bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EVOLUTION OF METALLICITY AND METALLICITY GRADIENTS FROM z = 2.7 TO 0.6 WITH KMOS3D
Authors: Wuyts Eva , Wisnioski Emily , Fossati Matteo , Schreiber Natascha M. Förster , Genzel Reinhard , Davies Ric , Mendel J. Trevor , Naab Thorsten , Röttgers Bernhard , Wilman David J. , Wuyts Stijn , Bandara Kaushala , Beifiori Alessandra , Belli Sirio , Bender Ralf , Brammer Gabriel B. , Burkert Andreas , Chan Jeffrey , Galametz Audrey , Kulkarni Sandesh K. , Lang Philipp , Lutz Dieter , Momcheva Ivelina G. , Nelson Erica J. , Rosario David , Saglia Roberto P. , Seitz Stella , Tacconi Linda J. , Tadaki Ken-ichi , Übler Hannah , Dokkum Pieter van
Published: August 2016

We present measurements of the [N ii]/Hα ratio as a probe of gas-phase oxygen abundance for a sample of 419 star-forming galaxies at z = 0.6–2.7 from the KMOS3D near-IR multi-integral field unit (IFU) survey. The mass–metallicity relation (MZR) is determined consistently with the same sample selection, metallicity tracer, and methodology over the wide redshift range probed by the survey. We find good agreement with long-slit surveys in the literature, except for the low-mass slope of the relation at

, where this sample is less biased than previous samples based on optical spectroscopic redshifts. In this regime we measure a steeper slope than some literature results. Excluding the contribution from active galactic nuclei from the MZR reduces sensitivity at the high-mass end, but produces otherwise consistent results. There is no significant dependence of the [N ii]/Hα ratio on star formation rate at fixed redshift and stellar mass. The IFU data allow spatially resolved measurements of [N ii]/Hα, from which we can infer abundance gradients for 180 galaxies, thus tripling the current sample in the literature. The observed gradients are on average flat, with only 15 gradients statistically offset from zero at

. We have modeled the effect of beam smearing, assuming a smooth intrinsic radial gradient and known seeing, inclination, and effective radius for each galaxy. Our seeing-limited observations can recover up to 70% of the intrinsic gradient for the largest, face-on disks, but only 30% for the smaller, more inclined galaxies. We do not find significant trends between observed or corrected gradients and any stellar population, dynamical, or structural galaxy parameters, mostly in agreement with existing studies with much smaller sample sizes. In cosmological simulations, strong feedback is generally required to produce flat gradients at high redshift.
THE RELATION BETWEEN STELLAR AND DYNAMICAL SURFACE DENSITIES IN THE CENTRAL REGIONS OF DISK GALAXIES
Authors: Lelli Federico , McGaugh Stacy S. , Schombert James M. , Pawlowski Marcel S.
Published: August 2016

We use the Spitzer Photometry and Accurate Rotation Curves (SPARC) database to study the relation between the central surface density of stars

Σ

⋆

(
0
)

and dynamical mass

Σ

dyn

(
0
)

in 135 disk galaxies (S0 to dIrr). We find that

Σ

dyn

(
0
)

correlates tightly with

Σ

⋆

(
0
)

over 4 dex. This central density relation can be described by a double power law. High surface brightness galaxies are consistent with a 1:1 relation, suggesting that they are self-gravitating and baryon dominated in the inner parts. Low surface brightness (LSB) galaxies systematically deviate from the 1:1 line, indicating that the dark matter contribution progressively increases but remains tightly coupled to the stellar one. The observed scatter is small (∼0.2 dex) and largely driven by observational uncertainties. The residuals show no correlations with other galaxy properties like stellar mass, size, or gas fraction.
Cytomegalovirus Infection during Pregnancy and Its Impact on the Intrauterine Fetal Development â€“ Case Report
Authors: Angelova Mariya Angelova , Kovachev Emil , Todorov Nikolai
Published: August 2016

AIM: The aim of this publication is to present a case of CMV infection during pregnancy, with clinical manifestations of the development of microcephaly and simultaneous dilatation of the 3rd and 4th brain ventricle at 23 weeks gestation. This article discusses the role of ultrasound screening in the second trimester of pregnancy.CASE PRESENTATION: We present the case of a 25-year-old woman with the initials S.K. in her second pregnancy that came to our antenatal Consulting Centre. The first screening for blood count, blood group, biochemistry and serology showed results within the reference range. The patient came for a second comprehensive biochemical screening at 17 â€“ 18 weeks gestation. The results showed the low genetic risk of congenital anomalies. Fetal morphology of the fetus was normal. S.K. came again for consultation at 22 weeks gestation in connection with the admittance of her first 3-year-old child to the hospital because of pneumonia. Serological tests of the child had shown elevated CMV titer - specific IgM. Then we made new serological tests of the patient and the results have shown that the patient was most likely infected by CMV primarily in the first trimester of pregnancy. After consulting about the risk of transmission of CMV to the fetus, the woman chose monthly ultrasound scans and refused amniocentesis. At 36 weeks gestation, in addition to the microcephaly already established, enlargement of the IV brain ventricle at the expense of underdevelopment of the cerebellum was noticed. Also, 2nd to 3rd stage of placenta maturity and low quantity of amniotic fluid was established. A male fetus of weight 2,890 g and height 50 cm was delivered.Â Â  The fetus was with skin petechiae and hepatosplenomegaly. Neurological examination showed no abnormalities.CONCLUSIONS: In the described case the time interval between infection and ultrasonic manifestations is more than 17 weeks. The long interval between infection and occurrence of ultrasound markers can be a good prediction sign, as it may reflect less aggressive viral infection than present in cases where similar ultrasound findings were obtained shortly after infection of the mother.
Bone Reduction Clamp to Gain Length in Repairing Chronic Achilles Tendon Ruptures
Authors: Buckley Patrick S. , Pedowitz David I.
Published: August 2016

Chronic Achilles tendon ruptures occur after an unrecognized, untreated, or misdiagnosed acute Achilles tendon rupture and present a potentially debilitating injury for the patient. Various techniques have been described to reconstruct the Achilles tendon after chronic ruptures. The technique chosen depends on the length of tendon defect that is present after debridement. If the tendon gap is greater than 3 cm, additional techniques are generally used, as direct repair is often not possible. The authors present a novel intraoperative technique using pointed reduction clamps to gain and maintain length of the Achilles tendon to decrease the gap between ends of the Achilles tendon and allow for end-to-end repair when it may have otherwise not been possible. [
Orthopedics.
2016; 39(6):e1223–e1225.]
Influence of Pachymetry and Intraocular Pressure on Dynamic Corneal Response Parameters in Healthy Patients
Authors: Vinciguerra Riccardo , Elsheikh Ahmed , Roberts Cynthia J. , Ambrósio Renato , Kang David Sung Yong , Lopes Bernardo T. , Morenghi Emanuela , Azzolini Claudio , Vinciguerra Paolo
Published: August 2016

PURPOSE:

To evaluate the influence of pachymetry, age, and intraocular pressure in normal patients and to provide normative values for all dynamic corneal response parameters (DCRs) provided by dynamic Scheimpflug analysis.

METHODS:

Seven hundred five healthy patients were included in this multicenter retrospective study. The biomechanical response data were analyzed to obtain normative values with their dependence on corrected and clinically validated intraocular pressure estimates developed using the finite element method (bIOP), central corneal thickness (CCT), and age, and to evaluate the influence of bIOP, CCT, and age.

RESULTS:

The results showed that all DCRs were correlated with bIOP except deflection amplitude (DefA) ratio, highest concavity (HC) radius, and inverse concave radius. The analysis of the relationship of DCRs with CCT indicated that HC radius, inverse concave radius, deformation amplitude (DA) ratio, and DefA ratio were correlated with CCT (rho values of 0.343, −0.407, −0.444, and −0.406, respectively). The age group subanalysis revealed that primarily whole eye movement followed by DA ratio and inverse concave radius were the parameters that were most influenced by age. Finally, custom software was created to compare normative values to imported examinations.

CONCLUSIONS:

HC radius, inverse concave radius, DA ratio, and DefA ratio were shown to be suitable parameters to evaluate in vivo corneal biomechanics due to their independence from IOP and their correlation with pachymetry and age. The creation of normative values allows the interpretation of an abnormal examination without the need to match every case with another normal patient matched for CCT and IOP.

[
J Refract Surg
. 2016;32(8):550–561.]
Comparison of Simulated Keratometric Changes Following Wavefront-Guided and Wavefront-Optimized Myopic Photorefractive Keratectomy
Authors: Lee Wen-Shin , Manche Edward E.
Published: August 2016

PURPOSE:

To determine the relationship between change in simulated keratometry and corrected refractive error in both wavefront-guided and wavefront-optimized myopic photorefractive keratectomy (PRK), and to determine whether there is a difference in this relationship between these two ablation profiles.

METHODS:

Sixty-eight patients received wavefront-guided PRK in one eye and wavefront-optimized PRK in the contralateral eye. The changes in simulated keratometry and corresponding refractive changes for both were determined at 1 year postoperatively. Linear regression was employed to calculate the slope of change in simulated keratometry (ΔK) for change in refractive error (ΔSE) for both wavefront-guided and wavefront-optimized PRK and compared. The mean ratio ΔK/ΔSE was also calculated for both wavefront-guided and wavefront-optimized PRK and compared.

RESULTS:

There was no significant difference in the ratio of ΔK to ΔSE between wavefront-optimized and wavefront-guided PRK by both linear regression modeling and comparison of the mean ratio ΔK/ΔSE. Linear regression modeling revealed that the ratio of ΔK/ΔSE was greater for small amounts of change in refractive error and smaller for large amounts of change in refractive error. This trend was only statistically significant for the wavefront-optimized group when comparing the means of the ratio ΔK/ΔSE (
P
= .0287).

CONCLUSIONS:

The change in corneal curvature induced for a given degree of refractive correction was similar for both wavefront-optimized and wavefront-guided PRK. For both, a proportionally smaller amount of corneal flattening was required for larger degrees of refractive correction compared to smaller degrees.

[
J Refract Surg
. 2016;32(8):542–548.]
Multiple Attribute Group Decision Analysis for Intuitionistic Triangular and Trapezoidal Fuzzy Numbers
Authors: John Robinson P.
Published: August 2016

Solving Multiple Attribute Group Decision Making (MAGDM) problems has become one of the most important researches in recent days. In situations where the information or the data is of the form of an Intuitionistic Triangular Fuzzy Number (ITrFN) or Intuitionistic Trapezoidal Fuzzy Number (ITzFN), a new distance function is defined for ranking the alternatives in the decision making process. After processing the decision information through a sequence of arithmetic aggregation operators, namely, the Intuitionistic Triangular Fuzzy Weighted Arithmetic Averaging (ITrFWAA), Intuitionistic Triangular Fuzzy Ordered Weighted Averaging (ITrFOWA) operator and the Intuitionistic Triangular Fuzzy Hybrid Aggregation (ITrFHA) operator, the proposed distance function is utilized to rank the best alternative. A model is proposed to solve MAGDM problems using the developed distance formula defined for ITrFNs. Numerical illustration is provided and comparisons are made with some of the existing MAGDM models and ranking procedures.
An Improved Hybrid Model for Order Quantity Allocation and Supplier Risk Exposure
Authors: Ng Peh Sang , Zhang Feng
Published: August 2016

This paper investigates the risk exposure arising from the supplier evaluation criteria of cost, quality, delivery, and flexibility. An integrated method of Fuzzy Decision Making Trial and Evaluation Laboratory (FDEMATEL) and Fuzzy Analytical Network Process (FANP), which is able to address interaction and feedback effects between the criteria and subjectivity in the decision rating, is used to generate the importance weights of the objectives for a network relationship problem. Different weights of the objectives are then incorporated into a Fuzzy Multi-Objective Programming (FMOP) model for determining the optimal order quantity allocated to the suppliers. The proposed method provides a more realistic decision making scenario by considering different importance weights of criteria from individual priority. Therefore, it provides a practical method to solve the real world problems. The validity of the proposed method is illustrated by a case study from a trading company.
A Structured Inquiry into a Digital Story
Authors: Penttilä Johanna , Kallunki Veera , Niemi Hannele M. , Multisilta Jari
Published: August 2016

Schools have been islands isolated from mobile technologies for a long time. In Finland, schools are investing in mobile technologies with the aim of providing a tablet for each student. This trend enables classes to adopt practices where students not only use ready-made learning materials but generate content as well. This paper aims to investigate student-generated digital stories as learning artefacts through a case example from two chemistry classes in a primary school. After introducing a method of creating digital stories from a structured inquiry, the paper presents an in-depth analysis of a specific type of story, its construction and conceptual learning outcomes related to the story's topic (i.e., chemical reaction). The results indicate that storytelling based on a structured inquiry is suited for novice science learners. In the future, teaching visual communication skills and story scripting to students should be emphasised to make the stories more sophisticated.
An Agile Architecture for a Legacy Enterprise IT System
Authors: Pang Chung-Yeung
Published: August 2016

Back in the 1970s, applications mainly comprised programs written in COBOL. Many of these applications are still in operation. To meet new business demands, new applications that have to collaborate with existing programs need to be developed. It is possible to have an agile software architecture that enables easy development, extension and maintenance in COBOL. Such an architecture, and the agile development process, are presented in this article. The architectural design is a combination of the layered, component-based and service-oriented architectural patterns. It also includes features such as the centralized control of the business process, plug-and-play autonomous COBOL modules and context container for storing state data. A model-driven approach is used in the agile development process. Application models include UML class diagrams, state charts and activity diagrams from which various software artefacts and COBOL codes are generated. The architecture and development approaches were first introduced in 2004 and have been successfully applied to 13 applications since then.
Expanding Learning Opportunities for Graduate Students with HyFlex Course Design
Authors: Abdelmalak Mariam Mouse Matta , Parra Julia Lynn
Published: August 2016

The purpose of this study was to explore students' perspectives regarding HyFlex course design. The main feature of HyFlex is blending synchronous online student attendance and face-to-face student attendance (hybrid) in a single course and allowing students to choose when and how they attend (flexible). The course in this study implemented HyFlex principles to expand learning opportunities of adult graduate students in a higher education setting. The data collection sources included interviews of six graduate students, class observations, recordings of class meetings, students' course work, and relevant online course artifacts. Results indicated that participants perceived HyFlex to be a good way to accommodate student needs and their life circumstances, increase student access to course content and instruction, differentiate instruction to meet adult students' different learning styles and strategies, and give students a sense of control over their learning.
Information Technology Progress Indicators
Authors: Amer T. S. , Johnson Todd L.
Published: August 2016

Users of information technology (IT) often encounter “progress indicators” during their interactions. These graphics appear on screen as a user waits for a task to complete and are designed to inform the user of the progress made as the task moves toward completion. This study employs theoretical models from research on human experiences in waiting to develop hypotheses related to the design of one type of progress indicator: the “stalling progress bar.” That is, a progress bar that moves consistently during most of the computing process but then stalls for an indeterminate period before completing. Data from one experiment indicates that participants preferred a progress bar that moves consistently to a stalling progress bar, and judged the process duration to be shorter with the linear progress bar. Data from a second experiment indicates that displaying an explanatory message with a stalling progress bar enhances participant's perception about the stalling bar.
Impact of Cross-Channel Strategy on Brand's Commitment
Authors: Dutot Vincent
Published: August 2016

The luxury sector as a whole is experiencing a delay in digitalization, both in store and online, while customers are more and more attracted by digital experiences. Strategies such as driving online customers into shops, or using the web to complete store information are increasing and integrated in what we call cross-channel strategies. This research aims to understand the determinants and impacts of cross-channel experience on brand's attachment, in an affordable luxury context. Based on a qualitative analysis (individual interviews with customers and experts) carried by the case of the brand Comptoir des Cotonniers; the results show the role of each channel in the purchasing decision. Moreover, it demonstrates the synergy between offline and online channels, as well as the development of experiential elements (online and in store) appear to be the key elements of brand's commitment.
Responsibility and Skills Requirements for Entry Level Analytics Professionals
Authors: Luo Wenhong
Published: August 2016

As companies continue to incorporate analytics into all aspects of their business, there is a growing demand for analytics professionals with the right mix of skills and experiences. This study examines the responsibilities and skill requirements for entry level analytics professionals by analyzing the job ads posted on three major job sites during a six-month period. The author's results show that companies expect entry level analytics professionals to work with a team and to contribute in early stages of analytics work. In terms of technical capabilities, companies stress the general abilities to work with data, including the use of database and spreadsheet tools for organizing, analyzing, and reporting data. Surprisingly, data mining, optimization, and other advanced analytical methods are not often listed as desired skills for entry level positions. The study can help universities and institutions in curriculum design as well as in working with the industry to define and guide the development of skill requirements.
An Empirical Investigation of Decision Making in IT-Related Dilemmas
Authors: Zhang Chen , Simon Judith C. , Lee Euntae “Ted”
Published: August 2016

Given the rising IT security and privacy concerns, organizations are increasing their spending to strengthen technical protections. However, the problem of individuals wanting to find ways to gain access to IT resources improperly remains. To gain a better understanding of individuals' intentions to behave unacceptably in IT-related situations with conflicting interests, an information focus approach is adopted and the effects of information regarding possible consequences on their intentions is empirically investigated through a vignette-based survey. The findings not only confirm the deterrent role of information about possible negative consequence in these situations but also reveal that such influence is greater in situations involving software products than in situations involving data and for individuals with a higher level of fundamental concern for the welfare of others. Furthermore, this study reveals how the influence of consequence information on the intention to perform an unacceptable behavior may be dependent on individual factors and situational factors.
Architectural history research - a plea for "place-making"
Authors: Emmanuel Rohinton
Published: August 2016

No abstract available
lck-Driven Cre Expression Alters T Cell Development in the Thymus and the Frequencies and Functions of Peripheral T Cell Subsets
Authors: Carow Berit , Gao Yu , Coquet Jonathan , Reilly Marie , Rottenberg Martin E.
Published: August 2016

Conditional gene targeting using the bacteriophage-derived Cre recombinase is widely applied for functional gene studies in mice. Mice transgenic for Cre under the control of the lck gene promoter are used to study the role of loxP-targeted genes in T cell development and function. In this article, we show a striking 65% reduction in cellularity, preferential development of γδ versus αβ T cells, and increased expression of IL-7R in the thymus of mice expressing Cre under the proximal lck promoter (lck-cre+ mice). The transition from CD4/CD8 double-negative to double-positive cells was blocked, and lck-cre+ double-positive cells were more prone to apoptosis and showed higher levels of Cre expression. Importantly, numbers of naive T cells were reduced in spleens and lymph nodes of lck-cre+ mice. In contrast, frequencies of γδ T cells, CD44+CD62L− effector T cells, and Foxp3+ regulatory T cells were elevated, as was the frequency of IFN-γ–secreting CD4+ and CD8+ T cells. A literature survey of 332 articles that used lck-cre+ mice for deletion of floxed genes indicated that results are statistically influenced by the control used (lck-cre+ or lck-cre−), more frequently resembling the lck-cre+ phenotype described in this article if lck-cre− controls were used. Altogether, care should be taken when interpreting published results and to properly control targeted gene deletions using the lck-cre+ strain.
Supersuppression: Reservoir Competency and Timing of Mosquito Host Shifts Combine to Reduce Spillover of West Nile Virus
Authors: Levine Rebecca S. , Mead Daniel G. , Hamer Gabriel L. , Brosi Berry J. , Hedeen David L. , Hedeen Meghan W. , McMillan Joseph R. , Bisanzio Donal , Kitron Uriel D.
Published: August 2016

In the eastern United States, human cases of West Nile virus (WNV) result from spillover from urban epizootic transmission between passerine birds and Culex mosquitoes. In Atlanta, GA, substantial WNV presence in hosts and vectors has not resulted in the human disease burden observed in cities with similar infection pressure. Our study goal was to investigate extrinsic ecological conditions that potentially contribute to these reduced transmission rates. We conducted WNV surveillance among hosts and vectors in urban Atlanta and recorded an overall avian seroprevalence of nearly 30%, which was significantly higher among northern cardinals, blue jays, and members of the mimid family, and notably low among American robins. Examination of temporal Culex feeding patterns showed a marked feeding shift from American robins in the early season to northern cardinals in the late season. We therefore rule out American robins as superspreaders in the Atlanta area and suggest instead that northern cardinals and mimids act as WNV “supersuppressor” species, which slow WNV transmission by drawing many infectious bites during the critical virus amplification period, yet failing to amplify transmission due to low host competencies. Of particular interest, urban forest patches provide spillover protection by increasing the WNV amplification fraction on supersuppressor species.
NUTRIENTS AND CARBON DIOXIDE IN THE COLUMBIA RIVER1,2
Authors: Park P. Kilho , Catalfomo Magdalena , Webster George R. , Reid Barry H.
Published: August 2016

During 1966, 1.8 × 1014 liters of water; 8.3 × 107, 2.1 × 109, and 2.7 × 1010 moles of phosphate, nitrate, and reactive silicate; 1.9 × 1011 equivalents of alkalinity; and 1.9 × 1011 moles of total carbon dioxide passed through Clatskanie, 87 km above the mouth of the Columbia River into the Astoria estuary and the Pacific Ocean. Along the main stream, phosphate, nitrate, and silicate concentrations show a definite seasonal change; their maxima occur in winter and minima in summer. On‐stream primary production greatly affects the formation of the summer minima. At Clatskanie, the nitrate: phosphate ratio is 3:1 during summer months and over 19:1 at other seasons.

Bicarbonate ion is the major dissolved carbon dioxide species in the entire Columbia River system, where water pH measured at 20C ranges from 6.63 to 8.68. The major portion of the river system is undersaturated with respect to calcite solubility. Along the main stream, the river is supersaturated with respect to the atmospheric carbon dioxide pressure of 320 ppm.
Two sediment trap designs for use in small rivers and streams1
Authors: Welton J. S. , Ladle M.
Published: August 2016

Two sediment traps designed for

use in riverine gravels to assess rates, size, and gross quantities of sedimenting material and each having a collecting area of 40 cm2 are small, easy to construct and to handle. The results of the two types of traps used in the gravel bed of a recirculating channel are compared and recovery efficiencies are given based on laboratory experiments.
Nuisance phytoplankton blooms in coastal, estuarine, and inland waters1
Authors: Paerl Hans W.
Published: August 2016

Multiple interacting physical, chemical, and biotic factors, in proper combination, lead to the development and persistence of nuisance algal blooms. Upon examining combinations of environmental conditions most likely to elicit nuisance blooms, commonalities and analog situations become more apparent among coastal marine (dinoflagellate‐dominated), estuarine (dinoflagellate‐ and cyanobacteria‐dominated), and freshwater (cyanobacteria‐dominated) ecosystems. A combination of the following hydrological, chemical, and biotic factors will most likely lead to bloom‐sensitive waters: a horizontally distinct water mass; a vertically stratified water column; warm weather conditions, as typified by dry monsoon tropical climates and summer seasons in temperate zones; high incident photosynthetically active radiation (PAR); enhanced allochthonous organic matter loading (both as DOC and POC); enhanced allochthonous inorganic nutrient loading (nitrogen and/or phosphorus); adequate availability of essential metals, supplied by terrigenous inputs or upwelling; underlying sediments physically and nutritionally suitable as “seed beds” for resting cysts and akinetes; algal‐bacterial synergism, which exhibits positive impacts on phycosphere nutrient cycling; algal‐micrograzer (protists and rotifers) synergism, which also enhances nutrient cycling without consumption of filamentous and colonial nuisance taxa; and selective (for non‐nuisance taxa) activities of macrograzers (crustacean zooplankton, larval fish).

Nuisance bloom taxa share numerous additional physiological and ecological characteristics, including limited heterotrophic capabilities, high degrees of motility, and toxicity. Given such a set of commonalities, it would appear useful and timely to identify and address generally applicable criteria for deeming a water body “bloom sensitive” and to incorporate such criteria into the design of water quality management strategies applicable to both coastal marine and freshwater habitats.
Ecological principles affecting community structure and secondary production by zooplankton in marine and freshwater environments1
Authors: Lehman John T.
Published: August 2016

The production dynamics of zooplankton have been studied within two alternative conceptual frameworks. Some workers have emphasized the species composition of communities and the reproductive success of individual species, whereas others have studied the flow of nutrients and energy among ecosystem components. The reduced phylogenetic diversity of lake plankton compared with marine systems has favored the development of species‐based community ecology by limnologists. Theories that promote size structure as the salient community feature have been pioneered in marine systems and sometimes adopted for freshwater work. Empirical trends in physiological processes with organism size permit some rates to be estimated from size structure alone. With few exceptions, however, coefficients derived from log‐transformed regression equations have been applied uncritically in models, and little regard has been given to the large estimation errors involved. Metrics that are based on differences between physiological processes, rather than absolute rates of individual processes, are important ecologically. Threshold food concentration is an example: it measures the relative performance of food acquisition ability compared to acquisition and maintenance costs. These integrative properties do not vary strictly with organism size and they illustrate the fact that biological entities can develop many alternative solutions to the problems they face. Such results imply that whenever resource exploitation influences community composition, organism‐specific adaptations will prove more predictive than size structure.
Comparative ecology of the macrofauna of freshwater and marine muds1
Authors: Lopez Glenn R.
Published: August 2016

There are many striking similarities between the benthic macrofauna inhabiting marine and lacustrine sediments. Most of the same trophic/functional groups are well represented in both habitats. There is no obvious difference between the types of particulate food sources available for microphagous animals. Temperate lakes and neritic environments support a similar standing stock of macrofauna, which is a function of similar detrital input to the benthos. There is no characteristic difference in P : B ratios between marine and freshwater macrobenthos. Predation and competition have similar important effects on community structure. Likewise, community succession appears to follow the same pattern.

There are certain differences between marine and freshwater macrobenthos, however, that appear to relate to fundamental habitat differences. The major difference is that low salinity and the closed, ephemeral nature of most lakes have resulted in little taxonomic similarity between the two faunas. Tentaculate deposit feeders are found only in marine sediments, and interstitial suspension feeders are common only in freshwater muds. The ability to use dissolved organic matter is well developed only in marine animals, which is a consequence of the osmotic problems faced by freshwater animals. The ability of many limnetic species to survive prolonged anoxia relates to the lack of tidal mixing in lakes.
Accounting for effort when comparing tropical fisheries in lakes, river‐floodplains, and lagoons
Authors: Bayley Peter B.
Published: August 2016

Data from 59 tropical fisheries which were artisanal and multispecies in character indicated that fishing effort was a major determinant of yield. Effort was defined as number of full‐ and part‐time fishermen.

The largest subset, which comprised 31 African lake fisheries, conformed to a function related to the Schaefer model. Data from different lakes were thus treated as samples from a hypothetical multispecies fishery. The model explained 75% of the variance in log(yield). The residuals were correlated (P < 0.05) with log(morphoedaphic index). The effort model and the morphoedaphic index jointly explained 80% of the variance in log(yield). A function to account for the nonlinear effect of fishing effort was proposed for sets of fisheries conforming to the model.

Data from river‐floodplain and lagoon fisheries were very similar and were best described by the same effort model. Differences in the model parameters for these fisheries compared to those of lakes suggested differences in effective effort.

A “precision improvement index” was proposed to compare the predictive value of models with different predictors and transformations. A comparison of the predictability of yields revealed that, despite variation in socioeconomics, commercialization, and biological productivity between fisheries, this crude effort measurement was more important than indices of productivity for these sets of fisheries.

Future progress in predicting and understanding fisheries yields depends on the synchronized collection of variables that relate to the fishery and to biological productivity in numerous comparable systems.
Diagenesis of magnetic minerals in the recent sediments of a eutrophic lake
Authors: Anderson N. J. , Rippey B.
Published: August 2016

Magnetic mineral assemblages in lake sediments are usually interpreted as reflecting changing catchment erosion. Magnetic and chemical assemblages in a small eutrophic lake (Lough Augher, Northern Ireland) suggest diagenetic dissolution of fine‐grained magnetite, however, probably as a result of changing redox conditions associated with eutrophication. Water‐column results show internal cycling of Mn and Fe from the sediments into the anoxic hypolimnion. Calculations suggest that late‐summer hypolimnetic Fe concentrations are controlled by formation of authigenic vivianite; sedimentary pore‐water concentrations of total soluble Fe and P suggest a similar process in the sediments. The loss of Mn from the lake by diffusion from the sediment and washout at overturn is indicated by Mn budget calculations and by a marked decrease in its sedimentary concentration, reflecting onset of eutrophication as indicated by diatom biostratigraphy. The changes in the sediment Mn profile are coincident with, and in some cases identical to, changes in several magnetic parameters. The changes in magnetic stratigraphy suggest a coarsening of the magnetic grain size and reduction in the total concentration; agreement with chemical profiles indicative of changing redox suggest that this coarsening results from dissolution of fine‐grained magnetite. Catchment stability, together with other stratigraphic profiles of eutrophication and changing redox, supports the conclusion that the magnetic profiles are reflecting in situ diagenetic changes rather than altered catchment processes. With the data available it is not possible to identify the actual dissolution process involved or to determine whether it is chemically or bacterially controlled.
Dark production of H2O2 in the Sargasso Sea
Authors: Palenik B. , Morel F. M. M.
Published: August 2016

Hydrogen peroxide is introduced into the marine environment by wet and dry deposition and is produced there by photochemical reactions. Dark production, particularly by the biota, has not been demonstrated in situ. To investigate dark H2O2 production, we adapted a method of measuring H2O2 for use in the field. The method uses the enzyme‐catalyzed oxidation by H2O2 of hydroxyphenylpropionic acid to a fluorescent dimer; its detection limit is about 3 nM. Results of a field study in the Sargasso Sea (32°N, 62°W) confirmed several general characteristics of H2O2 distributions—a surface maximum and a diel cycle in surface waters. Data from the Sargasso Sea also demonstrated that dark, probably biological, production was occurring at significant rates at depths of 40–60 m.
Computerized tomography and image analysis: A tool for examining the skeletal characteristics of reef‐building organisms
Authors: Vago R. , Shai Y. , Ben‐Zion M. , Duhinsky Z. , Achituv Y.
Published: August 2016

Samples of the “bladed” morphotypes of the hydrocoral Millepora dichotoma were examined with a two‐stage computerized technique. The samples were analyzed by computerized tomography, and the resulting photographs were processed by computerized image analysis. The results disclosed skeletal growth modifications that occurred during the life history of the specimens. Within the present skeletal form we were able to reveal a former, delicate branching phase hidden in the extant skeleton. A high proportion of the bladed morphotypes was found to be infested by the coral‐inhabiting barnacle Savignium milleporum. The barnacles were embedded in the host skeleton, enhancing skeletal deformation.
Aquatic metabolism in the Everglades: Dominance of water column heterotrophy
Authors: Hagerthey Scot E. , Cole Jonathan J. , Kilbane Deborah
Published: August 2016

Using high‐frequency measurements of free water dissolved oxygen (O2), we assessed gross primary production (GPP), respiration (R), and net aquatic production (NAP) in the shallow‐water Everglades peatland between 1996 and 2005. We distinguish NAP from net ecosystem production since the boundary for shallow aquatic ecosystems may include aboveground GPP of wetland biota. Metabolism was estimated for 68 sites distributed among nine habitats and yielded 1085 5‐d deployments or 5425 site‐days. Habitats differed in vegetation composition, trophic status, and hydrology. Systemwide O2 averaged 3.8 ± 2.2 mg L−1 (mean ± SD), or 49% ± 30% of atmospheric saturation. GPP, R, and NAP averaged 103 ± 76, 220 ± 79, and −117 ± 65 mmol O2 m−2 d−1, respectively. Metabolism was greater during the summer‐wet season when greater irradiance, temperature, and material flux stimulate primary production and decomposition. Paradoxically, GPP was inversely related to total phosphorus (TP), with oligotrophic (TP < 7 mg L−1) open‐water habitats dominated by periphyton having the highest and eutrophic (TP > 35 mg L−1) habitats with dense emergent macrophytes the lowest rates. R was greatest for moderately enriched (TP = 15 mg L−1) open‐water habitats with floating macrophytes. The prevalence of net heterotrophy, 96% of the 1085 NAP estimates, reveals the importance of aboveground biota in regulating aquatic metabolism and O2 dynamics in shallow ecosystems. R is not only regulated by the influx of aboveground autochthonous carbon but also by aquatic GPP. Carbon turnover is greater in habitats where O2 production by aquatic vegetation enables aerobic respiration. Conversely, water‐column GPP is suppressed by dense emergent macrophytes, which limits O2 availability, favors anaerobic respiration, and reduces carbon turnover.
Contribution of mycosporine‐like amino acids and colored dissolved and particulate matter to sea ice optical properties and ultraviolet attenuation
Authors: Uusikivi Jari , Vähätalo Anssi V. , Granskog Mats A. , Sommaruga Ruben
Published: August 2016

In the Baltic Sea ice, the spectral absorption coefficients for particulate matter (PM) were about two times higher at ultraviolet wavelengths than at photosynthetically available radiation (PAR) wavelengths. PM absorption spectra included significant absorption by mycosporine‐like amino acids (MAAs) between 320 and 345 nm. In the surface ice layer, the concentration of MAAs (1.37 µg L−1) was similar to that of chlorophyll a, resulting in a MAAs‐to‐chlorophyll a ratio as high as 0.65. Ultraviolet radiation (UVR) intensity and the ratio of UVR to PAR had a strong relationship with MAAs concentration (R2 = 0.97, n = 3) in the ice. In the surface ice layer, PM and especially MAAs dominated the absorption (absorption coefficient at 325 nm: 0.73 m−1). In the columnar ice layers, colored dissolved organic matter was the most significant absorber in the UVR (< 380 nm) (absorption coefficient at 325 nm: 1.5 m−1). Our measurements and modeling of UVR and PAR in Baltic Sea ice show that organic matter, both particulate and dissolved, influences the optical properties of sea ice and strongly modifies the UVR exposure of biological communities in and under snow‐free sea ice.
Mixing and its effects on biogeochemistry in the persistently stratified, deep, tropical Lake Matano, Indonesia
Authors: Katsev Sergei , Crowe Sean A. , Mucci Alfonso , Sundby Bjørn , Nomosatryo Sulung , Douglas Haffner G. , Fowle David A.
Published: August 2016

In the > 590‐m deep, tropical Lake Matano (Indonesia), stratification is characterized by weak thermal gradients (< 2°C per 500 m) and weak salinity gradients (< 0.14% per 500 m). These gradients persist over seasons, decades, and possibly centuries. Under these nearly steady‐state conditions, vertical eddy diffusion coefficients (Kz) cannot be estimated by conventional methods that rely on time derivatives of temperature distributions. We use and compare several alternative methods: one‐dimensional k‐ε modeling, three‐dimensional hydrodynamic modeling, correlation with the size of Thorpe instabilities, and correlation with the stability frequency. In the thermocline region, at 100‐m depth, the Kz is ~ 5 × 10−6 m2 s−1, but, below 300 m, the small density gradient results in large (20 m) vertical eddies and high mixing rates (Kz ~ 10−2 m2 s−1). The estimated timescale of water renewal in the monimolimnion is several hundred years. Intense evaporation depletes the surface mixed layer of 16O and 1H isotopes, making it isotopically heavier. The lake waters become progressively isotopically lighter with depth, and the isotopic composition in the deep waters is close to those of the ground and tributary waters. The vertical distribution of Kz is used in a biogeochemical reaction‐transport model. We show that, outside of a narrow thermocline region, the vertical distributions of dissolved oxygen, iron, methane, and phosphorus are shaped by vertical variations in transport rates, rather than by sources or sinks.
Synergistic nutrient colimitation across a gradient of ecosystem fragmentation in subtropical mangrove‐dominated wetlands
Authors: Allgeier Jacob E. , Rosemond Amy D. , Mehring Andrew S. , Layman Craig A.
Published: August 2016

We examined benthic algal response to nutrient enrichment by nitrogen (N), phosphorus (P), and N + P in mangrove wetlands of The Bahamas, to test the hypothesis that human impacts (fragmentation) on these ecosystems altered nutrient limitation, thereby changing the frequency and/or magnitude at which ecological synergies occurred. Fragmentation occurred due to road construction, resulting in reduced hydrological connectivity between the wetlands and marine environment. Strong, persistent, and synergistic nutrient colimitation occurred in both pristine and fragmented estuaries. Ecosystem fragmentation did not alter the biomass response to dual nutrient enrichment, but did alter the relative magnitude of the nonadditive response. That is, synergistic responses were less extreme in fragmented systems. This was supported by the strong, negative relationship between ambient algal biomass (a surrogate for background productivity) and the strength of synergistic responses (R2 = 0.69 and 0.79, year 1 and year 2, respectively). Bahamian coastal ecosystems exhibited the greatest synergistic responses reported for a marine ecosystem, suggesting that the benthic algal communities associated with Bahamian wetlands are among the most nutrient‐limited marine ecosystems. Our findings provide a case study illustrating how altered nutrient dynamics associated with land‐use change may decrease the frequency and/or magnitude of synergistic responses to nutrients in aquatic ecosystems.
Effects of nutrients and physical lake characteristics on bacterial and phytoplankton production: A meta‐analysis
Authors: Faithfull C. L. , Bergström A.-K. , Vrede T.
Published: August 2016

We performed a meta‐analysis comprising field (300 studies) and experimental data (249 studies) from a wide range of lake trophic states and locations. We examined the effects of nitrogen (N), phosphorus (P), carbon (dissolved organic matter [DOM]), temperature, latitude, and lake morphometry on the absolute and relative rates of phytoplankton primary production (PPr) and secondary bacterial production (BP). Areal and volumetric rates of PPr, BP, and BP : PPr were compared, and we analyzed differences between experimental and natural systems. Both field studies and experimental results showed agreement with regard to N and P as predictors of volumetric PPr and BP, respectively, despite the large variation in study duration, size, and nutrient addition rates in experimental systems. This indicates that bacteria and phytoplankton do not seem to be competing for the same nutrients. Areal measurements were more difficult to predict and were more dependent on physical lake characteristics than nutrients. Temperature was positively correlated with PPr, but not with BP. BP : PPr was stable across experiments regardless of N, P, DOM, or glucose additions. In contrast, BP : PPr ratios varied greatly in the field data set and were highest in systems with low total N and at high latitudes. This pattern was driven by reduced PPr, not BP; therefore, experimenters may need to manipulate PPr to change BP : PPr. Collectively, our results indicate that increased temperatures and N availability will lead to higher PPr and lower BP : PPr, potentially decreasing the importance of energy mobilized through the microbial food web on a global scale.
Grazer‐induced chain length plasticity reduces grazing risk in a marine diatom
Authors: Bergkvist Johanna , Thor Peter , Jakobsen Hans Henrik , Wängberg Sten-Åke , Selander Erik
Published: August 2016

We show that Skeletonema marinoi suppresses chain formation in response to copepod cues. The presence of three different copepod species (Acartia tonsa, Centropages hamatus, or Temora longicornis) significantly reduced chain length. Furthermore, chain length was significantly reduced when S. marinoi was exposed to chemical cues from caged A. tonsa without physical contact with the responding cells. The reductions in chain length significantly reduced copepod grazing; grazing rates on chains (four cells or more) were several times higher compared to that of single cells. This suggests that chain length plasticity is a means for S. marinoi to reduce copepod grazing. In contrast, chain length was not suppressed in cultures exposed to the microzooplankton grazer Gyrodinium dominans. Size‐selective predation may have played a key role in the evolution of chain formation and chain length plasticity in diatoms.
Mixing of an interflow into the ambient water of Lake Iseo
Authors: Hogg Charlie A. R. , Marti Clelia L. , Huppert Herbert E. , Imberger Jörg
Published: August 2016

River water flowing as an interflow was investigated using field data, collected in Lake Iseo (Italy), and theory. A theory for the lateral falling mechanism of plunging was developed for inflows when the initial densimetric Froude number (Fr0) is slightly larger than unity. The ratio of the river width to the offshore extent of the plunge region was equal to Fr0. The mixing ratio in the plunge region was 0.06. Theoretical results were quantitatively consistent with the length scale and mixing ratio of the observed plunge region. The progression of the inflow was interpreted as: initially a laterally falling plunge region with little mixing; followed by a steep underflow region with substantial mixing; and finally an intrusion. The intrusion was at first controlled dynamically by an inertia‐buoyancy force balance. Further from the liftoff point, turbulent mixing effects dominated over those due to inertia. Ultimately, the intrusion diffused into the adjacent layers in such a way that the interflow fluid was effectively indistinguishable from the lake water.