615 research outputs found
Pentaquark searches at FOCUS
We find no evidence for high-energy photoproduction of pentaquarks at 1540
MeV/, 1862 MeV/, or 3099 MeV/ using decay modes ,
, and , respectively.Comment: Proceedings from talk at 2004 DPF Meeting at University of
California, Riversid
<i>Carlina acaulis</i> exhibits antioxidant activity and counteracts Aβ toxicity in <i>Caenorhabditis elegans</i>
Carlina acaulis is a medicinal plant that has shown antioxidant activity in in vitro studies, but to date no corresponding in vivo data is available. Therefore, in the present study the antioxidant activity and its impact in counteracting Aβ toxicity were studied in the Caenorhabditis elegans model. A dichloromethane extract of the roots of C. acaulis was prepared and characterised via gas-liquid-chromatography/mass-spectrometry (GLC-MS). The in vitro antioxidant activity was confirmed via 2,2-diphenyl-1-picrylhydracyl assay. The extract was further separated by thin layer chromatography into two fractions, one of which was a fraction of the dichloromethane extract of C. acaulis containing mostly Carlina oxide (CarOx). Different strains of C. elegans were employed to study the expression of hsp-16.2p::GFP as a marker for oxidative stress, delocalisation of the transcription factor DAF-16 as a possible mechanism of antioxidant activity, the effect of the drug under lethal oxidative stress, and the effect against beta-amyloid (Aβ) toxicity in a paralysis assay. The C. acaulis extract and CarOx showed high antioxidant activity (stress reduction by 47% and 64%, respectively) in C. elegans and could activate the transcription factor DAF-16 which directs the expression of anti-stress genes. In paralysis assay, only the total extract was significantly active, delaying paralysis by 1.6 h. In conclusion, in vivo antioxidant activity was shown for C. acaulis for the first time in the C. elegans model. The active antioxidant compound is Carlina oxide. This activity, however, is not sufficient to counteract Aβ toxicity. Other mechanisms and possibly other active compounds are involved in this effect
Eight Observations and 24 Research Questions About Open Source Projects: Illuminating New Realities
The rapid acceleration of corporate engagement with open source projects is drawing out new ways for CSCW researchers to consider the dynamics of these projects. Research must now consider the complex ecosystems within which open source projects are situated, including issues of for-profit motivations, brokering foundations, and corporate collaboration. Localized project considerations cannot reveal broader workings of an open source ecosystem, yet much empirical work is constrained to a local context. In response, we present eight observations from our eight-year engaged field study about the changing nature of open source projects. We ground these observations through 24 research questions that serve as primers to spark research ideas in this new reality of open source projects. This paper contributes to CSCW in social and crowd computing by delivering a rich and fresh look at corporately-engaged open source projects with a call for renewed focus and research into newly emergent areas of interest
How to tell if your cloud files are vulnerable to drive crashes
This paper presents a new challenge--verifying that a remote server is storing a file in a fault-tolerant manner, i.e., such that it can survive hard-drive failures. We describe an approach called the Remote Assessment of Fault Tolerance (RAFT). The key technique in a RAFT is to measure the time taken for a server to respond to a read request for a collection of file blocks. The larger the number of hard drives across which a file is distributed, the faster the read-request response. Erasure codes also play an important role in our solution. We describe a theoretical framework for RAFTs and offer experimental evidence that RAFTs can work in practice in several settings of interest
p53 independent epigenetic-differentiation treatment in xenotransplant models of acute myeloid leukemia
Suppression of apoptosis by TP53 mutation contributes to resistance of acute myeloid leukemia (AML) to conventional cytotoxic treatment. Using differentiation to induce irreversible cell cycle exit in AML cells could be a p53-independent treatment alternative, however, this possibility requires evaluation. In vitro and in vivo regimens of the cytosine analogue decitabine that deplete the chromatin modifying enzyme DNA methyl-transferase 1 (DNMT1) without phosphorylating p53 or inducing early apoptosis were determined. These decitabine regimens but not equimolar DNA-damaging cytarabine up regulated the key late differentiation factors CEBPε and p27/CDKN1B, induced cellular differentiation, and terminated AML cell-cycle, even in cytarabine-resistant p53- and p16/CDKN2A-null AML cells. Leukemia initiation by xeno-transplanted AML cells was abrogated but normal hematopoietic stem cell (HSC) engraftment was preserved. In vivo, the low toxicity allowed frequent drug administration to increase exposure, an important consideration for S-phase specific decitabine therapy. In xeno-transplant models of p53-null and relapsed/refractory AML, the non-cytotoxic regimen significantly extended survival compared to conventional cytotoxic cytarabine. Modifying in vivo dose and schedule to emphasize this pathway of decitabine action can bypass a mechanism of resistance to standard therapy
A cross-ecosystem comparison of temporal variability in recruitment of functionally analogous fish stocks
As part of the international MENU collaboration, variability in temporal patterns of recruitment and
spawning stock were compared among functionally analogous species from four marine ecosystems
including the Gulf of Maine/Georges Bank, the Norwegian/Barents Seas, the eastern Bering Sea and the
Gulf of Alaska. Variability was characterized by calculating coefficients of variation for each time series
and by representing the time series as anomalies. Patterns of synchrony and asynchrony in recruitment and
spawning stock indices were examined among and between ecosystems and related to observed patterns in
biophysical properties (e.g. local trophodynamics, local hydrography and large scale climate indices) using
a wide range of time series analyses, autocorrelation corrections, autoregressive processes, and
multivariate cross-correlation analyses. Of all the commonalities, the relatively similar cross-ecosystem
and within-species magnitude of variation was most notable. Of all the differences, the timing of high or
low recruitment years across both species and ecosystems was most notable. However, many of the peaks
in these indices of recruitment were synchronous across ecosystems for functionally analogous species.
Yet the relationships (or lack thereof) between recruitment anomalies and key biophysical properties
demonstrated that no one factor consistently caused large recruitment events. Our observations also
suggested that there was no routine and common set of factors that influences recruitment; often multiple
factors were of similar relative prominence. This work demonstrates that commonalities and synchronies
in recruitment fluctuations can be found across geographically very distant ecosystems, but biophysical
causes of the fluctuations are difficult to partition.
Keywords: Ecosystem, recruitment, trophodynamics, variation
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