bluuebunny/crossref_metadata_2025 huggingface dataset:
Steady State Analysis and Optimization for Autonomous Underwater Vehicle
Authors: Liu Peng , Liu YongHong , Cai BaoPing , Niu ZhenWei , Wei XiaoXuan
Published: October 2019

Autonomous Underwater Vehicle (AUV) is widely used in ocean engineering field. Steady state analysis of AUV is considered as a necessary part in the design process. Motivated by improving the stability, a downwash filter based feedback optimization methodology for AUV is presented. First, combined with AUV structural parameters, the AUV four-degree of freedom motion space mathematical model is calculated to provide a mathematical basis for rock-bottom steady state control system. Second, the transfer function of the filter is derived according to the zero-pole and trajectory map of the AUV ontic system. Finally, the AUV optimized control system is established by series downwash filter. The simulation analysis result shows that the stability of the system is greatly increased after the whole system is connected to the filter.
Analysis of the mechanical response of materials used in design for highly stressed components
Authors: Brnic Josip , Krscanski Sanjin , Brcic Marino
Published: October 2019

In this paper both the mechanical properties and responses of materials usually used in engineering for design and manufacture of highly stressed components were considered. Between the materials used for the aforementioned purposes are considered the following steel alloys: 30CrNiMo8, 20MnCr5, 51CrV4. Investigated mechanical properties of the materials were ultimate tensile strength, yield strength and modulus of elasticity, while in the area of mechanical responses were explored / tested creep behaviour and fatigue of the considered materials. In general, all of the responses are presented in the form of stress-strain curves, creep curves and S-N curves (maximum applied stress versus the number of the cycles to failure). Mechanical properties were tested at different temperatures, creep behaviour was investigated at different temperatures when material was subjected to stresses at prescribed percentage of yield strength while fatigue of the considered materials was investigated on smooth unnoched specimen for prescribed maximum uniaxial stress and for prescribed stress ratio. In addition, all of obtained data were analysed and compared regarding the type of used materials.
Feasibility of producing unfired four-hole hollow bricks from blended cement-fly ash-chippings under coupled-static forming pressure
Authors: Huynh Trong-Phuoc , Do Ngoc-Duy , Hwang Chao-Lung , Ngo Si-Huy , Mai Ngoc-Hang Thi
Published: October 2019

Unfired four-hole hollow brick (UFHB) is a type of environmental-friendly brick with low energy consumption. However, the using of ordinary Portland cement (OPC) in UFHB is costly and indirectly affects the environment. This paper focuses on an exploratory study on the use of blended fly ash (FA)-OPC in the production of the UFHB and proposes the application of FA-OPC mixtures as a timely solution for the reduction of OPC in UFHB. The 80×80×180 mm UFHB samples were produced using different proportions of FA and OPC under a constant coupled-static forming pressure. The report exhibited experimental characterizations on physical and mechanical properties of both starting materials and UFHB products. In addition, a scanning electron microscope (SEM) analysis was used to evaluate the microstructure of the final UFHB. Test results show that the inclusion of FA in the UFHB mixtures provided positive effects on brick properties. As a result, 10% FA was found as an optimal content, which resulted in the highest brick’s strength, the lowest water absorption rate, and a denser microstructure. Furthermore, properties of all of the UFHB samples produced for this study satisfied the requirements of the National Vietnamese standard for non-bearing building brick.
Synthesis of carbon nanoparticles using various electrolyte concentrations in submerged glow discharge plasma
Authors: Ranjit M S , Julaihi M R M
Published: October 2019

This research aims to study the effects of the manipulation of the concentration of electrolyte on the synthesis and size control of carbon nanoparticles. Submerged glow-discharge plasma (SGDP) method was used which is a type of electrolysis. This method was proven to be both cost effective and eco-friendly in the synthesis of nanoparticles. Carbon nanoparticles generally range from 1 to 100nm and its small size gives it a high surface area to low volume ratio which gives it an edge over the sheet and bulk metals. They vary in their mechanical properties with respect to their sizes which makes it ideal for the manufacturing industry. The ability to control carbon nanoparticle size will give manufacturers the ability to obtain the desired mechanical properties. This research brings the potential of being able to control the size of carbon nanoparticles with a simple and cost-effective method by changing the concentration of electrolyte and plasma discharge voltage. The manufacturing industry in the future can benefit from this research as they will be able to manufacture materials with better mechanical properties at a cheaper cost.
U(1) gauge symmetry free of redundancy and a generalized Byers-Yang theorem
Authors: Kang Kicheon
Published: October 2019

We present a reformulation of the U(1) gauge theory by eliminating the redundancy inherent in the conventional approach. Our reformulation is constructed on the basis of local field interaction approach to electrodynamics. The gauge symmetry in our framework is associated with a physical transformation, which represents the invariance of the equation of motion of a charged scalar field under the change in the distribution of electromagnetic field at a distance. We demonstrate that all physical properties of the U(1) gauge theory are preserved with the removal of redundancy in the gauge field. In addition, our reformulation provides a generalization of the Byers-Yang theorem to open systems.
Coupled trophic and contaminant analysis in seabirds through space and time
Authors: Gagné Tyler O , Johnson Elizabeth M , Hyrenbach K David , Hagemann Molly E , Bass Oron L , MacDonald Mark , Peck Brian , Van Houtan Kyle S
Published: October 2019

Wildlife contaminant loads are often used to indicate ecosystem health, but their interpretation is complicated by the dynamics affecting the trophic transfer of toxins. Yet, coupled analyses of trophic position and contaminants may provide insights that help resolve the underlying signal of contaminants in ecosystems. Here, we analyze heavy metal concentrations and trophic positions for pelagic seabirds across time and space. We derive metal-specific trophic transfer coefficients from the literature and use them to interpret the changes in raw heavy metal concentrations in two settings: (i) for eight seabird species across a 125-year timeline in Hawaii, and (ii) for contemporary specimens of two tern species across three ocean basins. While previous studies report how trophic position varies in these two settings, here we investigate how trophic downgrading may affect the observed raw changes in contaminants. Using this approach, we find the highly-toxic metal elements (Hg, As, Pb) decline after 1980. However, several other metals (Cu, Mn, Mo, Cd, Fe) increase from 1990–2015. Though simultaneous biomagnification and trophic downgrading may obscure contaminant analyses across space and time, the trophic declines we observed (≤0.5 trophic level) are likely not sufficient to influence such comparisons. In addition, as extrapolating contaminant concentrations across broad ranges of trophic levels may be prone to large uncertainties, careful selection of the focal species for analysis is required. While high trophic level species, such as long-lived, fish-eating seabirds, are ideal for monitoring environmental contaminants across large spatial or time scales, lower trophic level species, like primary producers and consumers, may be more suitable for quantifying the concentrations of bio-available contaminants entering the marine ecosystem and the base of the marine food webs. Monitoring low and high trophic levels simultaneously may provide an integrated perspective that is needed to quantify the contaminants entering and bio-magnifying through marine ecosystems.
Multi-octave spanning, Watt-level ultrafast mid-infrared source
Authors: Butler T P , Lilienfein N , Xu J , Nagl N , Hofer C , Gerz D , Mak K F , Gaida C , Heuermann T , Gebhardt M , Limpert J , Krausz F , Pupeza I
Published: October 2019

We present a source of brilliant mid-infrared radiation, seamlessly covering the wavelength range between 1.33 and 18 μm (7500–555 cm−1) with three channels, employing broadband nonlinear conversion processes driven by the output of a thulium-fiber laser system. The high-average-power femtosecond frontend delivers a 50 MHz train of 250 fs pulses spectrally centered at 1.96 μm. The three parallel channels employ soliton self-compression in a fused-silica fiber, supercontinuum generation in a ZBLAN fiber, and difference-frequency generation in GaSe driven by soliton self-compressed pulses. The total output enables spectral coverage from 1.33 to 2.4 μm, from 2.4 to 5.2 μm, and from 5.2 to 18 μm with 4.5 W, 0.22 W and 0.5 W, respectively. This spatially coherent source with a footprint of less than 4 m2 exceeds the brilliance of 3rd-generation synchrotrons by more than three orders of magnitude over 90% of the bandwidth.
Skills and Journalism
Authors: Örnebring Henrik
Published: October 2019

What skills do journalists need? Why do they need them? What do we even mean by “skill” in the first place? In journalism research, the issue of skill has mainly been studied as an applied issue closely linked to journalism education. The main concern has been whether journalism education equips students with the skills they need to succeed in the job market, as well as with the skills they need to fulfill journalism’s democratic function. There is a long-standing conflict between these two “skill goals” of journalism education, where vocational or practical skills are often viewed as (at least potentially) in opposition to academic or theoretical skills. Journalism students need vocational skills in order to satisfy employer needs, and academic skills in order to satisfy wider societal needs.

Another key research concern in this area has been the issue of de-skilling: the idea that journalistic work gradually becomes less and less skilled as employers mainly demand quicker outputs across different media platforms, rather than the production of quality content. Another element of the deskilling idea is that experienced (older) journalists are phased out and/or replaced with less experienced (younger) and therefore cheaper journalists who do not necessarily possess specific or very in-depth training in journalism. This process is mainly linked to the ongoing commercialization and digitalization of journalism. Empirically, however, many research results point instead either to a general upskilling of journalism (a higher and higher share of the workforce have a university degree, for example) or to the fact that deskilling may occur in parts of the occupation, whereas other parts may experience upskilling.

All of this research has in common that skill is rarely defined and that analyses of skill rarely reference the wider sociological and psychological literature on skill, expertise, and competence. A few scholars have analyzed skill among journalists at a higher level of abstraction, attempting to define what the core expertise or skill of journalism actually is. This research direction is key to the future development of research on journalism and skill.
Electoral Choice and Religion: Turkey
Authors: Çarkoğlu Ali
Published: October 2019

With a conservative party in power since 2002 that has its roots in the pro-Islamist movement, the influence of religiosity upon party choice has attracted a lot of attention in the literature on Turkish elections and voting behavior. However, this literature uses measures of religiosity that change from one study to another and hence diagnosing trends over time or assessments concerning the influence of religiosity remains challenging. This article aims to first review the findings concerning the effect of religiosity upon party choice in Turkey. Second, using the Turkish Election Studies data for four general elections in the 2002–2015 period a unified comparable framework is adopted to evaluate the changing nature of the influence of religiosity upon party choice. The findings reached suggest that religiosity remains a potent variable in shaping party choice. However, over time and across parties its influence varies. A sectarian divide between the Sunni majority and the Alevi minority also appears to be useful especially differentiating the left-leaning main opposition party. This sectarian divide also seems to be shifting over time.
Southern Theory and Postcolonial Comparative Education
Authors: Mukherjee Mousumi
Published: October 2019

Since the late 1960s and early 1970s, there has been a great deal of criticism of the colonial heritage of early ethnographic research. In the first decade of the twenty-first century, scholars have also raised concerns also about the colonial heritage of comparative education. Erwin Epstein defined comparative education as “the application of the intellectual tools of history and social sciences to understand international issues of education.” Hence it is important for comparative education as a global field of study to engage with the recent debates in social sciences to generate deeper understanding about educational problems embedded within specific international contexts. The dominance of Northern theory in analyzing research data from the Global South has been increasingly critiqued by scholars in a number of scholarly publications since Raewyn Connell published her book Southern Theory in 2008. They have argued that Northern theory arising out of the colonial metropole is provincial in nature and, therefore, provides incomplete interpretation of data and generates misunderstanding or limited understanding of social phenomenon occurring in the hybrid contexts of the Global South. Therefore, lately scholars have been debating about postcolonial comparative education to argue for the relevance of Southern theory in conducting postcolonial comparative education research for both analytic (ideological), as well as hermeneutic (affective historical) engagement with research data. Drawing on the methodological insights from an empirical case study, this article demonstrates why Southern theory drawing on Tagore’s philosophy of education was found more suitable to analyze research data arising out of a case study designed to conduct an institutional ethnography in a particular international context. It demonstrates how contextually relevant Southern theory helped to provide deeper comparative understanding (verstehen) of a social phenomenon, i.e. inclusive pedagogic work of an old colonial school within a particular historical, geopolitical and cultural context in postcolonial India.
Attention to age: similar dosing regimens lead to different vancomycin levels among older and younger patients
Authors: Yahav Dafna , Abbas Maria , Nassar Laila , Ghrayeb Alia , Shepshelovich Daniel , Kurnik Daniel , Leibovici Leonard , Paul Mical
Published: October 2019

Background

little is known on the clinical implications of vancomycin trough levels among older patients.

Objective

to evaluate the association between vancomycin levels and outcomes among older versus younger patients.

Design

retrospective study.

Subjects

patients aged 18–64 and ≥65 years treated with vancomycin for documented methicillin resistant Staphylococcus aureus (MRSA) infections.

Methods

we compared the effectiveness and toxicity of vancomycin according to trough levels in older versus younger patients. Subgroup analysis of patients with glomerular filtration rate (GFR) > 60 ml/min/1.73 m2 was performed.

Results

we included 181 patients aged ≥65 years and 104 younger patients. Mean age in the older group was 76.9 ± 8 years versus 50.9 ± 12.4 in the younger group. Vancomycin trough levels and 24-hours area under the curve to minimal inhibitory concentrations (AUC/MIC) were significantly higher in older patients who were also significantly more likely to achieve trough levels of ≥15 mg/l within 4 days, (98/181 (54.1%) vs. 38/104 (36.5%) in younger patients, P = 0.004). Results were similar among patients with GFR > 60. Thirty-day mortality was significantly higher in older (74/181, 40.9% vs. 13/104, 12.5%, respectively, P < 0.001). There was no association between vancomycin trough levels and mortality among older patients. No significant differences were demonstrated in clinical or microbiological success or nephrotoxicity.

Conclusions

applying uniform dosing recommendations across age groups among adults with MRSA infections results in higher vancomycin levels and AUC/MIC in older versus younger patients. Yet, mortality rates remain higher among older adults. Prospective studies are needed to define the optimal approach for using this drug in older patients.
When Time is of the Essence: Preliminary Findings for a Quick Administration of the Dot Counting Test
Authors: Bailey K Chase , Webber Troy A , Phillips Jacob I , Kraemer Lindsay D R , Marceaux Janice C , Soble Jason R
Published: October 2019

Objective

Performance validity research has emphasized the need for briefer measures and, more recently, abbreviated versions of established free-standing tests to minimize neuropsychological evaluation costs/time burden. This study examined the accuracy of multiple abbreviated versions of the Dot Counting Test (“quick” DCT) for detecting invalid performance in isolation and in combination with the Test of Memory Malingering Trial 1 (TOMMT1).

Method

Data from a mixed clinical sample of 107 veterans (80 valid/27 invalid per independent validity measures and structured criteria) were included in this cross-sectional study; 47% of valid participants were cognitively impaired. Sensitivities/specificities of various 6- and 4-card DCT combinations were calculated and compared to the full, 12-card DCT. Combined models with the most accurate 6- and 4-card combinations and TOMMT1 were then examined.

Results

Receiver operator characteristic curve analyses were significant for all 6- and 4-card DCT combinations with areas under the curve of .868–.897. The best 6-card combination (cards, 1-3-5-8-11-12) had 56% sensitivity/90% specificity (E-score cut-off, ≥14.5), and the best 4-card combination (cards, 3-4-8-11) had 63% sensitivity/94% specificity (cut-off, ≥16.75). The full DCT had 70% sensitivity/90% specificity (cut-off, ≥16.00). Logistic regression revealed 95% classification accuracy when 6-card or 4-card “quick” combinations were combined with TOMMT1, with the DCT combinations and TOMMT1 both emerging as significant predictors.

Conclusions

Abbreviated DCT versions utilizing 6- and 4-card combinations yielded comparable sensitivity/specificity as the full DCT. When these “quick” DCT combinations were further combined with an abbreviated memory-based performance validity test (i.e., TOMMT1), overall classification accuracy for identifying invalid performance was 95%.
Nest Attendance of Parent Birds in the Painted Snipe (Rostratula benghalensis)
Authors: Komeda Shigemoto
Published: October 2019

I observed 15 pairs of Painted Snipes (Rostratula benghalensis) in Japan for 24-h periods in order to compare the nest attendance behavior of males and females and to document changes in their behavior during the laying period. From a few days before the laying of the first egg until the day the second egg was laid, the male and female consorted with each other (stayed within 5 m of each other) more than 90% of the observation time. They visited the nest repeatedly on the first and second days of laying. On the third day, the consorting ratio decreased to 58.5%, and the male typically started to incubate. He continued to incubate that night. After laying the third egg, the female usually did not visit the nest except to lay the fourth and last egg. The male continued incubation, and the female met her mate only when she laid the last egg. The absence of female incubation and the early termination of consorting behavior are consistent with the possibility that Painted Snipe females are polyandrous.
Fruits and the Ecology of Resplendent Quetzals
Authors: Wheelwright Nathaniel T.
Published: October 2019

Resplendent Quetzals (Pharomachrus mocinno) are typically termed "specialized" fruit-eating birds, although there are few data describing the breadth of their diet or the characteristics of the fruits they select. In fact, there is no general consensus about the meaning or consequences of being a fruit specialist. In the lower montane forests at Monteverde, Costa Rica, quetzals feed on a minimum of 12-18 species of fruits at most times of the year and on an annual total of at least 41 species. Although their diet includes the watery, small-seeded berries of many second-growth plants, they depend mostly on the large drupes of about 18 species in the laurel family (Lauraceae). The phenologies and habitat distributions of the Lauraceae appear to dictate the timing and direction of seasonal movements by quetzals. Mutual dependence and, possibly, general coevolution between quetzals and the lauraceous trees whose seeds they disperse are suggested by the birds' morphology, distribution, behavior, and life history.

Nestling quetzals are brought entire fruits as early as the second day after hatching. Thereafter, they consume gradually increasing amounts of fruit, but, even immediately before they fledge, most of their diet consists of insects, snails, and lizards. Brooding drops off rapidly by the time chicks are 9 days old. Considerable variation in brooding duration, parental sex roles, and nestling diet exists between nests, however, and apparently between clutches. Adults take far less time to deliver fruits to nestlings than to deliver insects or lizards, which reflects the relative ease of "capturing" ripe fruits (as opposed to animal prey) during the breeding season. The male parent delivered significantly more insects and food items in general than did the female at a first-clutch nest but not at a second-clutch nest.

Several Central American montane reserves have been established to protect populations of quetzals, the national symbol of Guatemala and an important tourist attraction throughout the Isthmus. Unfortunately, the reserves tend to be too small and to include only a limited representation of critical habitats. If other Central American quetzal populations are similar to Monteverde's, the birds must migrate to different habitats as the availability of ripe fruits fluctuates between seasons or years. Once reserves become isolated by deforestation, they will fail to prevent local extinction of quetzals.
Mechanism and Ecological Significance of Sperm Storage in the Northern Fulmar with Reference to Its Occurrence in Other Birds
Authors: Hatch Scott A.
Published: October 2019

Sperm-storage glands were found in the uterovaginal (UV) region of the oviduct in Northern Fulmars (Fulmarus glacialis), Horned Puffins (Fratercula corniculata), and Leach's Storm-Petrels (Oceanodroma leucorhoa) collected before or shortly after egg laying. Previously described only in domestic Galliformes, UV sperm-storage glands may prove to be a common feature of the avian reproductive system. There is as yet no compelling explanation of their function in the Horned Puffin. In the Northern Fulmar, and probably in other petrels, however, sperm-storage glands allow the separation of the male and female over pelagic waters for several weeks immediately before egg laying. The likelihood of prolonged viability of sperm in the female reproducitve tract should be considered in interpreting the sexual behavior of other wild birds.
The Relationships of the Starlings (Sturnidae: Sturnini) and the Mockingbirds (Sturnidae: Mimini)
Authors: Sibley Charles G. , Ahlquist Jon E.
Published: October 2019

Old World starlings have been thought to be related to crows and their allies, to weaverbirds, or to New World troupials. New World mockingbirds and thrashers have usually been placed near the thrushes and/or wrens. DNA-DNA hybridization data indicated that starlings and mockingbirds are more closely related to each other than either is to any other living taxon. Some avian systematists doubted this conclusion. Therefore, a more extensive DNA hybridization study was conducted, and a successful search was made for other evidence of the relationship between starlings and mockingbirds. The results support our original conclusion that the two groups diverged from a common ancestor in the late Oligocene or early Miocene, about 23-28 million years ago, and that their relationship may be expressed in our passerine classification, based on DNA comparisons, by placing them as sister tribes in the Family Sturnidae, Superfamily Turdoidea, Parvorder Muscicapae, Suborder Passeres. Their next nearest relatives are the members of the Turdidae, including the typical thrushes, erithacine chats, and muscicapine flycatchers.
Energy Invested in Reproduction by Thick-Billed Murres (Uria lomvia)
Authors: Gaston A. J.
Published: October 2019

Pelagic seabirds that lay single-egg clutches have been thought to invest less energy in reproduction than inshore-feeding species that rear more than one young. To examine this idea I calculated time and energy budgets for Thick-billed Murres (Uria lomvia) breeding at two large arctic colonies and compared their energy expenditure with that of a hypothetical group (shirkers) that was capable of feeding at the same rate but did not attempt any reproductive activity. The difference in energy investment between breeders and shirkers was strongly dependent on the average foraging range. I also compared my results with similar estimates for inshore-feeding Black Guillemots (Cepphus grylle). For the two Thick-billed Murre colonies, energy allocated to reproduction represented 30% and 24% of total energy expenditure during the breeding season. These values exceed the estimates for Black Guillemots. The amount of energy invested by Thick-billed Murres at the colonies considered probably is similar to that invested by other seabirds laying larger clutches and rearing heavier young.
Courtship Feeding and Osprey Reproduction
Authors: Poole Alan
Published: October 2019

A female Osprey (Pandion haliaetus) usually is fed exclusively by its mate between pair formation and egg-laying. Laying dates and courtship periods-but not clutch size, egg size, breeding success, or female weight reserves-were correlated (negatively) with the prelaying feeding rates of 12 females breeding in a coastal Massachusetts colony. However, the age of a pair and of its bond influenced laying dates and courtship periods more than food intake. Older and more experienced pairs arrived earlier and laid eggs more quickly than younger pairs. As an independent test of food limitation in Ospreys producing eggs, supplemental food was provided to 4 nests during courtship. Supplemental food did not influence a female's reproductive output or timing, but males at nests receiving extra food showed reduced rates of foraging. Egg production boosted the daily energy expenditure of female Ospreys by only about 20% and females gained little weight during courtship, suggesting that egg-laying is not a demanding process in this species. Because age and mate retention had a greater effect on the reproductive output and timing of female Ospreys than rates of food consumption during courtship, and because there was evidence that poorly fed females were less willing to copulate and less faithful to their mates than well-fed females, it is argued that Osprey courtship feeding may function primarily to ensure mate fidelity.
Coloniality in the Yellow-Rumped Cacique as a Defense against Nest Predators
Authors: Robinson Scott K.
Published: October 2019

Individuals of the colonial Yellow-rumped Cacique (Cacicus cela) in Amazonian Peru can defend their nests against predators in three ways. First, by nesting on islands and around wasp nests, caciques are safe from arboreal mammals such as primates, which destroy many more-accessible colonies. Caimans and otters that live in lakes also protect island colonies from snakes, which are vulnerable when crossing open water. Second, by clustering nests together and mobbing as a group, caciques can deter many avian predators, which take spatially isolated nests in small colonies. The effectiveness of mobbing increases with group size, which in turn is correlated with colony size. Third, by mixing their enclosed, pouchlike nests with abandoned nests, caciques can hide their nests from some predators. Overall, nests in clusters on islands and around wasp nests suffer the least predation, largely because they are well protected against the cacique's major predators. Females switch colonies after losing nests to a predator, usually to sites that offer protection against that predator. By this mechanism, the best colony sites accumulate the largest numbers of nests. It is unclear, however, why all females do not nest in the safest colony sites. I argue that nest predation favors coloniality because of the scarcity of nest sites that are safe from mammals and the increased effectiveness of group defense.
Moonlight Avoidance Behavior in Leach's Storm-Petrels as a Defense against Slaty-Backed Gulls
Authors: Watanuki Yutaka
Published: October 2019

Diurnal activity patterns of Leach's Storm-Petrels (Oceanodroma leucorhoa) and Slaty-backed Gulls (Larus schistisagus) were investigated. The petrels reduced activity in moonlight in May and June when the predation rate by gulls was relatively high. Petrel activity levels were inversely correlated with light intensities and the corresponding risk of predation by the gull. This suggests that nocturnal activity and moonlight avoidance by the petrel in its colony are an effective defense against diurnal predators. Activity synchronization of the petrel was most marked during the full moon, further supporting the predator-avoidance hypothesis.
Effects of Body Weight and Age on the Time of Pairing of American Black Ducks
Authors: Hepp Gary R.
Published: October 2019

I used captive young and adult American Black Ducks (Anas rubripes) during October-February 1984-1985 to test whether body weight and age affected time of pair-bond formation. Eighty ducks were marked individually, and 10 ducks (6 males and 4 females, half of each age class) were assigned to each of 8 experimental pens. Ducks in 4 pens received an ad libitum diet of commercial duck food, and ducks in the other 4 pens received a restricted ration of the same food. During early winter ducks in both groups gained weight, but ducks on the restricted diet gained less than birds on the ad libitum diet; peak winter weight of ducks on the ad libitum diet averaged 22% greater than initial body weight compared with 6.5% for ducks on the restricted diet. In late winter ducks on the restricted diet lost 28.7% of peak winter weight, and ducks on the ad libitum diet lost 19.3%. Weight loss of ducks on the ad libitum diet began before weather conditions became severe and coincided with a reduction in food consumption. This result supports the idea that weight loss of waterfowl in late winter is controlled endogenously. Individuals on the ad libitum diet paired earlier than those on the restricted diet, and pair bonds were stronger. Adults of both sexes paired earlier than young ducks, but differences for females were not significant statistically. Age and energy constraints are factors that can affect intraspecific variation in pairing chronology.
Predation as a Selective Force on Foraging Herons: Effects of Plumage Color and Flocking
Authors: Caldwell Gloria S.
Published: October 2019

Experiments using model herons in natural mangrove habitats demonstrated that more hawks are attracted to white than to blue herons. Both Common Black-Hawks (Buteogallus anthracinus) and crocodiles (Crocodylus acutus) were observed preying on adult herons in Panama. Solitary herons were at greater risk than flocked foragers. White (immature) Little Blue Herons (Egretta caerulea) were attacked more frequently by hawks than were the blue adults of their species. Dark herons gave more alarms than white herons. Although flock size decreased in years of heavy predation and after attacks, mixed-flock composition remained the same. When flocks re-formed after hawk attacks, their members showed decreased foraging rates and increased interindividual distances. After repeated attacks, herons foraged in poorer habitats, under unfavorable climatic conditions, and under thermoregulatory stress. These results suggest that predation could be a potent force in maintaining color dimorphism in ardeids.
Fish Crow Predation on Eggs of the White Ibis at Battery Island, North Carolina
Authors: Shields Mark A. , Parnell James F.
Published: October 2019

We studied predation by Fish Crows (Corvus ossifragus) on eggs of the White Ibis (Eudocimus albus) during the 1983 and 1984 nesting seasons at Battery Island, southeastern North Carolina. Crow predation accounted for the loss of 32% (n = 223) of ibis eggs in 1983 and 44% (n = 538) in 1984. Crows usually took all eggs in a clutch. An estimated 6 pairs of Fish Crows nested on the island each year. We believe these individuals were responsible for most egg loss. The predation rate of ibis clutches was highest in plots nearest crow nests and lowest in two plots that contained observation blinds. Results of experiments using simulated ibis nests suggested that crows were wary of the blinds. Predation declined with nest age, apparently due to increased nest attentiveness by adult ibises during the last week of incubation. The overall predation rate in 1984 was significantly higher than in 1983. Greater nest densities and less synchronous breeding by ibises in 1984 may have contributed to the higher predation rate. Ibis productivity was estimated at 1.22-1.30 fledglings per pair in 1983 and 1.05-1.12 in 1984. This level of reproduction appeared sufficient for maintenance of the population. Thus, egg predation by Fish Crows during our study did not appear to be a serious threat to the productivity of this White Ibis population.
Behavioral and Ecological Correlates of Interference Competition among Some Hawaiian Drepanidinae
Authors: Carothers John H.
Published: October 2019

Interference interactions were studied on the island of Maui among four species of drepanidines that fed on canopy flowers of the ohia tree (Metrosideros collina). The birds had a size-related dominance hierarchy, with ranking (most to least dominant, by location in dominance matrix) as follows: Crested Honeycreeper (Palmeria dolei), Iiwi (Vestiaria coccinea), Apapane (Himatione sanguinea), and Common Amakihi (Hemignathus virens). Immatures were subordinate to conspecific adults. Crested Honeycreepers and Iiwis defended tree-canopy territories, Apapanes were nomadic flock foragers, and Common Amakihis were secretive foragers. Dominance by Iiwis was indicated by a lack of reversals in the dominance matrix. For the top-ranked Crested Honeycreeper dominance was also reflected in greater chase or greater resulting retreat distances or both. Age-related differences in interference behavior by dominants appeared to be due to inexperience, as indicated by shorter chase distances for immatures. Among subordinates both experience and plumage could be responsible for age differences in behavior. Immatures were chased equal distances (despite closer spacing) but less often than adults, and they chose safer retreat sites.

Apapanes fed in flocks in a dominant's tree. This increased a dominant's territorial costs, reduced chase frequencies, increased Apapane foraging times, and let Apapanes forage in trees from which they otherwise were excluded. Comparisons with the assemblage on the island of Hawaii suggested similar structure among the three species the two islands have in common. On Maui the bottom-ranked Common Amakihi may be more affected by interference competition, perhaps undergoing a niche shift toward greater insectivory because of an additional dominant.
Seabird Geographic Variation: Similarity Among Populations of Leach's Storm-Petrel
Authors: Power Dennis M. , Ainley David G.
Published: October 2019

We assessed geographic variation in 13 locality samples of Leach's Storm-Petrel (Oceanodroma leucorhoa), 12 from the Pacific coast and 1 from the Atlantic coast of North America. Nine phenetic characters were used with canonical variates analysis to determine similarity among samples. Regression of phenetic distance on geographic distance measured the relation between similarity and interisland distance. We found a clinal pattern of population similarity from the Aleutian Islands in the north to the Farallon Islands in the south. Populations from Los Coronados and San Benitos islands make up a distinct subset when rump color and wing and tail shape indices are included in the analysis, but these populations were part of a dominant clinal trend when only five size characters were used. On Guadalupe Island separate populations breed in summer and winter; these are strongly differentiated from the others and from each other. The North Atlantic sample was aligned closely with that from the Aleutians. The degree of geographic variation was roughly similar to that in certain migratory land birds on the North American continent, but is less than what is found for certain nonmigratory land birds on islands. Our results suggest recognizing four subspecies of Leach's Storm-Petrel in the study area, including two on Guadalupe Island isolated by time of breeding.
Sugar-Tasting Ability and Fruit Selection in Tropical Fruit-Eating Birds
Authors: Levey Douglas J.
Published: October 2019

The sugar-tasting abilities of four species of tanagers and two species of manakins were tested. Three tanager species were able to detect differences in diets containing 8%, 10%, and 12% sugar. In pairwise choice trials, they preferred the diet highest in sugar. Neither species of manakin discriminated among the three diets. This apparent difference in tasting abilities of tanagers and manakins may be a result of their fruit-handling techniques. Tanagers crush fruits in their bills, thereby releasing juices onto their tongues. Manakins swallow fruits whole; their tongues rarely encounter fruit juice. Hence, manakins' fruit-handling technique is poorly suited for sensing the taste cues in fruit juices. Variation in fruit sugar concentration is common within and among plant species and is great enough to be detected by birds. Birds probably have selected for sweeter fruits.
Energy Expenditure during Free Flight in Trained and Free-Living Eurasian Kestrels (Falco Tinnunculus)
Authors: Masman Dirkjan , Klaassen Marcel
Published: October 2019

During directional flight trained Eurasian Kestrels (Falco tinnunculus) in the laboratory expended 13.8 W. Free-living birds expended 14.6 W during nonsoaring flight that included both directional flight and wind hovering. The former value was obtained by combining food balance and indirect calorimetry techniques, the latter by doubly labeled water (Dz18O). Because the energy-expenditure rates are so similar for directional flight alone and for wind hovering and directional flight combined, we argue that the value for either mode of kestrel flight may be used to analyze time-energy budgets. We predicted avian flight costs (et) from an equation based on published data on flight costs in 14 species (body mass 3.8-1,000 g):

where M is body mass (g), bw is wing span (cm), and Sw is wing area (cm2). Inclusion of the morphological data with body mass significantly improved the prediction of flight cost [r2 = 0.84 vs. r2 = 0.75 without bw and sw, Fc (2,18) = 5.34, P < 0.05]. Received 8 May 1986, accepted 29 November 1986.
Cavity Roosting, Philopatry, and Cooperative Breeding in the Green Woodhoopoe May Reflect a Physiological Trait
Authors: Ligon J. David , Carey Cynthia , Ligon Sandra H.
Published: October 2019

Cooperative breeding in birds generally is related to a critical resource. A critical limiting factor for the Green Woodhoopoe (Phoeniculus purpureus) is the availability of roost cavities. Although predation at roost holes is the major source of mortality, woodhoopoes invariably roost in cavities or under loose bark. This dependence on cavities appears to be related to the birds' inability to cope physiologically with low nighttime temperatures. This is the first evidence to suggest that a physiological limitation has played a major role in the evolution of philopatry and possibly cooperative breeding in an avian species.
Experimental Evidence for Sibling Recognition in Common Terns (Sterna Hirundo)
Authors: Burger J. , Gochfeld M. , Boarman W. I.
Published: October 2019

Young Common Terns (Sterna hirundo) did not respond preferentially to calls of siblings at 8 and 9 days of age, but did so by 12 days of age. In experiments with and without visual isolation, and with use of playback, we demonstrated a tendency to approach sibling begging calls. This differential response indicated sibling-recognition occurred, was based on experience, and involved vocal cues.
A Mechanism of Sexual Segregation by Habitat in American Kestrels (Falco sparverius) Wintering in South-Central Florida
Authors: Smallwood John A.
Published: October 2019

I observed the establishment of 240 winter territories by American Kestrels (Falco sparverius) on a 293-km census route in south-central Florida during autumn 1985. Most females arrived before males. Analysis of banding records revealed that immatures of both sexes and adult females preceded adult males in autumn migration in eastern North America; thus, the sex ratio of early arrivals was skewed toward females. In south Florida territorial kestrels occupied habitats in decreasing order of foraging quality, as measured by percentage cover of suitable hunting substrate (grasses or weedy forbs < 25 cm in height) and woody canopy cover (which was correlated negatively with suitable hunting substrate and obstructed the view of hunting kestrels). Early-arriving males also occupied habitats of superior foraging quality and were as successful as females in defending territories against same-sex and opposite-sex kestrels as high-quality habitats became limited. Results of experiments in which free-flying intruder kestrels were released onto defended territories suggested that males defended winter territories more tenaciously than did females. Because there was no evidence of male submissiveness on the wintering grounds, the female-dominance hypothesis is not a plausible explanation for sexual segregation by habitat in wintering kestrels. Each kestrel's arrival date was apparently the principal determinant of the foraging quality of habitats still available for occupancy; foraging quality was correlated negatively with arrival date for the adult males and for the females and immatures. A delayed molt in adult males, associated with differential sex roles on the breeding grounds, may delay the migratory departure, resulting in the late arrival on the wintering grounds.
Nuclear DNA Evolution and Phylogeny of the New World Nine-Primaried Oscines
Authors: Bledsoe Anthony H.
Published: October 2019

Estimates of phylogeny were derived from measures of dissimilarity of single-copy nuclear-DNA sequences for 13 species that represent the currently recognized major groups of New World nine-primaried oscines and an outgroup (Passer). The dissimilarity coefficients (delta mode and delta T50H) calculated from thermal dissociation curves of reassociated DNA sequences exhibited the properties of a metric. No statistically significant increase in goodness-of-fit of the raw data to a phylogeny estimated from a least-squares analysis of the 13 × 13 matrix of distances was achieved when the lengths of sister branches were allowed to vary. "Jackknife" and negative branch-length analyses identified unstable stems that resulted from non-additivity caused in part by measurement error. Such stems were collapsed to produce a more robust topology, which served as the basis for estimating the positions of taxa not included in the 13 × 13 matrix.

The clade that subsumed several "typical" tanagers (e.g. Tachyphonus rufus) also included Sicalis luteola and Diuca diuca (usually allied with the North American emberizine sparrows); Cyanerpes cyaneus, two species of Diglossa, and Coereba flaveola (often split among several major groups); and Tersina viridis, Catamblyrhynchus diadema, and Nephelornis oneilli (whose affinities are often considered uncertain). This "tanager" clade and its sister group, the cardinals (represented by Cardinalis cardinalis), together formed one fork of a trichotomy. Several emberizine sparrows (e.g. Pooecetes gramineus) formed the second fork, and wood-warblers (e.g. Dendroica striata) and New World orioles (e.g. Psarocolius angustifrons) formed the third. The chaffinches (represented by Fringilla coelebs) and several cardueline finches (e.g. Carduelis pinus) together formed the sister group of the other New World nine-primaried oscines included in the study. This phylogeny implies that convergence in feeding specializations among lineages is more extensive than traditional arrangements of the assemblage would suggest.
Heightened perception of competition hastens courtship
Authors: Santori Claudia , Bussière Luc F , Houslay Thomas M
Published: October 2019

When animals use costly labile display or signal traits to display to the opposite sex, they face complex decisions regarding the degree and timing of their investment in separate instances of trait expression. Such decisions may be informed by not only the focal individual’s condition (or pool of available resources) but also aspects of the social environment, such as perceptions of same-sex competition or the quality of available mates. However, the relative importance of these factors to investment decisions remains unclear. Here, we use manipulations of condition (through dietary nutrition), recent social environment (exposure to a silenced male, nonsilenced male, female, or isolation), and female mating history (single or multiple male) to test how quickly male decorated crickets (Gryllodes sigillatus) decide to begin courting an available female. We find that males that were previously housed with nonsilenced males started courting the female earlier than other males. Females only mounted males after courtship began. Our results suggest a strong effect of the perception of competition on the decision to invest resources in sexual signaling behavior and that females might exert directional selection on its timing.
VISOR: a versatile haplotype-aware structural variant simulator for short- and long-read sequencing
Authors: Bolognini Davide , Sanders Ashley , Korbel Jan O , Magi Alberto , Benes Vladimir , Rausch Tobias
Published: October 2019

VISOR is a tool for haplotype-specific simulations of simple and complex structural variants (SVs). The method is applicable to haploid, diploid or higher ploidy simulations for bulk or single-cell sequencing data. SVs are implanted into FASTA haplotypes at single-basepair resolution, optionally with nearby single-nucleotide variants. Short or long reads are drawn at random from these haplotypes using standard error profiles. Double- or single-stranded data can be simulated and VISOR supports the generation of haplotype-tagged BAM files. The tool further includes methods to interactively visualize simulated variants in single-stranded data. The versatility of VISOR is unmet by comparable tools and it lays the foundation to simulate haplotype-resolved cancer heterogeneity data in bulk or at single-cell resolution.

Availability and implementation

VISOR is implemented in python 3.6, open-source and freely available at https://github.com/davidebolo1993/VISOR. Documentation is available at https://davidebolo1993.github.io/visordoc/.

Supplementary information

Supplementary data are available at Bioinformatics online.