bluuebunny/crossref_metadata_2025 huggingface dataset:
An assessment of the use of ocean gliders to undertake acoustic measurements of zooplankton: the distribution and density of Antarctic krill (Euphausia superba) in the Weddell Sea.
Authors: Guihen Damien , Fielding Sophie , Murphy Eugene J. , Heywood Karen J. , Griffiths Gwyn
Published: July 2014

A calibrated 120 kHz single‐beam echo‐sounder was integrated into an ocean glider and deployed in the Weddell Sea, Southern Ocean. The glider was deployed for two short periods in January 2012, in separate survey boxes on the continental shelf to the east of the Antarctic Peninsula, to assess the distribution of Antarctic krill (Euphausia superba). During the glider missions, a research vessel undertook acoustic transects using a calibrated, hull‐mounted, multi‐frequency echo‐sounder. Net hauls were taken to validate acoustic targets and parameterize acoustic models. Krill targets were identified using a thresholded schools analysis technique (SHAPES), and acoustic data were converted to krill density using the stochastic distorted‐wave Born approximation (SDWBA) target strength model. A sensitivity analysis of glider pitch and roll indicated that, if not taken into account, glider orientation can impact density estimates by up to 8‐fold. Glider‐based, echo‐sounder—derived krill density profiles for the two survey boxes showed features coherent with ship‐borne measurements, with peak densities in both boxes around a depth of 60 m. Monte Carlo simulation of glider subsampling of ship‐borne data showed no significant difference from observed profiles. Simulated glider dives required at least an order of magnitude more time than the ship to similarly estimate the abundance of krill within the sample regions. These analyses highlight the need for suitable sampling strategies for glider‐based observations and are our first steps toward using autonomous underwater vehicles for ecosystem assessment and long‐term monitoring. With appropriate survey design, gliders can be used for estimating krill distribution and abundance.
Autonomous bed‐sediment imaging‐systems for revealing temporal variability of grain size
Authors: Buscombe Daniel , Rubin David M. , Lacy Jessica R. , Storlazzi Curt D. , Hatcher Gerald , Chezar Henry , Wyland Robert , Sherwood Christopher R.
Published: July 2014

We describe a remotely operated video microscope system, designed to provide high‐resolution images of seabed sediments. Two versions were developed, which differ in how they raise the camera from the seabed. The first used hydraulics and the second used the energy associated with wave orbital motion. Images were analyzed using automated frequency‐domain methods, which following a rigorous partially supervised quality control procedure, yielded estimates to within 20% of the true size as determined by on‐screen manual measurements of grains. Long‐term grain‐size variability at a sandy inner shelf site offshore of Santa Cruz, California, USA, was investigated using the hydraulic system. Eighteen months of high frequency (min to h), high‐resolution (µm) images were collected, and grain size distributions compiled. The data constitutes the longest known high‐frequency record of seabed‐grain size at this sample frequency, at any location. Short‐term grain‐size variability of sand in an energetic surf zone at Praa Sands, Cornwall, UK was investigated using the ‘wave‐powered’ system. The data are the first high‐frequency record of grain size at a single location of a highly mobile and evolving bed in a natural surf zone. Using this technology, it is now possible to measure bed‐sediment‐grain size at a time‐scale comparable with flow conditions. Results suggest models of sediment transport at sandy, wave‐dominated, nearshore locations should allow for substantial changes in grain‐size distribution over time‐scales as short as a few hours.
Impact of collection container material and holding times on sample integrity for mercury and methylmercury in water
Authors: Riscassi Ami , Miller Carrie L. , Brooks Scott C.
Published: July 2014

Mercury (Hg) and methylmercury (MeHg) concentrations in streamwater can vary on short timescales (hourly or less) during storm flow and on a diel cycle; the frequency and timing of sampling required to accurately characterize these dynamics may be difficult to accomplish manually. Automated sampling can assist in sample collection; however use has been limited for Hg and MeHg analysis due to stability concerns during extended storage times. We examined the viability of using automated samplers with disposable low‐density polyethylene (LDPE) sample bags to collect streamwater with high levels of Hg (>45 ng L−1) and moderate levels of MeHg (0.2−2.5 ng L−1). Specifically, we investigated the effect of holding times ranging from hours to days on streamwater collected during baseflow and storm flow. Unfiltered and filtered Hg and MeHg concentrations decreased with increases in time before sample processing; holding times of 24 hours or less resulted in concentration changes (mean 11 ± 7% different) similar to variability in duplicates collected manually during analogous field conditions (mean 7 ± 10% different). Comparisons of samples collected with manual and automated techniques (holding times < 24 h) throughout a year for a wide range of stream conditions were also found to be similar to differences observed between duplicate grab samples. These results demonstrate automated sampling into LDPE bags can be effectively used to collect streamwater for Hg and MeHg analysis, and encourage the testing of these materials and methods for implementation in other aqueous systems where high‐frequency sampling is warranted.
Quantification of free, dissolved combined, particulate, and total amino acid enantiomers using simple sample preparation and more robust chromatographic procedures
Authors: Escoubeyrou Karine , Tremblay Luc
Published: July 2014

The goal of this work was to develop amino acid (AA) quantification protocols using simple sample preparation steps and new chromatographic conditions optimized for a hybrid (organo‐silica) C18 column resistant to alkaline samples in borate buffer. This resistance allows for larger injection volumes, and thus stronger detected signals (~3 times stronger), higher precision, and lower analysis costs compared with previous methods. Enantiomeric and non‐enantiomeric separations of AA were possible in less than 0.5 mL of AA‐poor water samples. Results showed that a high salt content and the sample treatment do not lead to AA loss or separation interference. The accuracy and the precision of AA quantification in a natural sample strongly depend on the blank correction. The limits of detection, measured based on the variability of these blanks, were 0.007–3.6 nM depending on the AA. The protocols developed here allow for the quantification of all forms of AA (i.e., free, dissolved combined, particulate, and total) in most natural waters, including deep ocean waters. It was even possible to quantify many AA in ultrapure water after blank correction. Despite the injection of a relatively high volume (100 µL) of alkaline borate solutions, the hybrid C18 column showed no sign of performance degradation after more than 700 injections. This durability reduces the cost of AA analysis and provides a more consistent separation. The analysis time can be greatly reduced by the use of stationary phases with a nonporous core and extended pH stability as they become available.
The exponentially fed batch culture as a reliable alternative to conventional chemostats
Authors: Fischer Robert , Andersen Tom , Hillebrand Helmut , Ptacnik Robert
Published: July 2014

Chemostats and their common alternative, semicontinuous cultures, play a pivotal role as model systems in aquatic ecology. Despite the theoretical and conceptual advantages chemostat systems offer, they can be challenging to set up and operate. One such challenge is to obtain a representative sample volume without changing the dilution rate, another is to ensure that the outflow constitutes an unbiased loss of the chemostat contents. Here, we present a specific system, the exponentially fed‐batch culture (EFB), as an economic, simply operable albeit reliable alternative to conventional chemostats. The EFB is well‐known in biotechnological research and in industrial bioengineering. Like a conventional chemostat, the EFB culture is a continuous culture method. In contrast to a conventional chemostat, there is no outflow. To ensure a constant dilution rate and therefore steady state, fresh medium is continuously supplied proportional to the current culture volume. Hence culture volume and medium supply rate both increase exponentially with time until sampling, when the volume is set back to the initial state. This allows taking large sample volumes without disturbing the steady state of the experimental unit. Here we compare the performance of the exponentially fed‐batch culture with a conventional chemostat and a semicontinuous system by growing a green algae until steady state is reached. Most pronounced differences were found between semicontinuous system and the two continuous methods. Results from the EFB and chemostat were very similar. However, a bias in the sampling of the chemostat resulted in accumulation of biomass relative to the EFB.
Experimental dead zones: two designs for creating oxygen gradients in aquatic ecological studies
Authors: Bodamer Betsy L. , Bridgeman Thomas B.
Published: July 2014

Hypoxia is commonly defined as dissolved oxygen (DO) concentrations below 2 mg L−1. The occurrence of hypoxia within freshwater and marine ecosystems is stressful for respiring organisms across all trophic levels, leading to changes in community diversity, altered trophic interactions, and decreased physiological fitness of organisms. Whereas many field studies have identified changes in animal diets and species distribution due to hypoxia, the behavioral changes that drive these patterns are poorly understood. Additionally, many laboratory studies that subject organisms to a fixed DO concentration may not be entirely applicable to natural environments because many organisms are capable of sensing and avoiding hypoxic areas. Herein we describe two experimental tank systems developed to study the effects of oxygen gradients on fish behavior. These systems are novel in that 1) fish and potentially other aquatic organisms can freely move between hypoxic and well oxygenated areas, 2) the thermocline or oxycline is easily adjusted for multiple treatment levels, 3) they are large enough to study fish behavior on an ecological scale, and 4) are constructed with affordable, readily available materials and are easily maintained. In both systems, we were able to conduct fish behavior studies under stable thermal and oxic stratification comparable to conditions found in temperate freshwater lakes.
Direct analysis of volatile fatty acids in marine sediment porewater by two‐dimensional ion chromatography‐mass spectrometry
Authors: Glombitza Clemens , Pedersen Jeanette , Røy Hans , Jørgensen Bo Barker
Published: July 2014

Volatile fatty acids (VFAs) are key intermediates in the microbial food web. However, the analysis of low concentrations of VFAs in marine porewater is hampered by interference from high concentrations of inorganic ions. Published methods often use sample pretreatment, including distillation or derivatization, to overcome this problem. This is not only labor intensive but also increases the risk of contamination. We have developed an analytical procedure that enables the direct quantification of several VFAs (formate, acetate, propionate, butyrate, valerate, pyruvate, and lactate) in marine porewater by two‐dimensional ion chromatography‐mass spectrometry (2D IC‐MS). The first chromatographic dimension is used to separate the VFAs from the inorganic ions whereas the second dimension separates the individual VFAs. Quantification and identification are achieved by online mass spectrometry in selected ion monitoring mode. No sample pretreatment is required and statistically determined detection limits are below 25 ppb (µg L−1). The method can also be used without the online coupling to a mass spectrometer. In the latter case, quantification of the VFAs can be done by the conductivity detector signal of the second dimension with the limitation that lactate cannot be quantified due to signal interference with an unidentified peak and pyruvate and valerate have slightly higher detection limits (<100 ppb).
An improved sample preparation method for imaging microstructures of fine‐grained marine sediment using microfocus X‐ray computed tomography and scanning electron microscopy
Authors: Uramoto Go‐Ichiro , Morono Yuki , Uematsu Katsuyuki , Inagaki Fumio
Published: July 2014

Marine sediments are composed of various mineral species and are characterized by micro‐scale grain fabric. The arrangements and interactions of component particles place critical constraints on the physical, chemical, and biological processes that occur in subseafloor environments. However, the observation of nearly intact microstructures is difficult, especially in soft, muddy sediments because of their high water content and the presence of organic molecules. In this study, a modified version of the resin‐embedding method generally used for biological samples was applied to marine sediment sample preparation. The new method was compared with the conventional t‐butyl alcohol freeze‐drying method using microfocus X‐ray computed tomography (µXCT) and scanning electron microscopy (SEM). The µXCT and SEM results showed that all t‐butyl alcohol freeze‐dried sediment samples contained microstructural disturbances (e.g., cracks). In contrast, no cracks were observed in the samples prepared using the new resin‐embedding method, and the microstructural arrangement of the sediment particles were clearly visible. In addition, the porosity visible from SEM images of the resin‐embedded samples was similar to that measured using the moisture and density method, providing additional evidence that the microstructures of the resin‐embedded samples were well preserved. The resin‐embedding method allowed observation of the limited contact of the fine particles in clayey sediments, the clay microaggregates throughout the continental margin to pelagic sediments, and the presence of organic materials in environmental sediments. This modified biological resin‐embedding method is suitable for the detailed observation and characterization of fine‐grained marine sediment microstructure.
Characterization and field test of an in situ multi‐platform optical sensor
Authors: Ng Chee‐Loon , Teo Wei‐Kiat , Cai Hui‐Ting , Hemond Harold F.
Published: July 2014

The characterization and field testing of a compact in situ optical instrument using fluorescence, absorbance, and scattering to identify and quantify contaminants and natural substances in water bodies are described. The instrument, based on a technology named LEDIF (LED‐Induced Fluorescence) developed by Ng et al. (2012a) was configured for in situ long‐term continuous monitoring at a fixed location. The optical performance and sensing capabilities of the instrument were assessed by calibrating against laboratory‐prepared and commercial standards, and compared with several commercial sensors and published values. The effects on sensor response of temperature, pressure, and particle interference due to turbidity and total suspended solids were assessed and reported. Instrumental baseline shift over time, instrument detection limits, and the capability of LEDIF to determine characteristics such as quantum yield and intramolecular deactivation of fluorescence response, were also assessed. Experimental results match well with results from commercial instruments and published data. To demonstrate field deployment, the LEDIF instrument was installed at Chinese Garden of Singapore for longterm continuous monitoring of chlorophyll a (Chl a) and turbidity at a management‐selected location. The analytes were chosen based on management's needs in recording temporal trends of algal biomass and water cloudiness to develop effective controls of inflow and outflow water quality. A monitoring record showing the temporal response of algal biomass to ambient conditions and turbidity variations is presented and discussed.
A hierarchical zero‐inflated model for species compositional data—from individual taxon responses to community response
Authors: Qian Song S. , Cuffney Thomas F.
Published: July 2014

Healthy macroinvertebrate communities are typically composed of a few abundant taxa and many relatively rare taxa. These rare taxa tend to be sensitive to pollution and, in aggregate, are important indicators of water quality (e.g., EPT taxa richness that combines Ephemeroptera, Plecoptera, and Trichoptera taxa). Rare taxa lead to community data sets that contain large numbers of zero values that are often a source of difficulty in data processing and analysis. A hierarchical zero‐inflated Poisson model is developed to study the responses to watershed urbanization of a group of macroinvertebrates taxa (EPT taxa) often used as indicators of good water quality and a healthy stream ecosystem. The zero‐inflated Poisson model is parameterized with a unimodal curve for the abundance model and a logit‐linear model for the zero model. The hierarchical model is used to integrate responses of individual taxa into a community level response. The emphasis of the model is on estimating the probability that an observed 0 represents the true absence of a taxon. By modeling the probability of true absence as a function of watershed level urbanization intensity both at individual taxon level and at the community level, we are able to develop a stressor‐specific tolerance indicator to (1) separate truly sensitive EPT taxa from more tolerant taxa, and (2) compare the responses of different communities to the same stressor or responses of the same community in different regions. We document the development of the model and the process of integrating individual taxon models into a community model. The model is applied to a data set collected for study of the effect of urbanization on stream ecosystems.
Assessment of a subcellular metal partitioning protocol for aquatic invertebrates: preservation, homogenization, and subcellular fractionation
Authors: Rosabal Maikel , Hare Landis , Campbell Peter G.C.
Published: July 2014

Measurements of the subcellular partitioning of trace metals have been used to predict assimilation efficiencies for metals between trophic levels and to evaluate metal detoxification mechanisms in aquatic organisms. Using field‐collected larvae of the insect Chaoborus, we assessed the performance of two preservation protocols, three homogenization treatments, and a cell fractionation protocol to determine the best combination of techniques for assessing the subcellular partitioning of Cd, Cu, Ni, and Zn. Preservation of larval samples for either 2 years at −80°C or 1 year at −80°C or −196°C had little influence on the subcellular partitioning of these metals. Using several marker enzymes, i.e., cytochrome C oxidase and citrate synthase for mitochondria, β‐hexosaminidase for lysosomes, and lactate dehydrogenase for the cytosol, we show that optimal and high‐yield homogenization is achieved using a combination of mechanical disruption using a micro‐pestle followed by vortexing and that the subsequent fractionation procedure employing differential centrifugation/NaOH digestion was effective. We conclude that the preservation and homogenization protocols as well as the fractionation procedure that we tested using Chaoborus larvae can serve as a model approach for improving current protocols and for designing protocols for previously untested biological samples.
Prokaryotic cells separated from sediments are suitable for elemental composition analysis
Authors: Neveu Marc , Poret‐Peterson Amisha T. , Lee Zarraz M.P. , Anbar Ariel D. , Elser James J.
Published: July 2014

Cell‐sediment separation methods can potentially enable determination of the elemental composition of microbial communities by removing the sediment elemental contribution from bulk samples. We demonstrate that a separation method can be applied to determine the composition of prokaryotic cells. The method uses chemical and physical means to extract cells from benthic sediments and mats. Recovery yields were between 5% and 40%, as determined from cell counts. The method conserves cellular element contents to within 30% or better, as assessed by comparing C, N, P, Mg, Al, Ca, Ti, Mn, Fe, Ni, Cu, Zn, and Mo contents in Escherichia coli. Contamination by C, N, and P from chemicals used during the procedure was negligible. Na and K were not conserved, being likely exchanged through the cell membrane as cations during separation. V, Cr, and Co abundances could not be determined due to large (>100%) measurement uncertainties. We applied this method to measure elemental contents in extremophilic communities of Yellowstone National Park hot springs. The method was generally successful at separating cells from sediment, but does not discriminate between cells and detrital biological or noncellular material of similar density. This resulted in Al, Ti, Mn, and Fe contamination, which can be tracked using proxies such as metal:Al ratios. With these caveats, we present the first measurements, to our knowledge, of the elemental abundances of a chemosynthetic community. The communities have C:N ratios typical of aquatic microorganisms, are low in P, and their metal abundances vary between hot springs by orders of magnitude.
Reconstructing Early Neolithic Social and Economic Organization through Spatial Analysis at Ayn Abu Nukhayla, Southern Jordan
Authors: Henry Donald O. , Kadowaki Seiji , Bergin Sean M.
Published: July 2014

This study involves the high-resolution spatial analysis of a 9,500-year-old Early Neolithic site in an effort to reconstruct the social and economic organization of the settlement at household and community scales. We introduce an approach to distinguishing stratified occupational surfaces (floors) from intervening deposits (fills), to tracing the different formation processes associated with floors and fills, and to critically examining various factors (curation behaviors, palimpsests, and the Clarke Effect) that may have shaped house floor assemblages. The spatial analyses of behavioral residuals, features, and structures are then presented at intramural and intrasite scales, and the results are discussed as they relate to certain aspects of the social and economic organization of the community. These include family structure, control of resources, social differentiation, ritual participation, craft specialization, and gender-linked activities.
The Better Angels of their Nature: Declining Violence through Time Among Prehispanic Farmers of the Pueblo Southwest
Authors: Kohler Timothy A. , Ortman Scott G. , Grundtisch Katie E. , Fitzpatrick Carly M. , Cole Sarah M.
Published: July 2014

The central Mesa Verde and the northern Rio Grande regions housed two of the densest populations of prehispanic Pueblo peoples in the North American Southwest. We plot incidence of violent trauma on human bone through time in each region. Such violence peaked in the mid-A.D. 1100s in the central Mesa Verde, and in general was higher through time there than in the northern Rio Grande region. In the central Mesa Verde, but not in the northern Rio Grande, there is a tendency for violence to be greater in periods of low potential maize produccción per capita and high variance in maize produccción, though these structural tendencies were on occasion overridden by historical factors such as the expansion and demise of the Chacoan polity and the regional depopulation. Violence generally declined through time in the northern Rio Grande until the arrival of the Spanish, even as populations increased. We propose that this decline was due to the combination of increased social span of polities, the importance of inter-Pueblo sodalities, the nature of religious practice, “gentle commerce,“ and increased adherence to a set of nonviolent norms.
Social Network Analysis of Early Classic Hohokam Corporate Group Inequality
Authors: Pailes Matthew C.
Published: July 2014

Network analysis provides a unique approach for archaeologists to identify structural relationships between the emergent properties of social interactions and the trajectory of corporate groups. This article presents the results of a survey of architectural features and a network analysis of walkways between house clusters at the thirteenth-century Hohokam site of Cerro Prieto, located in the Tucson Basin, Arizona. Statistical measures suggest that nascent inequality was developing at this site, making it an excellent case study of the factors that led to the emergence of economic and social differentiation. Network analysis provides a means to explain how corporate groups were able to leverage social connections in their struggle for ascendance in these spheres of interaction. Regardless of the strategy of social ascendance, a simple increase in the opportunity to influence others appears to explain a large portion of differential corporate group success.
Spatiotemporal Analysis of Old World Diseases in North America, A.D. 1519–1807
Authors: Jones Eric E.
Published: July 2014

Over the last 25 years, a significant amount of archaeological and ethnohistoric research has produced data on Native American population trends after European contact. These include the timing and severity of depopulation and specific Old World diseases, allowing for meta-analytical research on a variety of topics. These data have been used in studies to explore the severity of depopulation, but the spatial and temporal patterns of diseases have been studied less. This research employs spatial analysis methods—Mantel tests and kriging—to study the relationship between the location and timing of Old World disease events on continental and regional scales, with the goal of examining how diseases spread over time and space. The results show that the timing of disease-related depopulation closely correlated with location, indicating that disease events clustered with regard to time and space. This strongly suggests that individual disease events impacted local populations and did not spread long distances (> 300 km) until the late seventeenth century. The analysis also reveals variations in the speed with which diseases spread. Interpreting the results with respect to pathogen, host, and environmental factors suggests that population distributions and landscape may have played significant roles in where and how fast diseases spread.
Heat Treatment, Ozarks Cherts, and Prehistoric Toolstone Use in Southwest Missouri
Authors: Byers David A. , Picka Craig , Ray Jack H.
Published: July 2014

Burlington and Jefferson City cherts often dominate Ozarks lithic assemblages, and this record contains ample evidence for the heat treatment of both. In this paper, we use a technological investment model to understand why prehistoric knappers may have invested in heat treatment at the Big Eddy Site in southwest Missouri. Tech investment models offer one way to evaluate the cost-benefit relationships of various technologies and, consequently, the conditions under which a manufacturing strategy might be adopted. We conduct a heat treatment experiment to measure the untreated utilities of the two materials, the approximate time needed to heat each, and the resultant gains in utility a knapper acquires by spending the time to do so. In the Big Eddy case, the tech investment model suggests that the two toolstones were heat-treated differentially in response to differences in utility gains and availability on the landscape.
A Critical Evaluation of Recent Gendered Publishing Trends in American Archaeology
Authors: Bardolph Dana N.
Published: July 2014

This paper explores the relationship between gender identity and patterns of authorship in peer-reviewed journals as a lens for examining gendered knowledge production and the current status and visibility of men and women in American archaeology. Drawing on feminist theory and the feminist critique of science, I examine how gender imbalance and a lack of diversity continue to affect the work that archaeologists produce. The evaluation of publishing trends serves as a means to investigate knowledge valuation/validation in archaeology and lends insight into the control over archaeological narratives. Analysis of publicacion rates from 1990–2013 in a number of prestigious archaeology research journals (including American Antiquity) as well as smaller-scale regional journals reveals that strong gender differences persist in one of the major ways that data are disseminated to the American archaeological community. I suggest that these patterns are likely a result of authorial behavior, rather than editorial or reviewer bias, and conclude with a discussion of future directions for practitioners to pursue research on gender equity in the discipline.
Redating the Mill Iron Site, Montana: A Reexamination of Goshen Complex Chronology
Authors: Waters Michael R. , Stafford Thomas W.
Published: July 2014

The Paleoindian Goshen complex occurs in the northern Plains and eastern Rocky Mountains. Since its identification, there has been much discussion about the chronological placement of the Goshen complex. This is especially true because diagnostic Goshen projectile points occur stratigraphically below Folsom artifacts at two sites, and early dates from the Mill Iron site, Montana, and the Hell Gap site, Wyoming, have suggested that this point type might be coeval with Clovis or the very earliest Folsom sites. This report presents new radiocarbon dates from the Mill Iron site, reviews Goshen chronology, and revises the age of the Goshen complex as 10,450 ± 15 to 10,175 ± 40 radiocarbon years B.P.
The Island Chumash and Exchange in the Santa Barbara Channel Region
Authors: Gill Kristina M. , Erlandson Jon M.
Published: July 2014

Fauvelle (2013) used experimental approaches to evaluate whether acorns were an important commodity traded from mainland groups to the Island Chumash. Consistent with a dearth of acorn remains found in island sites, he concluded that acorns were not a major export. We agree with this conclusion, but Fauvelle never adequately explains why acorns were not a major trade item and proposes that trade for high-quality asphaltum, supposedly unavailable on the islands, drove an intensification of Chumash social complexity. We believe the Island Chumash had abundant local plant foods, asphaltum, and other resources.
Acorns, Asphaltum, and Asymmetrical Exchange: Invisible Exports and the Political Economy of the Santa Barbara Channel
Authors: Fauvelle Mikael
Published: July 2014

Exciting new discoveries have forced us to reevaluate longstanding assumptions regarding the origins of social complexity in the area of the Santa Barbara Channel. Whereas previous models for the development of Chumash chiefdoms assumed that islands were terrestrially marginal environments, current data suggest islanders enjoyed a diversity of subsistence resources. Given these developments, it is time for us to reexamine the economic basis for exchange across the Santa Barbara Channel.
Yaklaşma iniş sistemlerinde ileri teknolojiler
Authors: Ataş Sefer , Koç Osman , Çiftçibaşi Mehmet Emre , Kilinç Mustafa , Altin Deniz , Özdemir Başak Gonca , Yeşilyurt Alper
Published: July 2014

Özet

21. yüzyılda dünyanın ulaştığı teknolojik seviye, yaklaşma iniş sistemleri konusunda yeni bir çağ başlatmıştır. Tüm dünyada sivil ve askeri hava araçlarının iniş ve kalkışlarında halen kullanılan Hassas Yaklaşma Radarı ve Aletli İniş Sistemi gibi sistemler, orta ve uzun vadede uydu sinyallerini kullanan yeni sistemlerle güncellenecektir. Söz konusu yeni sistemlerin geliştirilmesinde çevresel şartların etkilerini azaltarak sinyal kalitesini artıracak çeşitli yer kesimi ve hava aracı aviyonik birimlerinin ve ilgili algoritmaların geliştirilmesi gerekmektedir. Türkiye ve tüm dünya için yeni bir araştırma konusu olan söz konusu sistemlerde, mevcut ve gelecekteki uydu kümeleriyle birlikte çalışabilirlik önem arz etmektedir. Bu çalışmada uydu tabanlı yaklaşma iniş teknolojilerine genel bakışla birlikte sistemlere yönelik teknik bilgiler verilmiş, Uydu Tabanlı Destek Sistemi (UTDS) ve Yer Tabanlı Destek Sistemi (YTDS)’nin örnek uygulamalar ile birlikte askeri kullanımda sağladıkları operasyonel avantajlar detaylandırılmış, ileri teknolojilerin kullanıldığı yaklaşma türleri hakkında genel bilgiler verilmiş, İHA’larda UTDS/YTDS kullanımı ve otomatik kalkış ve iniş desteğinin önemi ile birlikte operasyonel kullanımı etkileyen faktörlere ve askeri ve sivil yaklaşma iniş sistemlerinin birlikte çalışabilirliğine yer verilerek Türkiye’nin gelecekte iyi bir konumda olması için yapılması gereken çalışmalar ve taslak UTDS/YTDS yol haritası sunulmuştur.
Global Case Fatality of Bacterial Meningitis During an 80-Year Period
Authors: van Ettekoven Cornelis N. , Liechti Fabian D. , Brouwer Matthijs C. , Bijlsma Merijn W. , van de Beek Diederik
Published: August 2024

Importance

The impact of vaccination, antibiotics, and anti-inflammatory treatment on pathogen distribution and outcome of bacterial meningitis over the past century is uncertain.

Objective

To describe worldwide pathogen distribution and case fatality ratios of community-acquired bacterial meningitis.

Data Sources

Google Scholar and MEDLINE were searched in January 2022 using the search terms bacterial meningitis and mortality.

Study Selection

Included studies reported at least 10 patients with bacterial meningitis and survival status. Studies that selected participants by a specific risk factor, had a mean observation period before 1940, or had more than 10% of patients with health care–associated meningitis, tuberculous meningitis, or missing outcome were excluded.

Data Extraction and Synthesis

Data were extracted by 1 author and verified by a second author. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Random-effects models stratified by age (ie, neonates, children, adults), Human Development Index (ie, low-income or high-income countries), and decade and meta-regression using the study period’s year as an estimator variable were used.

Main Outcome and Measure

Case fatality ratios of bacterial meningitis.

Results

This review included 371 studies performed in 108 countries from January 1, 1935, to December 31, 2019, describing 157 656 episodes. Of the 33 295 episodes for which the patients’ sex was reported, 13 452 (40%) occurred in females. Causative pathogens were reported in 104 598 episodes with Neisseria meningitidis in 26 344 (25%) episodes, Streptococcus pneumoniae in 26 035 (25%) episodes, Haemophilus influenzae in 22 722 (22%), other bacteria in 19 161 (18%) episodes, and unidentified pathogen in 10 336 (10%) episodes. The overall case fatality ratio was 18% (95% CI, 16%-19%), decreasing from 32% (95% CI, 24%-40%) before 1961 to 15% (95% CI, 12%-19%) after 2010. It was highest in meningitis caused by Listeria monocytogenes at 27% (95% CI, 24%-31%) and pneumococci at 24% (95% CI, 22%-26%), compared with meningitis caused by meningococci at 9% (95% CI, 8%-10%) or H influenzae at 11% (95% CI, 10%-13%). Meta-regression showed decreasing case fatality ratios overall and stratified by S pneumoniae, Escherichia coli, or Streptococcus agalactiae (P < .001).

Conclusions and Relevance

In this meta-analysis with meta-regression, declining case fatality ratios of community-acquired bacterial meningitis throughout the last century were observed, but a high burden of disease remained.
A novel TAp73‐inhibitory compound counteracts stemness features of glioblastoma stem cells
Authors: Villoch‐Fernandez Javier , Martínez‐García Nicole , Martín‐López Marta , Maeso‐Alonso Laura , López‐Ferreras Lorena , Vazquez‐Jimenez Alberto , Muñoz‐Hidalgo Lisandra , Garcia‐Romero Noemí , Sanchez Jose María , Fernandez Antonio , Ayuso‐Sacido Angel , Marques Margarita M. , Marin Maria C.
Published: August 2024

Glioblastoma (GB) is the most common and fatal type of primary malignant brain tumor for which effective therapeutics are still lacking. GB stem cells, with tumor‐initiating and self‐renewal capacity, are mostly responsible for GB malignancy, representing a crucial target for therapies. The TP73 gene, which is highly expressed in GB, gives rise to the TAp73 isoform, a pleiotropic protein that regulates neural stem cell biology; however, its role in cancer has been highly controversial. We inactivated TP73 in human GB stem cells and revealed that TAp73 is required for their stemness potential, acting as a regulator of the transcriptional stemness signatures, highlighting TAp73 as a possible therapeutic target. As proof of concept, we identified a novel natural compound with TAp73‐inhibitory capacity, which was highly effective against GB stem cells. The treatment reduced GB stem cell‐invasion capacity and stem features, at least in part by TAp73 repression. Our data are consistent with a novel paradigm in which hijacking of p73‐regulated neurodevelopmental programs, including neural stemness, might sustain tumor progression, pointing out TAp73 as a therapeutic strategy for GB.
HR research community stirred up after Zoom Yale comments
Authors: Knopf Alison
Published: August 2024

“Yikes.” That is the most common reaction from experts in the field to the revelations of a transcript, leaked by the Greater Harlem Coalition, of an interview between the organization's president, Shawn Hill, and researchers from Yale University. The transcript is of more than the interview; it is of a “hot mic” recording when the researchers — Ryan McNeil, Ph.D., director of Harm Reduction Research, Program in Addiction Medicine at Yale University and his colleague, Lisa Bonilla — apparently didn't realize they were being recorded and made disparaging remarks about Hill (ADAW quotes from the transcript below). Both researchers publicly apologized. However, a deeper concern is the possible subversion of research, in which a predetermined result is manipulated.
Changes in adolescents' nonmedical use of prescription drugs
Authors: Knopf Alison
Published: August 2024

A recent study has found that reductions in the nonmedical use of prescriptions by adolescents declined between 2009 and 2022 based partly on peer‐to‐peer diversions and perceived difficulty in obtaining such substances. While the results may be partially attributed to prescription guideline changes from the federal Centers for Disease Control and Prevention and to schools being closed during COVID, it's still essential to watch out for counterfeit pills, which can contain illicit and lethal fentanyl and other substances, according to authors of a research letter published in the July 24 online issue of JAMA. In “Adolescent Use, Diversion Sources, and Perceived Procurement Difficulty of Prescription Medications,” Sean Esteban McCabe, Ph.D., and colleagues discuss trends reported in the Monitoring the Future study (see ADAW https://onlinelibrary.wiley.com/doi/10.1002/adaw.34064), which showed a significant decrease in lifetime nonmedical use of prescriptions (23.66% of high school students in 2009 to 16% in 2022), as well as a decline in obtaining these medications from a friend (57.96% in 2009 to 26.87% in 2022) and in buying medications from a friend (44.35% in 2009 to 19.42% in 2022). The percentage of adolescents who said it would be impossible for them to obtain prescriptions for nonmedical use increased from 35.56% in 2009 to 48.96% in 2022. The problem — that lockdown of COVID from 2020 to 2022 and school closures making it difficult to even meet with friends — could affect these numbers, but the researchers expanding on the findings.
Sicherheit, Nachhaltigkeit und Digitalisierung im Fokus
Authors: Dietz Gregor , Gandert Etwina
Published: August 2024

Die Einführung der neuen Maschinenverordnung (EU) 2023/1230 löst die bisherige Maschinenrichtlinie 2006/42/EG ab und bringt Änderungen und Modernisierungen mit sich. Neben den gestiegenen Anforderungen an die Sicherheit und Funktionalität von Maschinen rückt auch das Thema Nachhaltigkeit in den Fokus. Besonders die neuen Recyclinganforderungen zielen darauf ab, den ökologischen Fußabdruck der Maschinenproduktion zu verringern und die Kreislaufwirtschaft zu fördern. Im Interview gibt Gregor Dietz, Marktmanager bei SEW‐Eurodrive in Bruchsal, Einblicke in die praktischen Auswirkungen der Verordnung.
Datenmanagement für die vorausschauende Wartung
Authors: Johnson Emily
Published: August 2024

Die Aufbereitung und Übertragung von Informationen vor dem Einsatz von predictive Maintenance (PdM)‐Lösungen sind entscheidend für eine erfolgreiche Implementierung. Die Datenaufbereitungs‐ und ‐übertragungsdienste von Drittanbietern können Zeit und Ressourcen sparen und gleichzeitig die Anlagenleistung und die betriebliche Effizienz verbessern.
Die passende Ventilstellungsüberwachung auswählen
Authors: Lumme Rainer
Published: August 2024

Hersteller von Ventilen haben eine breite Auswahl, wenn sie nach geeigneten Schaltgeräten für die Ventilstellungsüberwachung suchen. Es stehen unterschiedliche Bauformen von elektromechanischen Schaltgeräten und berührungslos wirkenden Sensoren zur Verfügung. Für explosionsgefährdete Bereiche, korrosive Umgebungen und für Tieftemperaturanwendungen gibt es geeignete Baureihen. In vielen Fällen, auch in Ex‐Zonen, ist der Einsatz von kabellosen Funkschaltgeräten vorteilhaft.
Anlagensicherheit gewährleisten
Authors: Teller‐Weyers Max
Published: August 2024

Die neue europäische Maschinenverordnung berücksichtigt nun auch Risiken, die durch die Nutzung von KI bspw. für Cobots entstehen. Ab 20. Januar 2027 ist die Übergangsfrist abgelaufen und Händler, Hersteller und Betreiber sollten darauf vorbereitet sein.
Understanding the Intrinsic Mechanism of High‐Performance Electrocatalytic Nitrogen Fixation by Heterogenization of Homonuclear Dual‐Atom Catalysts
Authors: Zhang Yuefei , Yang Yu , Zhang Yu , Liu Xuefei , Xiao Wenjun , Wang Degui , Wang Gang , Wang Zhen , Bi Jinshun , Liu Jincheng , Zhou Xun , Wang Wentao
Published: August 2024

A heteronuclear dual transition metal atom catalyst is a promising strategy to solve and relieve the increasing energy and environment crisis. However, the role of each atom still does not efficiently differentiate due to the high activity but low detectability of each transition metal in the synergistic catalytic process when considering the influence of heteronuclear induced atomic difference for each transition metal atom, thus seriously hindering intrinsic mechanism finding. Herein, we proposed coordinate environment vary induced heterogenization of homonuclear dual‐transition metal, which inherits the advantage of heteronuclear transition metal atom catalyst but also controls the variable of the two atoms to explore the underlying mechanism. Based on this proposal, employing density functional theory study and machine learning, 23 kinds of homonuclear transition metals are doping in four asymmetric C3N for heterogenization to evaluate the underlying catalytic mechanism. Our results demonstrate that five catalysts exhibit excellent catalytic performance with a low limiting potential of −0.28 to −0.48 V. In the meantime, a new mechanism, “capture–charge distribution–recapture–charge redistribution”, is developed for both side‐on and end‐on configuration. More importantly, the pronate site of the first hydrogenation is identified based on this mechanism. Our work not only initially makes a deep understanding of the transition dual metal‐based heteronuclear catalyst indirectly but also broadens the development of complicated homonuclear dual‐atom catalysts in the future.
Short‐term impact of vitamin K2 supplementation on biochemical parameters and lipoprotein fractions
Authors: Barna Milos , Dunovska Katerina , Cepova Jana , Werle Julia , Prusa Richard , Bjørklud Geir , Melichercik Pavel , Kizek Rene , Klapkova Eva
Published: August 2024

This study explored the short‐term effects of vitamin K2 (VK2) supplementation on biochemical parameters (vitamin D, vitamin E, vitamin A, alkaline phosphatase, calcium, phosphorus (P), magnesium, metallothionein, triglycerides, cholesterol, high‐density lipoprotein (HDL), low‐density lipoprotein (LDL), and lipoprotein fractions (albumin, HDL, very low‐density lipoprotein (VLDL), LDL, and chylomicrons). A short‐term experiment (24 h, six probands) was performed to track changes in VK2 levels after a single‐dose intake (360 µg/day). Liquid chromatography–tandem mass spectrometry was used to monitor vitamin K levels (menaquinone‐4 (MK‐4), menaquinone‐7 (MK‐7), and vitamin K1 [VK1]) with a limit of detection of 1.9 pg/mL for VK1 and 3.8 pg/mL for the two forms of VK2. Results showed that MK‐7 levels significantly increased within 2–6 h post‐administration and then gradually declined. MK‐4 levels were initially low, showing a slight increase, whereas VK1 levels rose initially and then decreased. Biochemical analyses indicated no significant changes in sodium, chloride, potassium, calcium, magnesium, albumin, or total protein levels. A transient increase in P was observed, peaking at 12 h before returning to baseline. Agarose gel electrophoresis of lipoprotein fractions revealed distinct chylomicron bands and variations in VLDL and HDL mobility, influenced by dietary lipids and VK2 supplementation. These findings suggest effective absorption and metabolism of MK‐7 with potential implications for bone metabolism and cardiovascular health.
Rhinovirus characteristics associated with viremia in childhood asthma
Authors: Lejeune Stéphanie B. , Deschildre Antoine , Morel Constance L. , Béghin Laurent R. , Drumez Elodie , Pichavant Muriel , Gosset Philippe , Engelmann Ilka ,   VIRASTHMA2 Study Group
Published: August 2024

Although rhinoviruses play a major role in exacerbations of childhood asthma, the presence of rhinovirus (RV) RNA in plasma, referred to as viremia, has been investigated in a few studies. The aim of the study was to investigate the presence of rhinovirus viremia at the time of asthma exacerbation and to describe the molecular characteristics of rhinoviruses associated with viremia. We conducted an observational, prospective, multicenter study in eight pediatric hospitals (VIRASTHMA2). Preschool‐aged recurrent wheezers (1–5 years) hospitalized for a severe exacerbation were included. Reverse‐transcription polymerase chain reaction (RT‐PCR) and molecular typing for RV/enteroviruses (EV) were performed on nasal swabs and plasma. Plasma specimens were available for 105 children with positive RT‐PCR for RV/EV in respiratory specimens. Thirty‐six (34.3%) had positive viremia. In plasma, 28 (82.4%) of the typable specimens were RV‐C, five (14.7%) were EV‐D68, and one was RV‐A (2.9%). In all cases, the RV/EV type was identical in the plasma and respiratory specimens. In conclusion, RV/EV viremia is frequent in severe exacerbations of preschool recurrent wheezers, particularly in RV‐C infections.