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How Useful Are Existing Protocols in the Quick Assessment of the Welfare of Semi-Feral Horses? Pilot Study on Konik Polski Horses Living in the Forest Sanctuary. Animals (Basel) 2023; 14:8. [PMID: 38200740 PMCID: PMC10778358 DOI: 10.3390/ani14010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/02/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
Scientifically validated and standardised methods for the evaluation of the welfare of free-living horses are urgently needed by both the owners and managers of these populations and those responsible for implementing national welfare legislation. The aim of the study was to test the feasibility and usefulness of two welfare protocols that could be applied to semi-feral populations: a prototype of welfare assessment template (WAT) for Carneddau semi-feral ponies and the IFCE/INRAE Horse Welfare Protocol. Additionally, the body condition scale designed by Henneke (BCS-H) was employed. The study took place in July/August 2022 and April 2023 to evaluate the welfare of a pilot population of nineteen semi-feral Konik polski horses. The horses scored high or satisfactory under indicators across both protocols; only body condition scores were significantly lower in early spring (BCS-WAT: 1.11 ± 0.57; BCS-H: 3.84 ± 1.17) than in the summer (BCS-WAT: 1.58 ± 0.61; BCS-H: 5.63 ± 1.01). Our study confirmed the feasibility of utilising most of the WAT and IFCE/INRAE welfare indicators in semi-feral horses. Some adaptations, such as considering validation of scales, positive welfare indicators and animals' free-choice of conditions, have been suggested for future in-field application.
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The Social and Reproductive Challenges Faced by Free-Roaming Horse (Equus caballus) Stallions. Animals (Basel) 2023; 13:ani13071151. [PMID: 37048406 PMCID: PMC10093049 DOI: 10.3390/ani13071151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/10/2023] [Accepted: 03/22/2023] [Indexed: 03/30/2023] Open
Abstract
In captivity, intact male horses, due to their sexual drive, are usually socially isolated from other horses. This lifestyle strongly contrasts with that experienced by horses living in free-roaming, feral, or semi-feral conditions, where adult stallions have several roles in their social group, with successful reproduction being their primary drive. Reproductive skew in wild populations is high; many stallions will fail to reproduce at all, while others achieve high levels of reproductive success, siring a large number of foals. Successful stallions are those with particular characteristics and abilities that facilitate harem formation and tenure, allowing them to successfully take over a harem or establish a new one, protect mares from rival stallions, employ appropriate social behaviour to maintain group cohesion, and avoid kin-mating, for example through kin recognition mechanisms. Whilst the life of free-living stallions is far from stress-free, they retain ancestral adaptations to selection pressures (such as predation and competition) exhibited by their natural environment over thousands of years. Here, we discuss the challenges faced by free-living horse stallions, the roles they play in social groups, and their resulting social needs. By understanding these pressures and how stallions react to them, we highlighted the importance of the social environment for the stallion. It is hoped that a better understanding of wild stallions’ lives will lead to their needs being more clearly met in captivity, reducing stereotypical behaviour and improving welfare.
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Correction: Wiśniewska et al. Heterospecific Fear and Avoidance Behaviour in Domestic Horses (Equus caballus). Animals 2021, 11, 3081. Animals (Basel) 2022; 12:ani12162026. [PMID: 36009750 PMCID: PMC9404406 DOI: 10.3390/ani12162026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 06/30/2022] [Indexed: 11/16/2022] Open
Abstract
The authors wish to make the following correction to this paper [...]
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Social roles influence cortisol levels in captive Livingstone's fruit bats (Pteropus livingstonii). Horm Behav 2022; 144:105228. [PMID: 35772196 DOI: 10.1016/j.yhbeh.2022.105228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/03/2022] [Accepted: 06/21/2022] [Indexed: 11/16/2022]
Abstract
A critical component of conserving and housing species ex situ is an explicit scientific understanding of the physiological underpinnings of their welfare. Cortisol has been repeatedly linked to stress, and therefore used as an indicator of welfare for many species. In order to measure cortisol in the Livingstone's fruit bat (Pteropus livingstonii; a critically endangered keystone species) without disturbing the captive population, we have developed and validated a non-invasive, novel hormone extraction procedure and faecal glucocorticoid assay. A total of 92 faecal samples, 73 from the P. livingstonii breeding colony at Jersey Zoo, Channel Islands and 19 samples from P. livingstonii housed at Bristol Zoological Gardens, UK, have been collected and analyzed. Mixed-effect modelling of the influence of physiological state variables on cortisol concentration revealed that lactating females had higher cortisol levels than non-lactating females, indicating that our assay is measuring biologically relevant hormone concentrations. Males and older bats also had higher cortisol than non-lactating females and younger individuals. Further analysis applied social network methodology to compare the cortisol levels of bats with different social roles. We found that individuals that linked social groups possessed higher than average cortisol levels and conversely, individuals with high-quality, positive relationships had lower cortisol levels. These results demonstrate, for the first time in a bat species, social mediation of stress hormones. Lastly, the frequency of vocalisation was found to positively correlate with cortisol concentration in males, suggesting that this behaviour may be used by animal management as a visual indicator of a bat's hormonal status. Hence, this research has provided unique insights and empirical scientific knowledge regarding the relationship between the physiology and social behaviour of P. livingstonii, therefore allowing for recommendations to be made to optimise bat welfare at the individual level.
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Long term analysis of social structure: evidence of age‐based consistent associations in male Alpine ibex. OIKOS 2022. [DOI: 10.1111/oik.09511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Preliminary investigation of the effects of a concert on the behavior of zoo animals. Zoo Biol 2022; 41:308-327. [PMID: 35137965 PMCID: PMC9546360 DOI: 10.1002/zoo.21676] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/17/2021] [Accepted: 01/04/2022] [Indexed: 01/04/2023]
Abstract
To increase visitor footfall and engagement, zoos may host public events that may extend outside typical opening hours. With plans to hold a 2‐day concert at Tayto Park, Ireland, this study aimed to identify the behavioral response to the music event of a selected group of species in the zoo. Twenty‐two species were observed across three phases of the event (pre‐, during, and post event). Specific behaviors of interest were categorized as active, resting, asleep, abnormal, and out of sight, with repeated observations being made at each enclosure during each phase. Alongside these behavioral data, sound pressure levels (SPLs) were concurrently recorded at the observation locations in terms of both dB(A) and dB(C). The median dB(C) levels during the event were found to be significantly higher (mdn = 64.5 dB) when compared with both pre‐event (mdn = 60.7 dB) and postevent phases (mdn = 59.4 dB), while dB(A) levels were only significantly higher during the event (51.7 dB) when compared with the pre‐event phase (mdn = 49.8 dB). We found some species‐specific behavioral changes (mainly associated with active and resting behaviors) correlated with increased SPLs and/or event itself. However, the behavioral responses varied between species and there were numerous species that did not respond with any change in behavior to the increased SPLs or the event itself. This variation in response across species reinforces the need for monitoring of behavioral changes as well as consideration of their natural behavioral ecology when implementing appropriate mitigation strategies. Further research should be encouraged to provide an evidence‐based assessment of how music events may affect animal welfare and behavior and to test the efficacy of mitigation strategies that are implemented to safeguard animal welfare. We found several species expressed behavioral changes that correlated with increased noise and/or other aspects of a public event. The nature of these responses varied across species. Many species did not show any change in behavior during the event. Habitual resting/active periods may have changed due to extended opening hours. The onset of sleep behavior in vultures occurred later during the event compared with the pre‐event phase. Porcupines emerged from their dens later during the event compared to pre‐ or postevent phases. Predetermined maximum sound pressure limits for animal enclosures were not exceeded, confirming that precautionary measures, that is, soundproofing, location, stage position, and other mitigations, provided effective control of noise propagation in the zoo.
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Heterospecific Fear and Avoidance Behaviour in Domestic Horses ( Equus caballus). Animals (Basel) 2021; 11:ani11113081. [PMID: 34827813 PMCID: PMC8614530 DOI: 10.3390/ani11113081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Horses lacking exposure to cattle often show a fearful response when confronted with cows. In controlled conditions, we tested the responses towards two cows and a novel moving object in twenty horses in arena and hand-leading tests. The horses avoided the proximity of all stimuli, but of one of the cows the most. However, both cows provoked a stronger cardiac response than an inanimate object. We hypothesise that this response may be due to both neophobia and heterospecific interactions. Abstract Ridden horses have been reported to be fearful of cows. We tested whether cows could provoke behavioural and cardiac fear responses in horses, and whether these responses differ in magnitude to those shown to other potential dangers. Twenty horses were exposed to cow, a mobile object or no object. The time spent at different distances from the stimulus was measured. In a separate test, heart rate (HR), root mean square of successive differences between heartbeats (RMSSD) and the horses’ perceived fear were assessed at various distances from the stimuli. The horses avoided the area nearest to all stimuli. During hand-leading, the cow elicited the highest HR and lowest RMSSD. Led horses’ responses to the cow and box were rated as more fearful as the distance to the stimulus decreased. Mares had a higher HR than geldings across all tests. HR positively correlated with the fearfulness rating at the furthest distance from the cow and box, and RMSSD negatively correlated with this rating in cow and control conditions. Our results show that these horses’ avoidance response to cows was similar or higher to that shown towards a novel moving object, demonstrating that potentially, both neophobia and heterospecific communication play a role in this reaction.
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Evaluation of the Feasibility, Reliability, and Repeatability of Welfare Indicators in Free-Roaming Horses: A Pilot Study. Animals (Basel) 2021; 11:ani11071981. [PMID: 34359108 PMCID: PMC8300213 DOI: 10.3390/ani11071981] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/21/2021] [Accepted: 06/29/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Animal welfare assessment is an essential tool for maintaining positive animal wellbeing. Validated welfare assessment protocols have been developed for farm, laboratory, zoo, and companion animals, including horses in managed care. However, wild and free-roaming equines have received relatively little attention, despite populations being found worldwide. In the UK, free-roaming ponies inhabit areas of Exmoor, Dartmoor, and New Forest, England, and Snowdonia National Park in Wales, amongst others. Visitors and local members of the public who encounter free-roaming ponies occasionally raise concerns about their welfare, as they are not provided with additional food, water, or shelter. In this study, we evaluated the feasibility, reliability, and repeatability of welfare indicators that can be applied to a population of free-roaming Carneddau Mountain ponies to address such concerns. Our findings indicate that many of the trialed indicators were successfully repeated and had good levels of inter-assessor reliability. Reliable and repeatable welfare indicators for free-roaming and semi free-roaming ponies will enable population managers and conservation grazing schemes to manage the welfare of free-roaming horses and ponies. Abstract Validated assessment protocols have been developed to quantify welfare states for intensively managed sport, pleasure, and working horses. There are few protocols for extensively managed or free-roaming populations. Here, we trialed welfare indicators to ascertain their feasibility, reliability, and repeatability using free-roaming Carneddau Mountain ponies as an example population. The project involved (1) the identification of animal and resource-based measures of welfare from both the literature and discussion with an expert group; (2) testing the feasibility and repeatability of a modified body condition score and mobility score on 34 free-roaming and conservation grazing Carneddau Mountain ponies; and (3) testing a prototype welfare assessment template comprising 12 animal-based and 6 resource-based welfare indicators, with a total of 20 questions, on 35 free-roaming Carneddau Mountain ponies to quantify inter-assessor reliability and repeatability. This pilot study revealed that many of the indicators were successfully repeatable and had good levels of inter-assessor reliability. Some of the indicators could not be verified for reliability due to low/absent occurrence. The results indicated that many animal and resource-based indicators commonly used in intensively managed equine settings could be measured in-range with minor modifications. This study is an initial step toward validating a much-needed tool for the welfare assessment of free-roaming and conservation grazing ponies.
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Social network analysis of small social groups: Application of a hurdle GLMM approach in the Alpine marmot (
Marmota marmota
). Ethology 2021. [DOI: 10.1111/eth.13151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Social Experience of Captive Livingstone's Fruit Bats ( Pteropus livingstonii). Animals (Basel) 2020; 10:E1321. [PMID: 32751770 PMCID: PMC7460041 DOI: 10.3390/ani10081321] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/21/2020] [Accepted: 07/29/2020] [Indexed: 12/17/2022] Open
Abstract
Social network analysis has been highlighted as a powerful tool to enhance the evidence-based management of captive-housed species through its ability to quantify the social experience of individuals. We apply this technique to explore the social structure and social roles of 50 Livingstone's fruit bats (Pteropus livingstonii) housed at Jersey Zoo, Channel Islands, through the observation of associative, affiliative, and aggressive interactions over two data collection periods. We implement binomial mixture modelling and characteristic-based assortment quantification to describe the complexity and organisation of social networks, as well as a multiple regression quadratic assignment procedural (MRQAP) test to analyse the relationship between network types. We examine the effects of individual characteristics (i.e., sex, age, and dominance rank) on social role by fitting models to explain the magnitude of node metrics. Additionally, we utilize a quadratic assignment procedural (QAP) test to assess the temporal stability of social roles over two seasons. Our results indicate that P. livingstonii display a non-random network structure. Observed social networks are positively assorted by age, as well as dominance rank. The frequency of association between individuals correlates with a higher frequency of behavioural interactions, both affiliative and aggressive. Individual social roles remain consistent over ten months. We recommend that, to improve welfare and captive breeding success, relationships between individuals of similar ages and dominance levels should be allowed to persist in this group where possible, and separating individuals that interact frequently in an affiliative context should be avoided.
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Social stability in semiferal ponies: networks show interannual stability alongside seasonal flexibility. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2017.04.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
Many animals preferentially associate with certain other individuals. This social structuring can influence how populations respond to changes to their environment, thus making network analysis a promising technique for understanding, predicting, and potentially manipulating population dynamics. Various network statistics can correlate with individual fitness components and key population-level processes, yet the logical role and formal application of animal social network theory for conservation and management have not been well articulated. We outline how understanding of direct and indirect relationships between animals can be profitably applied by wildlife managers and conservationists. By doing so, we aim to stimulate the development and implementation of practical tools for wildlife conservation and management and to inspire novel behavioral research in this field.
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Personality in the cockroach Diploptera punctata: Evidence for stability across developmental stages despite age effects on boldness. PLoS One 2017; 12:e0176564. [PMID: 28489864 PMCID: PMC5425029 DOI: 10.1371/journal.pone.0176564] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 04/12/2017] [Indexed: 01/17/2023] Open
Abstract
Despite a recent surge in the popularity of animal personality studies and their wide-ranging associations with various aspects of behavioural ecology, our understanding of the development of personality over ontogeny remains poorly understood. Stability over time is a central tenet of personality; ecological pressures experienced by an individual at different life stages may, however, vary considerably, which may have a significant effect on behavioural traits. Invertebrates often go through numerous discrete developmental stages and therefore provide a useful model for such research. Here we test for both differential consistency and age effects upon behavioural traits in the gregarious cockroach Diploptera punctata by testing the same behavioural traits in both juveniles and adults. In our sample, we find consistency in boldness, exploration and sociality within adults whilst only boldness was consistent in juveniles. Both boldness and exploration measures, representative of risk-taking behaviour, show significant consistency across discrete juvenile and adult stages. Age effects are, however, apparent in our data; juveniles are significantly bolder than adults, most likely due to differences in the ecological requirements of these life stages. Size also affects risk-taking behaviour since smaller adults are both bolder and more highly explorative. Whilst a behavioural syndrome linking boldness and exploration is evident in nymphs, this disappears by the adult stage, where links between other behavioural traits become apparent. Our results therefore indicate that differential consistency in personality can be maintained across life stages despite age effects on its magnitude, with links between some personality traits changing over ontogeny, demonstrating plasticity in behavioural syndromes.
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Consistent social structure and optimal clique size revealed by social network analysis of feral goats, Capra hircus. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.01.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Vertical ordering and electronic coupling in bilayer nanoscale InAs/GaAs quantum dots separated by a thin spacer layer. NANOTECHNOLOGY 2008; 19:505704. [PMID: 19942781 DOI: 10.1088/0957-4484/19/50/505704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The vertical ordering and electronic coupling in bilayer nanoscale InAs/GaAs quantum dots separated by a thin (7-9 nm) spacer layer has been investigated by transmission electron microscopy and photoluminescence measurements. The nanoscale dots are grown by molecular beam epitaxy (MBE) at 0.028 ML s(-1) growth rate. The active dots having higher monolayer coverages showed reduced ordering due to local strain at the growth surface. Also the active dots with increased monolayer coverage is a probable cause of tunneling-assisted carrier transfer between the dot layers.
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Tunability of photoluminescence of InAS/GaAs quantum dots by growth pause introduced ripening. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2008; 8:6232-6237. [PMID: 19205188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The effect of dot ripening pause on self organized InAs/GaAs QD's grown by MBE at two different growth rates and the resulting tunability of emission properties were studied with the help of PL and AFM experiments. We found the evolution of larger coherent islands with dot-pause due to high surface mobility of the In adatoms at the growth temperature resulting in a redshift in the PL spectra. A small blue shift in the emission is observed in case of the islands grown at higher growth rate and being allowed to ripen for sufficient time due to In desorption at high growth temperature.
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Production of photocurrent due to intermediate-to-conduction-band transitions: a demonstration of a key operating principle of the intermediate-band solar cell. PHYSICAL REVIEW LETTERS 2006; 97:247701. [PMID: 17280325 DOI: 10.1103/physrevlett.97.247701] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Indexed: 05/13/2023]
Abstract
We present intermediate-band solar cells manufactured using quantum dot technology that show for the first time the production of photocurrent when two sub-band-gap energy photons are absorbed simultaneously. One photon produces an optical transition from the intermediate-band to the conduction band while the second pumps an electron from the valence band to the intermediate-band. The detection of this two-photon absorption process is essential to verify the principles of operation of the intermediate-band solar cell. The phenomenon is the cornerstone physical principle that ultimately allows the production of photocurrent in a solar cell by below band gap photon absorption, without degradation of its output voltage.
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Enhanced third-order nonlinear effects in optical AlGaAs nanowires. OPTICS EXPRESS 2006; 14:9377-9384. [PMID: 19529322 DOI: 10.1364/oe.14.009377] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report the first observation of enhanced third-order nonlinear effects in AlGaAs nanowires. AlGaAs nanowaveguides with widths varying from 100 to 600nm were fabricated and characterized. Nonlinear phase shifts of approximately pi were experimentally observed at 1.55mum with peak powers of 30-40W in 600mum long, 550nm wide guides.
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Abstract
We investigated the interaction of discrete solitons with defect states fabricated in arrays of coupled waveguides. We achieved attractive and repulsive defects by decreasing and increasing, respectively, the spacing of one pair of waveguides in an otherwise uniform array. Linear and nonlinear propagation in the same samples show distinctly different properties. The role of the Peierls-Nabarro potential in the interaction of the soliton with the defect is discussed.
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A New Method for the Production of Active Nitrogen and its Application to the Study of Collision Effects in the Nitrogen Molecular Spectrum. ACTA ACUST UNITED AC 2002. [DOI: 10.1088/0370-1298/67/9/310] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Quantum bits (qubits) are the fundamental building blocks of quantum information processors, such as quantum computers. A qubit comprises a pair of well characterized quantum states that can in principle be manipulated quickly compared to the time it takes them to decohere by coupling to their environment. Much remains to be understood about the manipulation and decoherence of semiconductor qubits. Here we show that hydrogen-atom-like motional states of electrons bound to donor impurities in currently available semiconductors can serve as model qubits. We use intense pulses of terahertz radiation to induce coherent, damped Rabi oscillations in the population of two low-lying states of donor impurities in GaAs. Our observations demonstrate that a quantum-confined extrinsic electron in a semiconductor can be coherently manipulated like an atomic electron, even while sharing space with approximately 10(5) atoms in its semiconductor host. We anticipate that this model system will be useful for measuring intrinsic decoherence processes, and for testing both simple and complex manipulations of semiconductor qubits.
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Quasi phase matching in GaAs--AlAs superlattice waveguides through bandgap tuning by use of quantum-well intermixing. OPTICS LETTERS 2000; 25:1370-1372. [PMID: 18066220 DOI: 10.1364/ol.25.001370] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report the observation of second-harmonic generation by type I quasi phase matching in a GaAs-AlAs superlattice waveguide. Quasi phase matching was achieved through modulation of the nonlinear coefficient chi((2))(zxy), which we realized by periodically tuning the superlattice bandgap. Second-harmonic generation was demonstrated for fundamental wavelengths from 1480 to 1520 nm, from the third-order gratings with periods from 10.5 to 12.4microm . The second-harmonic signal spectra demonstrated narrowing owing to the finite bandwidth of the quasi-phase-matching grating. An average power of ~110 nW was obtained for the second harmonic by use of an average launched pump power of ?2.3mW .
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Abstract
Few studies exist on female sexual offenders or women accused of sexual offenses. In some instances, conclusions from existing studies conflict. In an effort to better understand the phenomenon of sexual abuse by females, we gathered data on all women charged with a sexual offense referred to our facility (William S. Hall Psychiatric Institute in Columbia, South Carolina) for a criminal responsibility/competence to stand trial evaluation from 1987 to 1997. Alleged sexual offenses included criminal sexual conduct one, two, and three and performing a lewd act upon a minor. Fifteen women were referred. This study examines characteristics of the accused women and their victims. Patterns of the alleged offenses and outcome of forensic evaluation are also examined. We found women accused of committing sexual offenses to have a high likelihood of past sexual and physical victimization as well as ongoing physical victimization. Borderline intellectual function and mental retardation were common and women acted frequently with co-defendants. The victims knew the perpetrator in every instance.
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Optoelectronic Systems Based on InGaAs- Complementary-Metal-Oxide-Semiconductor Smart-Pixel Arrays and Free-Space Optical Interconnects. APPLIED OPTICS 1998; 37:2822-2830. [PMID: 18273228 DOI: 10.1364/ao.37.002822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Free-space optical interconnects have been identified as a potentially important technology for future massively parallel-computing systems. The development of optoelectronic smart pixels based on InGaAs/AlGaAs multiple-quantum-well modulators and detectors flip-chip solder-bump bonded onto complementary-metal-oxide-semiconductor (CMOS) circuits and the design and construction of an experimental processor in which the devices are linked by free-space optical interconnects are described. For demonstrating the capabilities of the technology, a parallel data-sorting system has been identified as an effective demonstrator. By use of Batcher's bitonic sorting algorithm and exploitation of a perfect-shuffle optical interconnection, the system has the potential to perform a full sort on 1024, 16-bit words in less than 16 mus. We describe the design, testing, and characterization of the smart-pixel devices and free-space optical components. InGaAs-CMOS smart-pixel, chip-to-chip communication has been demonstrated at 50 Mbits/s. It is shown that the initial system specifications can be met by the component technologies.
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Observation of Plasmon-Optic Phonon Coupled Modes in GaAs/AlGaAs Resonant Tunneling Structures via Acoustic Phonon Decay Products. PHYSICAL REVIEW LETTERS 1995; 75:1827-1830. [PMID: 10060401 DOI: 10.1103/physrevlett.75.1827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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