45 research outputs found
Fourteen degrees of latitude and a continent apart: comparison of lichen activity over two years at continental and maritime Antarctic sites
There are marked declines in precipitation, mean temperatures and the number of lichen species with increasing latitude in Antarctica. However, it is not known which factors are the predominant controllers of biodiversity changes. Results are presented from over two years of almost continuous monitoring of both microclimate and activity in lichens at Livingston Island, South Shetland Islands, 62°S, and Botany Bay, Ross Sea region, 77°S. Lichen activity was evident over a much longer period at Livingston Island, (3694 versus 897 hours) and could occur in any month whereas it was almost completely confined to the period NovemberâFebruary at Botany Bay. Mean air temperatures were much lower at Botany Bay (-18° compared to -1.5°C at Livingston Island), but the temperatures at which the lichens were active were almost identical at around 2°C at both sites. When the lichens were active incident light at Botany Bay was very much higher. The differences are related to the availability of meltwater which only occurs at times of high light and warm temperatures at Botany Bay. Temperature as a direct effect does not seem to explain the differences in biodiversity between the sites, but an indirect effect through active hours is much more probable. In addition there are negative effects of stresses such as high light and extreme winter cold at Botany Bay
Partial Sums on the Ultra-Wide Word RAM
We consider the classic partial sums problem on the ultra-wide word RAM model
of computation. This model extends the classic -bit word RAM model with
special ultrawords of length bits that support standard arithmetic and
boolean operation and scattered memory access operations that can access
(non-contiguous) locations in memory. The ultra-wide word RAM model captures
(and idealizes) modern vector processor architectures.
Our main result is a new in-place data structure for the partial sum problem
that only stores a constant number of ultraword in addition to the input and
supports operations in doubly logarithmic time. This matches the best known
time bounds for the problem (among polynomial space data structures) while
improving the space from superlinear to a constant number of ultrawords. Our
results are based on a simple and elegant in-place word RAM data structure,
known as the Fenwick tree. Our main technical contribution is a new efficient
parallel ultra-wide word RAM implementation of the Fenwick tree, which is
likely of independent interest.Comment: Extended abstract appeared at TAMC 202
DNA methylation at an enhancer of the three prime repair exonuclease 2 gene (TREX2) is linked to gene expression and survival in laryngeal cancer
Background: Genetic aberrations in DNA repair genes are linked to cancer, but less is reported about epigenetic regulation of DNA repair and functional consequences. We investigated the intragenic methylation loss at the three prime repair exonuclease 2 (TREX2) locus in laryngeal (nâ=â256) and colorectal cancer cases (nâ=â95) and in pan-cancer data from The Cancer Genome Atlas (TCGA).
Results: Significant methylation loss at an intragenic site of TREX2 was a frequent trait in both patient cohorts (pâ=â0.016 and <â0.001, respectively) and in 15 out of 22 TCGA studies. Methylation loss correlated with immunohistochemically staining for TREX2 (pâ<â0.0001) in laryngeal tumors and improved overall survival of laryngeal cancer patients (pâ=â0.045). Chromatin immunoprecipitation, demethylation experiments, and reporter gene assays revealed that the region of methylation loss can function as a CCAAT/enhancer binding protein alpha (CEBPA)-responsive enhancer element regulating TREX2 expression.
Conclusions: The data highlight a regulatory role of TREX2 DNA methylation for gene expression which might affect incidence and survival of laryngeal cancer. Altered TREX2 protein levels in tumors may affect drug-induced DNA damage repair and provide new tailored therapies
Membrane fusion studied by colloidal probes
Membrane-coated colloidal probes combine the benefits of solid-supported membranes with a more complex three-dimensional geometry. This combination makes them a powerful model system that enables the visualization of dynamic biological processes with high throughput and minimal reliance on fluorescent labels. Here, we want to review recent applications of colloidal probes for the study of membrane fusion. After discussing the advantages and disadvantages of some classical vesicle-based fusion assays, we introduce an assay using optical detection of fusion between membrane-coated glass microspheres in a quasi two-dimensional assembly. Then, we discuss free energy considerations of membrane fusion between supported bilayers, and show how colloidal probes can be combined with atomic force microscopy or optical tweezers to access the fusion process with even greater detail
Original article: role of adjuvant chemotherapy in a perioperative chemotherapy regimen for gastric cancer
Background
Multimodal treatment strategies â perioperative chemotherapy (CTx) and radical surgery â are currently accepted as treatment standard for locally advanced gastric cancer. However, the role of adjuvant postoperative CTx (postCTx) in addition to neoadjuvant preoperative CTx (preCTx) in this setting remains controversial.
Methods
Between 4/2006 and 12/2013, 116 patients with locally advanced gastric cancer were treated with preCTx. 72 patients (62 %), in whom complete tumor resection (R0, subtotal/total gastrectomy with D2-lymphadenectomy) was achieved, were divided into two groups, one of which receiving adjuvant therapy (nâ=â52) and one without (nâ=â20). These groups were analyzed with regard to survival and exclusion criteria for adjuvant therapy.
Results
Postoperative complications, as well as their severity grade, did not correlate with fewer postCTx cycles administered (pâ=ân.s.). Long-term survival was shorter in patients receiving postCTx in comparison to patients without postCTx, but did not show statistical significance. In per protocol analysis by excluding two patients with perioperative death, a shorter 3-year survival rate was observed in patients receiving postCTx compared to patients without postCTx (3-year survival: 71.2 % postCTx group vs. 90.0 % non-postCTx group; pâ=â0.038).
Conclusion
These results appear contradicting to the anticipated outcome. While speculative, they question the value of post-CTx. Prospectively randomized studies are needed to elucidate the role of postCTx
Hematological and Biochemical Assessment of Two Species of Freshwater Mussels, Quadrula quadrula
âWestforschungâ
Die Frage nach der UnterstĂŒtzung des nationalsozialistischen
Regimes durch die deutschen
Historiker und den KontinuitÀtslinien deutscher
Historiografie ĂŒber staatliche ZĂ€suren hinweg
ist bis heute ein aktuelles Thema. Dabei wird
zwar der generelle Forschungsbefund einer
âLegitimationswissenschaftâ kaum bestritten,
doch besteht unter anderem Uneinigkeit hinsichtlich
des AusmaĂes und der Konsequenzen
dieses Engagements und dessen Bedeutung.
Die bis heute kontrovers diskutierten Fragen
nach KontinuitÀt, DiskontinuitÀt, Ursprung
und Bedeutung des Verhaltens von Geisteswissenschaftlern
im NS-Regime werden von
den Herausgebern und Autoren des kĂŒrzlich
erschienenen Sammelbandes âGriff nach dem
Westen. Die âWestforschungâ der völkisch-nationalen
Wissenschaften zum nordwesteuropÀischen
Raum 1919-1960â wieder aufgegriffen.
Die Vielzahl von BeitrÀgen dieses Bandes, aber
auch das zeitgleiche Erscheinen weiterer Veröffentlichung
etwa zur deutschen Ostforschung
legen eine Betrachtungsweise nahe, bei der
nicht allein die Details anhand einer einzelnen
Publikation erörtert werden. Vielmehr sollte
auf das Symptomatische der Diskussion hingewiesen
werden. Insgesamt gibt der vorliegende
Band die Abfolge der Artikel und DiskussionsbeitrÀge
des Forums, welches auf H-Soz-u-Kult
veröffentlicht wurde, wider. DarĂŒber hinaus
wurden weiterfĂŒhrende Artikel dem Band hinzugefĂŒgt