New synchronization method for <i>Plasmodium falciparum</i>

&lt;b&gt;Background&lt;/b&gt;: Plasmodium falciparum is usually asynchronous during in vitro culture. Although various synchronization methods are available, they are not able to narrow the range of ages of parasites. A newly developed method is described that allows synchronization of parasites to produce cultures with an age range as low as 30 minutes. &lt;b&gt;Methods&lt;/b&gt;: Trophozoites and schizonts are enriched using Plasmion. The enriched late stage parasites are immobilized as a monolayer onto plastic Petri dishes using concanavalin A. Uninfected erythrocytes are placed onto the monolayer for a limited time period, during which time schizonts on the monolayer rupture and the released merozoites invade the fresh erythrocytes. The overlay is then taken off into a culture flask, resulting in a highly synchronized population of parasites. &lt;b&gt;Results&lt;/b&gt;: Plasmion treatment results in a 10- to 13-fold enrichment of late stage parasites. The monolayer method results in highly synchronized cultures of parasites where invasion has occurred within a very limited time window, which can be as low as 30 minutes. The method is simple, requiring no specialized equipment and relatively cheap reagents. &lt;b&gt;Conclusions&lt;/b&gt;: The new method for parasite synchronization results in highly synchronized populations of parasites, which will be useful for studies of the parasite asexual cell cycle

Sequential vertical gas charge into multilayered sequences controlled by central conduits

Four sets of stacked amplitude anomalies are described from a three-dimensional seismic survey acquired in Block A of the Dutch North Sea. The amplitude anomalies (AAs) have a subcircular planform and within each set they are stacked vertically: they have a high degree of spatial overlap in the vertical succession. These sets of AAs are interpreted as vertical anomaly clusters (VACs) composed of five to seven major AAs each. Seismic interpretation of the VACs and quantitative analysis of the reservoir intervals reveal that the VACs are gas-bearing silt-rich reservoirs hosted in the upper section of the Upper North Sea Group, a mixed clastic succession of Pliocene to Pleistocene age. Novel analysis based on the geometry of the individual anomalies reveals that these are likely to be the result of a gas migration process characterized by sequential upward gas charge into reservoir units and that the flow across the seals separating these reservoirs is controlled by central regions of focused fluid flow. These regions function as seal–bypass systems and are most likely formed by hydraulic fracturing

Calculating the large leakage flux of a breached hydrocarbon trap using geophysical interpretation of a paleo-gas-water contact

Integration of three-dimensional seismic and well data from the Northern Carnarvon Basin on the North West Shelf of Australia was used to assess the evidence for top seal breach of a paleo-gas accumulation. Several seismic indicators of vertical hydrocarbon leakage from the crest of the stratigraphic Mungaroo Trap point to a significant flux of gas within the past few hundred thousand years. Mapping of the top reservoir within the Triassic aged Mungaroo Formation revealed strong evidence for a paleo-gas-water contact (GWC), approximately 100 m down flank from the erosional crest of the trap. This contact conforms to structure and delimits an original volume of 1.1 trillion cubic feet (Tcf), based on reservoir property calibration from nearby wells. Mapping also revealed a present-day gas-water contact with a closed volume of 0.2 Tcf, 30 m down flank from the crest. This contact displays a discordant geometry indicative of a dynamic contact. The leakage zone is located directly above the crest of the structure. It is seismically well imaged and comprises seafloor pockmarks, shallow gas anomalies and gas hydrate anomalies. The presence of a leakage zone distributed vertically above a reservoir containing a present and paleo-GWC provides compelling evidence this trap has leaked by breaching of the top seal. Volumetric calculations using the two GWCs indicate that the Mungaroo Trap has been depleted by 0.9–1.1 Tcf. A dynamic-GWC indicates the leakage event within the trap has occurred recently. Analysis of dating of horizons correlated to the seafloor pockmarks places the leakage event at sometime within the last 300 Ka

Arrested versus active silica diagenesis reaction boundaries—A review of seismic diagnostic criteria

This paper evaluates previously proposed diagnostic criteria that can be used to determine whether or not there is active migration of the opal-A to opal-CT transition zone (TZA/CT). The criteria are based on the interpretation of 2D and 3D seismic surveys and are therefore geometrical. They involve an assessment of the relationship of the TZA/CT with polygonal fault systems, differential compaction structures and tectonic folds. The most robust evidence for an inactive ‘reaction front’ between opal-A and opal-CT bearing sediments is the discordance of the TZA/CT relative to present-day isotherms. Any of these may be persuasive as diagnostic criteria for the upward arrest of the diagenetic transformation at a regional scale, but actual truncation of the TZA/CT at the modern seabed is definitive for arrested diagenesis. This study argues that diagenetic assessment based solely on a single criterion independently is not reliable as an indicator for the current state of a silica transition. As a conclusion, the analysed seismic/structural criteria should be synthesised to provide a more credible interpretation for silica diagenesis. The use of modern 2D and 3D seismic data for the reconstruction of the diagenetic history of opaline silica bearing sediments offers a new approach to the study of silica diagenesis at a regional scale

Late Cretaceous to Early Cenozoic initiation of rifting of the Windhoek Graben, Namibia

The Windhoek Graben is a north-south trending rift in central Namibia that forms a prominent topographic feature bisecting an area of plateau uplift. It occupies a potentially crucial role in the propagation of the Late Cenozoic Southwest African Rift system regarding a possible continuation to the west of the Eiseb Rift. It is an unusual example of intra-continental rifting because it has no significant sediment fill associated with the period of active rifting, and hence the timing of rift activity and its tectonic relevance has not hitherto been established. To constrain the age of the Windhoek Graben we examine its regional geomorphic context and its relationship to four sites of igneous activity in the central Namibian Highlands. Two of these consist of clusters of eroded phonolitic tholoid bodies that have yielded 40Ar/39Ar dates of 32 Ma and 52 Ma, respectively, that we use to bracket the age of formation of a prominent remnant land surface, termed here the P52 Surface. From previous mapping of older intrusive igneous bodies, we argue that an even older land surface is partially preserved on the highest features in the area, and this surface (termed PRS) defines an initial domally uplifted surface from which initial drainage radiated, and onto which the earliest volcanic products associated with the Graben were erupted. In particular, the strong similarity in dyke and fault orientations is used to argue for a causal connection between the earliest magmatic activity and the onset of rifting. Long range correlation of PRS into the adjacent Aranos Basin strongly suggests a Late Cretaceous age for this earliest magmatic activity and the onset of rifting, but we cannot exclude a younger origin, any time up to the Early Eocene

Impact Factor: outdated artefact or stepping-stone to journal certification?

A review of Garfield's journal impact factor and its specific implementation as the Thomson Reuters Impact Factor reveals several weaknesses in this commonly-used indicator of journal standing. Key limitations include the mismatch between citing and cited documents, the deceptive display of three decimals that belies the real precision, and the absence of confidence intervals. These are minor issues that are easily amended and should be corrected, but more substantive improvements are needed. There are indications that the scientific community seeks and needs better certification of journal procedures to improve the quality of published science. Comprehensive certification of editorial and review procedures could help ensure adequate procedures to detect duplicate and fraudulent submissions.Comment: 25 pages, 12 figures, 6 table

Ambulatory assessment of psychophysiological stress among police officers: A proof-of-concept study.

Occupational stress has been widely recognized as a global challenge and has received increased attention by the academic community. Ambulatory Assessment methodologies, combining psychophysiological measures of stress, offer a promising avenue for future prevention and/or rehabilitation stress research. Considering that policing is well known for being a particularly stressful occupation, Emergency Responders Officers (EROs) stress levels were investigated. Particularly, this study analyzed: (i) physiological stress data obtained during shifts and compared these data with baseline levels (days off), as well as (ii) with normative values for healthy populations; (iii) stress symptoms differences from beginning to end of shift; (iv) stress events and events intensity and (v) the acceptability and feasibility of this proof-of-concept study in a highly stressful occupation. A Geo-location event system was used to help retrospective accounts of psychological stress, combined with electrocardiogram (ECG) data and mobile self-reports, that include stress symptoms, event types and event intensity. Results suggest that EROs experience high levels of stress (both on-duty and off duty) when compared to healthy populations. Stress symptoms increase from the beginning to end of the shift. However, the mean events intensity was very low. It can be concluded that stress may not always be diagnosed when using merely self-reports. These findings highlight the importance of combining both self-report and physiological stress measures in occupational health contexts. Finally, results confirm the acceptability and feasibility of the multi-method used. Key implications for policy makers and applied practitioners in the area of occupational health and future research directions are discussed