linkages which could not exist if the concentration was located elsewhere. On the other hand, if they function purely as nodes in global networks, then the local context within which they perform will act purely as a back-drop. In this kind of abstract environment, little uniqueness is related to a specific location. The external economies of the agglomeration could have developed in similar fashion somewhere else. As Krugman notes with respect to the Los Angeles economy:
(the people of L.A.) are there because of each other: if one could uproot the whole city and move it 500 miles, the economic base would hardly be affected (Krugman 1996, p. 209).
To provide theoretical insights into the stability and dynamics of the new rare gas compounds HArF and HKrF, reaction paths for decomposition processes HRgF –> Rg + HF and HRgF –> H + Rg + F (Rg = Ar, Kr) are calculated using ab initio electronic structure methods. The bending channels, HRgF –> Rg + HF, are described by single-configurational MP2 and CCSD(T) electronic structure methods, while the linear decomposition paths, HRgF –> H + Rg + F, require the use of multi-configurational wave functions that include dynamic correlation and are size extensive. HArF and HKrF molecules are found to be energetically stable with respect to atomic dissociation products (H + Rg + F) and separated by substantial energy barriers from Rg + HF products, which ensure their kinetic stability. The results are compatible with experimental data on these systems. (C) 2002 Elsevier Science B.V. All rights reserved.
Nuclear membranes and nuclear pore complexes (NPCs) are conserved in both animals and plants. However, the lamina composition and the dimensions of NPCs vary between plants, yeast, and vertebrates. In this study, we established a protocol that preserves the structure of Caenorhabditis elegans embryonic cells for high-resolution studies with thin-section transmission electron microscopy (TEM). We show that the NPCs are bigger in C. elegans embryos than in yeast, with dimensions similar to those in higher eukaryotes. We also localized the C. elegans nuclear envelope proteins Ce-lamin and Ce-emerin by pre-embedding gold labeling immunoelectron microscopy. Both proteins are present at or near the inner nuclear membrane. A fraction of Ce-lamin, but not Ce-emerin, is present in the nuclear interior. Removing the nuclear membranes leaves both Ce-lamin and Ce-emerin associated with the chromatin. Eliminating the single lamin protein caused cell death as visualized by characteristic changes in nuclear architecture including condensation of chromatin, clustering of NPCs, membrane blebbing, and the presence of vesicles inside the nucleus. Taken together, these results show evolutionarily conserved protein localization, interactions, and functions of the C. elegans nuclear envelope.
