Quantum Nonlinear Optics with a Germanium-Vacancy Color Center in a Nanoscale Diamond Waveguide.

We demonstrate a quantum nanophotonics platform based on germanium-vacancy (GeV) color centers in fiber-coupled diamond nanophotonic waveguides. We show that GeV optical transitions have a high quantum efficiency and are nearly lifetime broadened in such nanophotonic structures. These properties yield an efficient interface between waveguide photons and a single GeV center without the use of a cavity or slow-light waveguide. As a result, a single GeV center reduces waveguide transmission by 18±1% on resonance in a single pass. We use a nanophotonic interferometer to perform homodyne detection of GeV resonance fluorescence. By probing the photon statistics of the output field, we demonstrate that the GeV-waveguide system is nonlinear at the single-photon level.

Lateralized antennal control of aggression and sex differences in red mason bees, Osmia bicornis.

Comparison of lateralization in social and non-social bees tests the hypothesis that population-level, directional asymmetry has evolved as an adjunct to social behaviour. Previous research has supported this hypothesis: directional bias of antennal use in responding to odours and learning to associate odours with a food reward is absent in species that feed individually, such as mason bees, whereas it is clearly present in eusocial honeybees and stingless bees. Here we report that, when mason bees engage in agonistic interactions, a species-typical interactive behaviour, they do exhibit a directional bias according to which antenna is available to be used. Aggression was significantly higher in dyads using only their left antennae (LL) than it was in those using only their right antennae (RR). This asymmetry was found in both males and females but it was stronger in females. LL dyads of a male and a female spent significantly more time together than did other dyadic combinations. No asymmetry was present in non-aggressive contacts, latency to first contact or body wiping. Hence, population-level lateralization is present only for social interactions common and frequent in the species' natural behaviour. This leads to a refinement of the hypothesis linking directional lateralization to social behaviour.

Spectroscopy of surface-induced noise using shallow spins in diamond.

We report on the noise spectrum experienced by few nanometer deep nitrogen-vacancy centers in diamond as a function of depth, surface coating, magnetic field and temperature. Analysis reveals a double-Lorentzian noise spectrum consistent with a surface electronic spin bath in the low frequency regime, along with a faster noise source attributed to surface-modified phononic coupling. These results shed new light on the mechanisms responsible for surface noise affecting shallow spins at semiconductor interfaces, and suggests possible directions for further studies. We demonstrate dynamical decoupling from the surface noise, paving the way to applications ranging from nanoscale NMR to quantum networks.

Indistinguishable photons from separated silicon-vacancy centers in diamond.

We demonstrate that silicon-vacancy (SiV) centers in diamond can be used to efficiently generate coherent optical photons with excellent spectral properties. We show that these features are due to the inversion symmetry associated with SiV centers. The generation of indistinguishable single photons from separated emitters at 5 K is demonstrated in a Hong-Ou-Mandel interference experiment. Prospects for realizing efficient quantum network nodes using SiV centers are discussed.

Multiple intrinsically identical single-photon emitters in the solid state.

Emitters of indistinguishable single photons are crucial for the growing field of quantum technologies. To realize scalability and increase the complexity of quantum optics technologies, multiple independent yet identical single-photon emitters are required. However, typical solid-state single-photon sources are inherently dissimilar, necessitating the use of electrical feedback or optical cavities to improve spectral overlap between distinct emitters. Here we demonstrate bright silicon vacancy (SiV(-)) centres in low-strain bulk diamond, which show spectral overlap of up to 91% and nearly transform-limited excitation linewidths. This is the first time that distinct single-photon emitters in the solid state have shown intrinsically identical spectral properties. Our results have impact on the application of single-photon sources for quantum optics and cryptography.

Strength of hand preference and dual task performance by common marmosets.

Study of avian and piscine species has shown that animals with stronger lateralization of the brain are able to perform two tasks presented simultaneously better than can animals with weaker lateralization. We investigated whether this might apply also to primates by testing common marmosets to see whether there is a relationship between the strength of hand preference, as an indicator of strength of brain lateralization, and the ability to carry out two tasks simultaneously. A model predator was introduced into the testing room while the marmoset was foraging. Marmosets with stronger hand preferences detected the 'predator' after shorter latency than those with weaker hand preferences. Furthermore, the marmosets with stronger hand preferences produced more mobbing (tsik) vocalizations when they reacted to the predators than did those with weaker hand preferences. There was no such association between hand preference and either latency to respond to the predator or mobbing reaction when the marmosets were not foraging at the time the predator was introduced. Hence, strength of lateralization is associated with the ability to perform foraging and predator detection simultaneously. These results are discussed with reference to the evolution of brain lateralization.

Cortisol levels in hair reflect behavioural reactivity of dogs to acoustic stimuli.

Cortisol levels in hair samples were examined in fourteen domestic dogs and related to the dogs' responses to different acoustic stimuli. Stimuli were playbacks of species-typical vocalizations recorded during three different situations ("disturbance", "isolation" and "play" barks) and the sounds of a thunderstorm. Hair samples were collected at 9:00 h and 17:00 h two weeks after the behavioural tests. Results showed that behavioural reactivity to playback of the various stimuli correlates with cortisol levels in hair samples collected at 9:00 h, and the same was the case for the separate measures of behaviour (i.e. hiding, running away, seeking attention from the tester, panting and lowering of the body posture). Hence, levels of cortisol in hair appear to reflect the dog's chronic state of emotional reactivity, or temperament.

Oxalate nephropathy in a laboratory colony of common marmoset monkeys (Callithrix jacchus) following the ingestion of Eucalyptus viminalis.

Seven common marmoset monkeys (Callithrix jacchus) from a laboratory colony of 17 died over a period of eight months. Death of six of these monkeys was attributed to kidney failure from an oxalate-induced nephropathy. The epidemiology of this outbreak suggested an exogenous source and there was strong evidence that the source was bark and leaves from an Eucalyptus viminalis tree. Branches of this tree were introduced one month before the first death. The branches were removed one month after deaths commenced, but deaths continued for another five months. Urinalysis of all surviving marmosets at 80 and 122 days after initial contact with the E viminalis branches suggested that these monkeys had renal impairment. In the cases described here, the eating behaviour of common marmosets apparently exposed the animals to toxic levels of oxalate in the bark and leaves of an E viminalis tree.

Perception of biological motion in common marmosets (Callithrix jacchus): by females only.

The ability to perceive biological motion (BM) has been demonstrated in a number of species including humans but the few studies of non-human primates have been relatively inconclusive. We investigated whether common marmosets (Callithrix jacchus) are able to perceive biological motion, using a novel method to test non-human primates. Marmosets (7 male and 7 female) were trained to remove a cover from a container and look inside it, revealing a computer screen. Then they were presented with images on this computer screen consisting of a novel BM pattern (a walking hen) and 4 manipulations of that pattern (a static frame of this pattern and inverted, scrambled, and rotating versions of the pattern). The behavioural responses of the marmosets were recorded and used to assess discrimination between stimuli. BM was attended to by females but not males, as shown by active inspection behaviour, mainly movement of the head towards the stimulus. Females paid significantly less attention to all of the other stimuli. This indicates the females' ability to attend to biological motion. Females showed slightly more attention to the inverted BM than to the static, scrambled, and rotating patterns. The males were less attentive to all of the stimuli than were the females and, unlike the females, responded to all stimuli in a similar manner. This sex difference could be due to an inability of males to recognise BM altogether or to a lesser amount of curiosity. Considered together with the findings of previous studies on chicks and humans, the results of the present study support the notion of a common mechanism across species for the detection of BM.

Is there a role for adjuvant hysterectomy after suboptimal concurrent chemoradiation in cervical carcinoma?

AIMS: Failure to carry out intracavitary brachytherapy (ICBT) in cervical carcinoma results in suboptimal chemoradiation and increases the risk of recurrence. The aim of this study was to investigate the role of adjuvant hysterectomy after unsuccessful ICBT. MATERIALS AND METHODS: A retrospective analysis was carried out of all women referred with cervical carcinoma between January 1999 and July 2007 where ICBT insertion was unsuccessful after the initial chemoradiation. The data collected and analysed included histology, stage of disease, causes for unsuccessful ICBT insertion, the response to the initial chemoradiation, subsequent treatment, morbidity, recurrence rates and survival rates. Kaplan-Meier and Log-rank methods were used to analyse recurrence-free and overall survival rates. RESULTS: ICBT insertion was unsuccessful in 19 of 208 (9%) patients. The causes of failure were: inability to dilate the cervix; uterine perforation; vesicovaginal fistula; patient refusal; other problems, including the presence of pyometrium, patient not fit for general anaesthetic, and narrow vagina; and consultant choice with no obvious reason. Fourteen of 19 patients (74%) received further pelvic external beam radiotherapy (EBRT) alone; five (26%) patients underwent adjuvant hysterectomy. The median follow-up for all patients was 63 months; 60 months for patients treated with adjuvant hysterectomy (range 31-68 months) and 85 months for patients treated with further EBRT. None of the patients treated with adjuvant hysterectomy developed any significant late toxicity. Seven patients (50%) treated with EBRT have relapsed compared with none in the adjuvant hysterectomy arm (P=0.068). Six patients (43%) in the EBRT arm have subsequently died of recurrent disease compared with none in the adjuvant hysterectomy arm (P=0.152). CONCLUSIONS: Adjuvant hysterectomy after unsuccessful ICBT does not seem to increase late toxicity and reduces the risk of pelvic recurrence and may improve survival. The role of adjuvant hysterectomy after suboptimal chemoradiation merits further investigation in clinical trials.

Low temperature studies of the excited-state structure of negatively charged nitrogen-vacancy color centers in diamond.

We report a study of the 3E excited-state structure of single negatively charged nitrogen-vacancy (NV) defects in diamond, combining resonant excitation at cryogenic temperatures and optically detected magnetic resonance. A theoretical model is developed and shows excellent agreement with experimental observations. In addition, we show that the two orbital branches associated with the 3E excited state are averaged when operating at room temperature. This study leads to an improved physical understanding of the NV defect electronic structure, which is invaluable for the development of diamond-based quantum information processing.

Visual lateralization and development of spatial and social spacing behaviour of chicks (Gallus gallus domesticus).

We investigated whether the development of spatial behaviour of the domestic chicken is influenced by light exposure of the embryo, as is known to be the case for some other lateralized visual functions. Ninety-six chicks were incubated in the dark or exposed to light during the final days of incubation. Half of the chicks in each group had the experience of moving behind opaque screens from 10 to 12 days of age. The other half were given transparent screens as a control. Chicks were tested in a detour test and a rotated floor test and their dispersal in groups was observed in larger pens. In the rotated floor test, chicks that had had experience with opaque screens used distal cues significantly more often than chicks that had experience with transparent screens (P=0.042), regardless of whether they had been exposed to light before hatching or incubated in the dark. There were no significant differences between treatments in the detour test or in the dispersal behaviour. Hence, visual lateralization has no influence on the development of the spatial behaviour that we tested, whereas the occlusion experience is quite specific and results in shifted attention to distal spatial cues.

Contact calls of common marmosets (Callithrix jacchus): influence of age of caller on antiphonal calling and other vocal responses.

Marmosets, as do many other primates, live in forest environments, are group living and constantly at risk of predation. Retaining contact with one another is therefore a matter of survival. We ask here whether their contact calls (phee and twitter vocalizations) are in some way ordered acoustically by sex or age and whether the calls of older marmosets elicit different responses than those of younger marmosets. In our study, marmosets (2-14 years) were visually isolated from conspecifics and the vocal responses to each isolated caller by other marmosets in the colony were recorded. Vocal responses to phee calls largely consisted of phee calls and, less commonly, twitter calls. No differences between the responses to calls by males and females were apparent. However, we found a strong positive and significant correlation between the caller's age and the percentage of its phee calls receiving a phee response, and a significant negative correlation between the caller's age and the percentage of its phee calls receiving a twitter response. The older the marmoset, the more antiphonal calling occurred. Two-syllable phee calls were emitted more often by older marmosets (10-14 years) than by younger ones (2-6 years). Hence, we have found age-dependent differences in phee-call production and a consistent change in the response received across the adult life-span. This age-dependent effect was independent of kinship relations. This is the first evidence that marmosets distinguish age by vocal parameters alone and make social decisions based on age.

Asymmetry of flight and escape turning responses in horses.

We investigated whether horses display greater reactivity to a novel stimulus presented in the left compared to the right monocular visual field, and whether a population bias exists for escape turning when the same stimulus was presented binocularly. Domestic horses (N=30) were tested on three occasions by a person opening an umbrella five metres away and then approaching. The distance each horse moved away before stopping was measured. Distance was greatest for approach on the left side, indicating right hemisphere control of flight behaviour, and thus followed the same pattern found previously in other species. When order of monocular presentation was considered, an asymmetry was detected. Horses tested initially on the left side exhibited greater reactivity for left approach, whereas horses tested on the right side first displayed no side difference in reactivity. Perhaps left hemisphere inhibition of flight response allowed horses to learn that the stimulus posed no threat and this information was transferred to the right hemisphere. No population bias existed for the direction of escape turning, but horses that turned to the right when approached from the front were found to exhibit longer flight distances than those that turned to the left.

Light experience and the development of behavioural lateralization in chicks III. Learning to distinguish pebbles from grains.

Chicks searching for food grains against a background of unfamiliar pebbles usually peck pebbles less when using the right eye (RE), or both eyes, than when using the left eye (LE), provided that the embryo's RE has been exposed to light (Li), as is normal. When pecking is fast this right/left difference is mainly due to a heightened ability of RE chicks to inhibit premature pecks (and inappropriate responses in general). Dark incubation (Da) abolishes this ability in RE chicks, and RE and LE chicks show similar frequent pebble pecks. We show now that, under conditions that cause cautious pecking, both Li and Da chicks show a new effect: in both cases LE chicks peck pebbles more than RE chicks, probably because of the novelty of pebbles. Interest in novelty in LE chicks is known to be unaffected by light in incubation. Age-dependent effects are also important. RE and LE chicks, which had either the LE or RE exposed to light before hatching, were tested on days 3, 5, 8 or 12 post-hatching, under conditions giving normal fast pecking. Artificial exposure of the embryo's LE to light reversed the lateralization: in general, chicks using the light-exposed eye performed well at all ages. Irrespective of which eye system had heightened ability to inhibit pebble pecks, RE performance differed from usual on 2 days, whereas LE chicks showed no age-dependent changes. Changes confined to the RE system, therefore, affect behaviour independently of lateralization of the ability to inhibit inappropriate response.

Relationship between paw preference strength and noise phobia in Canis familiaris.

The authors investigated the relationship between degree of lateralization and noise phobia in 48 domestic dogs (Canis familiaris) by scoring paw preference to hold a food object and relating it to reactivity to the sounds of thunderstorms and fireworks, measured by playback and a questionnaire. The dogs without a significant paw preference were significantly more reactive to the sounds than the dogs with either a left-paw or right-paw preference. Intense reactivity, therefore, is associated with a weaker strength of cerebral lateralization. The authors note the similarity between their finding and the weaker hand preferences shown in humans suffering extreme levels of anxiety and suggest neural mechanisms that may be involved.

Behavioural lateralisation in the Australian magpie (Gymnorhina tibicen).

In many vertebrates, the brain is lateralised such that each hemisphere is specialised to serve specific functions. This may translate into lateralisation in behaviour through preferential use of receptors or appendages associated with a particular hemisphere (e.g., handedness) or in differential responses to stimuli perceived on the animal's left or right side. In this study, we investigated behavioural laterality in the Australian magpie, Gymnorhina tibicen. We found that, while the birds did not have a population bias for one antipredator behaviour (visual inspection of an approaching human), there were biases for another (alarm calling); those birds that used their left eye more relative to their right eye gave alarm calls more frequently. We also observed that juvenile birds begged for food on the right side of parents significantly more frequently than on the left side. These trends are consistent with trends in behavioural laterality that have been recorded in captive and lab-reared species. Ours is one of the few studies to observe patterns of laterality in a wild species.

Pre- and post-hatching effects of corticosterone treatment on behavior of the domestic chick.

We investigated the effect of 60 ìg of corticosterone administered to domestic chicks either before or after hatching on the behavioral response to isolation in a novel arena and performance in a task involving the simultaneous identification of food and detection of a predator (overhead silhouette of a hawk moving overhead). Following release into a novel arena, chicks treated with corticosterone at 18 days of incubation emitted more distress vocalizations. In contrast, no difference in the number of vocalizations was found between chicks treated with corticosterone at day 1 post-hatching and controls. Behavior in the home cages was generally similar across treatments, though chicks treated with corticosterone at 18 days of incubation slept more than control chicks. While searching for grain against a background of pebbles, chicks treated with corticosterone at embryonic day 18, but not chicks treated on day 1 post-hatching, took longer to detect the overhead image of a predator than did controls. Corticosterone treatment at both ages increased the rate of pecking at grains and pebbles. Our findings support work on other birds indicating that corticosterone treatment during incubation influences stress reactivity. The impairment in predator detection in chicks treated with corticosterone on day 18 of incubation appears to be caused by the known effects of corticosterone treatment at this age in preventing the development of lateralization of the thalamofugal visual projections. This further supports the hypothesis that brain lateralization provides an advantage in performing more than one task simultaneously.

Mobbing vocalizations as a coping response in the common marmoset.

Using a non-invasive method of sampling saliva followed by assay for cortisol levels, we found that common marmosets (Callithrix jacchus) show a decrease in cortisol levels after seeing a snake-model stimulus that reliably elicits mobbing (tsik) calls. In fact, there was a significant positive correlation between the number of tsik vocalizations made and the magnitude of the decrease in the cortisol concentrations. Furthermore, marmosets with higher levels of cortisol prior to being exposed to the stimulus produce more tsik calls than those with lower levels of cortisol. Subsequent experiments showed that, in response to 15 min of isolation with no visual or auditory contact with conspecifics (a traditional stressor), cortisol levels increased significantly. However, playback of the mobbing calls of a familiar conspecific to individual isolated marmosets not only prevented the rise in cortisol, but also actually caused a decrease in the levels of this hormone. This suggests that the mobbing calls serve to calm the marmoset after experiencing a stressful situation. This finding results in a greater understanding as to the role of physiological responses during communication in this species and could have implications for the welfare of marmosets in captivity.

Hemispheric specialization and dual processing in strongly versus weakly lateralized chicks.

Lateralization of various functions is well established in the domestic chick and other vertebrates. The function of lateralization is a question under investigation now. In a previous study, it was shown that chicks incubated in the dark (Da), which prevents the development of lateralization of visual foraging and predator detection, did not perform well when two tasks requiring simultaneous use of the expertise of the right and left eye systems were presented. Performance of a task requiring the chick to find grains against a background of pebbles deteriorated in the Da chicks in the presence of a predator. In the study reported here, the two simultaneous tasks were tested in both binocular and monocular conditions to establish the role of each eye system. Learning of the pebble-floor task was poor in Da chicks tested binocularly or monocularly and in the light-exposed (Li) chicks using the left eye (LE). The time taken to complete the pebble-floor task in the presence of a predator was significantly longer for the Da chicks. This was because pecking was interrupted for longer times when the predator was presented, and the Da chicks made more distress calls than the Li. The latency to detect the predator was longest in the Li chicks using the right eye (RE) (i.e., the Li were lateralized). In the Li chicks, sustained initial viewing of the predator was by the LE. There was no LE/RE difference in the Da chicks. The intensity of responses decreased with continued presentation of the predator but forced use of the RE slowed this habituation. Exposure to light before hatching affects lateralization of both learning of the pebble-floor task and the detection of an overhead predator. Attending to the foraging and predator vigilance tasks simultaneously is impaired in the Da chicks and the superior ability of Li (lateralized) chicks is due to a specific effect of light stimulation of the RE prior to hatching. We have shown that superior performance on the dual task results from the ability to allocate food searching to one hemisphere (left) and predator vigilance to the other (right) hemisphere, achieved only by Li chicks.