983 research outputs found
Inflation after WMAP3
I discuss the current status of inflationary cosmology in light of the recent
WMAP 3-year data release. The basic predictions of inflation are all supported
by the data. Inflation also makes predictions which have not been well tested
by current data but can be by future experiments, most notably a deviation from
a scale-invariant power spectrum and the production of primordial gravitational
waves. A scale-invariant spectrum is disfavored by current data, but not
conclusively. Tensor modes are currently poorly constrained, and slow-roll
inflation does not make an unambiguous prediction of the expected amplitude of
primordial gravitational waves. A tensor/scalar ratio of is
within reach of near-future measurements.Comment: To appear in the proceedings of Colliders to Cosmic Rays 2007. 8
pages, 2 figures. (V2: Minor typo corrected
Regulation of 92-kD gelatinase release in HL-60 leukemia cells
Matrix metalloproteinase 9 (MMP-9), also known as 92-kD type IV collagenase/gelatinase, is believed to play a critical role in tumor invasion and metastasis. Here, we report that MMP-9 was constitutively released from the human promyelocytic cell line HL-60 as determined by zymographic analysis. Tumor necrosis factor-alpha (TNF-alpha) enhanced the enzyme release threefold to fourfold and the protein kinase C (PKC) activator and differentiation inducer 12-O-tetradecanoylphorbol-13- acetate (TPA) eightfold to ninefold. Gelatinase induction by TNF-alpha and TPA was inhibited by actinomycin D or cycloheximide, indicating that de novo protein synthesis was required. Neutralizing monoclonal antibodies to TNF-alpha (anti-TNF-alpha) decreased the basal MMP-9 release of these cells. In addition, these antibodies also significantly interfered with the TPA-induced enzyme release. Agents that inhibit TNF-alpha expression in HL-60 cells, such as pentoxifylline and dexamethasone, completely abrogated both the constitutive and TPA-evoked MMP-9 release. Diethyldithiocarbamate, which is known to stimulate TNF-alpha production in HL-60 cells, exerted a positive effect on MMP-9 release in untreated cells but was inhibitory in TPA-treated HL-60 cells. The PKC inhibitor staurosporine at low concentrations (100 ng/mL) caused a significant augmentation of MMP-9 release in untreated cultures that was blocked by the addition of anti-TNF-alpha. High concentrations (2 mumol/L) of staurosporine completely abolished the extracellular enzyme activity both in untreated and TPA-stimulated cells. These results suggest, that TNF- alpha is required for basal and PKC-mediated MMP-9 release in HL-60 leukemia cells. Thus, MMP-9 secretion may be regulated by TNF-alpha not only in a paracrine but also in an autocrine fashion. This may potentiate the matrix degradative capacity of immature leukemic cells in the processes of bone marrow egress and the evasion of these cells into peripheral tissue
Self-Stabilizing Supervised Publish-Subscribe Systems
In this paper we present two major results: First, we introduce the first
self-stabilizing version of a supervised overlay network by presenting a
self-stabilizing supervised skip ring. Secondly, we show how to use the
self-stabilizing supervised skip ring to construct an efficient
self-stabilizing publish-subscribe system. That is, in addition to stabilizing
the overlay network, every subscriber of a topic will eventually know all of
the publications that have been issued so far for that topic. The communication
work needed to processes a subscribe or unsubscribe operation is just a
constant in a legitimate state, and the communication work of checking whether
the system is still in a legitimate state is just a constant on expectation for
the supervisor as well as any process in the system
Kapitalstock und demographische Komponente - Wie kann die Rentenversicherung reformiert werden?
Der Artikel untersucht die Produktions- und Beschäftigungswirkungen alternativer Reformoptionen zur Finanzierung der gesetzlichen Rentenversicherung. Diskutiert werden die Erweiterung der Rentenformel um eine demographische Komponente und die Bildung eines steuerfinanzierten Teilkapitalstocks als Ergänzung zum Umlageverfahren. Kurzfristig verursacht der Aufbau des Kapitalstocks Belastungen. Langfristig überwiegen jedoch die expansiven Effekte, weil die ansonsten notwendigen Beitragssteigerungen unterbleiben
From sea to land and beyond : new insights into the evolution of euthyneuran Gastropoda (Mollusca)
Background The Euthyneura are considered to be the most successful and diverse group of Gastropoda. Phylogenetically, they are riven with controversy. Previous morphology-based phylogenetic studies have been greatly hampered by rampant parallelism in morphological characters or by incomplete taxon sampling. Based on sequences of nuclear 18S rRNA and 28S rRNA as well as mitochondrial 16S rRNA and COI DNA from 56 taxa, we reconstructed the phylogeny of Euthyneura utilising Maximum Likelihood and Bayesian inference methods. The evolution of colonization of freshwater and terrestrial habitats by pulmonate Euthyneura, considered crucial in the evolution of this group of Gastropoda, is reconstructed with Bayesian approaches. Results We found several well supported clades within Euthyneura, however, we could not confirm the traditional classification, since Pulmonata are paraphyletic and Opistobranchia are either polyphyletic or paraphyletic with several clades clearly distinguishable. Sacoglossa appear separately from the rest of the Opisthobranchia as sister taxon to basal Pulmonata. Within Pulmonata, Basommatophora are paraphyletic and Hygrophila and Eupulmonata form monophyletic clades. Pyramidelloidea are placed within Euthyneura rendering the Euthyneura paraphyletic. Conclusion Based on the current phylogeny, it can be proposed for the first time that invasion of freshwater by Pulmonata is a unique evolutionary event and has taken place directly from the marine environment via an aquatic pathway. The origin of colonisation of terrestrial habitats is seeded in marginal zones and has probably occurred via estuaries or semi-terrestrial habitats such as mangroves
Keine Beschäftigungseffekte durch Verkürzung der tariflichen Wochenarbeitszeit
Der Beitrag untersucht die Beschäftigungseffekte einer generellen Verkürzung der tariflichen Wochenarbeitszeit. Auf der Basis panelökonometrischer Methoden kann für das Verarbeitende Gewerbes keine Beschäftigungswirkung nachgewiesen werden. Damit ist eine generelle Absenkung der tariflichen Arbeitszeit kein geeignetes Mittel, um den Beschäftigtenstand zu erhöhen.
Kapitalstock und demographische Komponente - Wie kann die Rentenversicherung reformiert werden?
Der Artikel untersucht die Produktions- und Beschäftigungswirkungen alternativer Reformoptionen zur Finanzierung der gesetzlichen Rentenversicherung. Diskutiert werden die Erweiterung der Rentenformel um eine demographische Komponente und die Bildung eines steuerfinanzierten Teilkapitalstocks als Ergänzung zum Umlageverfahren. Kurzfristig verursacht der Aufbau des Kapitalstocks Belastungen. Langfristig überwiegen jedoch die expansiven Effekte, weil die ansonsten notwendigen Beitragssteigerungen unterbleiben.
Generelle Verkürzung der Wochenarbeitszeit verdrängt ungelernte Arbeitnehmer
Bei einer Verkürzung der tariflichen Wochenarbeitszeit sind strukturelle Effekte zu erwarten, die sich unter anderem in der Arbeitsnachfrage nach spezifischen Qualifikationen zeigen. Eine generelle Verkürzung der tariflichen Wochenarbeitszeit löst Anpassungen der Arbeitsnachfrage aus, die vor allem zu Lasten ungelernter Arbeit gehen. Damit ergeben sich Be-schäftigungsverluste im Bereich unterer Qualifikationen.
Kapitalstock und demographische Komponente - Wie kann die Rentenversicherung reformiert werden?
Der Artikel untersucht die Produktions- und Beschäftigungswirkungen alternativer Reformoptionen zur Finanzierung der gesetzlichen Rentenversicherung. Diskutiert werden die Erweiterung der Rentenformel um eine demographische Komponente und die Bildung eines steuerfinanzierten Teilkapitalstocks als Ergänzung zum Umlageverfahren. Kurzfristig verursacht der Aufbau des Kapitalstocks Belastungen. Langfristig überwiegen jedoch die expansiven Effekte, weil die ansonsten notwendigen Beitragssteigerungen unterbleiben.
- …