The traditional expected-net-present-value methods cannot properly capture the management flexibility and strategic value aspects of a fishery, and may understate its value. Instead, this paper ...develops a Real Options model to conceptualize and evaluate fishery exploitation flexibility. Specifically, general models to value the opportunity to either exploit or invest in a fishery are presented. They suffice to determine not only these values, but also the optimal policy for opening, closing, delaying and setting its harvest rate. The sustainable case in which the harvest rate equals the natural net growth function is also considered. Concerning the exploitation decision, it is found that, as could be expected, the higher the resource price the higher the value of this opportunity in both models (general and sustainable). However, the resource stock affects both models differently. As to the investment opportunity, its value is always lower than the exploitation opportunity because of investment costs. Finally, numerical simulations are run in order to illustrate the nature of the solution. Sensitivity analysis concerning the influence of the tax rate, convenience yield, risk-free interest rate and price volatility on the value of the fishery is also reported. Copyright Springer 2006
We studied the receptivity of a population of HIV-infected patients to the development of a group educational intervention in order to enhance the adherence to therapy. We designed a group ...educational activity conducted by family physicians and directed to patients with HIV infection treated with antiretrovirals for at least six months. We conducted a randomized trial that compared two interventions: an educational intervention plus individual counsel or the last option alone. We studied their clinical situation, adherence to therapy and familial support. We offered 115 patients (66.9% injection drug users (IDUs), 69.6% males) the opportunity to be included in our trial, but 73.9% of them refused. No group with four or more participants was formed. Fifty-nine per cent refused to be included claiming personal reasons and 32.9% cited trouble in their jobs. There was a non-significant trend to accept in the case of women ( p = 0.19), patients with AIDS ( p = 0.11) and non-adherent patients ( p = 0.08). This trend was significant in the group of women with AIDS ( p = 0.01) and non-adherent women ( p = 0.05). We concluded that HIV-infected patients, mainly IDUs, are not receptive to group educational programmes. The design of future interventions must take into account the patients' characteristics.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
We investigated whether monocyte-derived factors could stimulate the growth of ovarian cancer cells.
Human peripheral blood monocytes or human monocyte-like cell lines THP-1 and U-937 were cultured ...with or without macrophage colony-stimulating factor, lipopolysaccharide, or phorbol myristate acetate. Culture supernatants or recombinant cytokines were assayed for growth stimulation of ovarian cancer cell lines by tritium-thymidine incorporation and direct cell counts followed by statistical analysis with Student t test.
Conditioned medium from peripheral blood monocytes or from THP-1 or U-937 cells stimulated ovarian cancer cell growth. Interleukin-1 alpha, tumor necrosis factor-alpha, and interleukin-6 also stimulated ovarian cancer cell growth, whereas macrophage, granulocyte, and granulocyte-macrophage colony-stimulating factor did not. Concentrations of tumor necrosis factor, interleukin-1, and interleukin-6 in conditioned medium could not account for all the growth stimulation, and activity remained after neutralization of tumor necrosis factor, interleukin-1, and interleukin-6 with antibodies.
Interleukin-1, interleukin-6, tumor necrosis factor, and additional monocyte factor(s) could provide paracrine growth stimulation when monocytes are attracted to ovarian cancers that produce macrophage colony-stimulating factor.
Our purpose was to determine the effect of tumor necrosis factor-alpha on anti-oncogene expression and to investigate the relationship between the up-regulation of the p53 tumor suppressor gene and ...tumor necrosis factor-alpha-mediated apoptosis in epithelial ovarian cancer cell lines.
By means of Northern blot techniques p53 messenger ribonucleic acid expression was assayed in ovarian cancer cells. Tumor cells explanted from patients into Balb/c nude mice were exposed to supernatants from activated monocytes, activated T cells, or the recombinant cytokines interleukin-6 and tumor necrosis factor-alpha. Time- and dose-dependence of p53 up-regulation was measured. Induction of programmed cell death (apoptosis) by tumor necrosis factor-alpha was quantitated by means of a deoxyribonucleic acid fragmentation assay.
Detectable levels of messenger ribonucleic acid for p53 were seen in ovarian cancer cells. Tumor necrosis factor-alpha induced a significant up-regulation of p53 messenger ribonucleic acid levels in ovarian cancer cells grown in nude mice and in vitro, whereas interleukin-6 did not. The maximum level of induction was 8 hours, and the up-regulation of p53 was dose dependent. In addition, tumor necrosis factor-alpha induced a dose-dependent increase in deoxyribonucleic acid fragmentation.
Tumor necrosis factor-alpha induced up-regulation of p53 tumor suppressor gene expression in epithelial ovarian cancer cell lines, together with the induction of cell death by apoptosis.
Jamming in granular matter Garcimartin, A; Zuriguel, I; Maza, D ...
Experimental Chaos,
01/2004, Letnik:
742
Journal Article
Recenzirano
An array of systems can get jammed: traffic jams, compaction of granular materials, the glass transition, colloidal gels, panic and stampedes of people, foams, The question that arises is whether all ...these systems share their features in a more fundamental way, enabling us to think of a jammed system as a new state of matter. Jamming could then be amenable to be described as a phase transition. A particular experiment aimed at understanding this phenomenon is presented here. It consists of a silo filled with grains, with an orifice in the base. Grains begin to pour freely, and then - if the orifice is not much larger than several grain diameters - the flow stops because an arch is formed: it jams. By measuring the number of grains between successive jammings (an avalanche), a measurement of the jamming probability is obtained. From the features of the statistical distribution of avalanches, some interesting characteristics of this process can be grasped. In particular, the probability density function of avalanches shows a clear exponential tail, therefore the system is not critical. It can be rescaled with only one parameter, namely the mean avalanche size (or, alternatively, the jamming probability of a single grain). We pay particular attention to the study of some variables that could, in principle, influence the process in order to ascertain which are relevant to the phenomenon of jamming, and we show the existence of a critical radius for the orifice above which no jamming can occur.
Cases of zoonotic dirofilariasis infection, caused by Dirofilaria repens, occur widely throughout European, African, Middle Eastern, and Asian countries. The reports of this infection in humans in ...Spain are limited, and we herein report the case of a 43-year-old man from Elche (Alicante), Spain, who was seen with acute hyperemic reactivity of the temporal limbus of the right eye. A large nematode was visualized on examination and the intact worm was surgically removed. The parasite was identified as a mature but infertile female D repens. The level of serum antibodies against D repens was monitored for 6 months after surgery using immunoenzymatic assays. Serological results confirmed, as expected, the presence of a single worm and the parasitological cure after the surgical removal of the parasite. To our knowledge, this is the fourth autochthonous case of D repens infecting humans in Spain and also the first autochthonous case of subconjunctival localization.Arch Ophthalmol. 1998;116:1370-1372-->
Complete information concerning possible alterations in nitric oxide production in the rat brainstem trigeminal system after peripheral nerve lesion is still lacking. This being the case, density of ...NADPH-diaphorase positive neurons in the trigeminal mesencephalic nucleus after experimental infraorbital nerve transection was studied. In the lesioned side, an ipsilateral increase in NADPH-d positive neurons was found at postoperative days 4 and 6 with respect to contralateral, without changes after a 2 months period. These data suggest that nitric oxide could be involved in regeneration of afferent fibers concerned with the periodontal receptors of maxillary teeth.
Lidocaine is a local anesthetic widely used in therapeutics and as antiarrhythmic agent. However, information concerning possible alterations in the enkephalinergic system after acute treatment with ...this substance is not complete. This being the case, we focused on analyzing enkephalin immunostaining in several regions of the rat brain after lidocaine administration. We could not find significative changes in rat prosencephalon. These data might suggest that the enkephalinergic system is not altered by lidocaine.
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