Assessing lung aeration using ultrasound after birth in near-term lambs at risk of respiratory distress.

Background: Optimizing respiratory support after birth requires real-time feedback on lung aeration. We hypothesized that lung ultrasound (LUS) can accurately monitor the extent and progression of lung aeration after birth and is closely associated with oxygenation. Methods: Near-term (140 days gestation, term ∼147 days), spontaneously breathing lambs with normal (controls; n = 10) or elevated lung liquid levels (EL; n= 9) were delivered by Caesarean section and monitored for four hours after birth. LUS (Phillips CX50, L3-12 transducer) images and arterial blood gases were taken every 5-20 min. LUS images were analyzed both qualitatively (grading) and quantitatively (using the coefficient of variation of pixel intensity (CoV) to estimate the degree of lung aeration), which was correlated with the oxygen exchange capacity of the lungs (Alveolar-arterial difference in oxygen; AaDO2). Results: Lung aeration, measured using LUS, and the AaDO2 improved over the first 4 h after birth. The increase in lung aeration measured using CoV of pixel intensity, but not LUS grade, was significantly reduced in EL lambs compared to controls (p = 0.02). The gradual decrease in AaDO2 after birth was significantly correlated with increased lung aeration in both control (grade, r2 = 0.60, p < 0.0001; CoV, r2 = 0.54, p < 0.0001) and EL lambs (grade, r2 = 0.51, p < 0.0001; CoV, r2 = 0.44, p < 0.0001). Conclusions: LUS can monitor lung aeration and liquid clearance after birth in spontaneously breathing near-term lambs. Image analysis techniques (CoV) may be able detect small to moderate differences in lung aeration in conditions with lung liquid retention which are not readily identified using qualitative LUS grading.

Activity behavior of goitered gazelles in an arid environment.

The daily activity pattern in ruminants consists mainly of alternating foraging with bouts of resting, while other behaviors usually play a minor role in the daily activity budgets of ungulates most of the year. Interactions of both intrinsic and extrinsic factors force animals to adopt compromises to form optimal time proportions for foraging and resting to satisfy their daily energy demands. This paper considers the impact of ambient temperature, pasture conditions, body-size, and the effects of lactation and animal growth on the daily activities of goitered gazelles (Gazella subgutturosa). My study found: 1) temperature was the most significant factor leading to the greatest daily hour-to-hour variations in activity, as well as significant monthly changes in activity fluctuations; 2) seasonal improvement of forage conditions did not have a distinctive effect on daily activity; 3) the effect of body size, lactation and fawn growth also did not noticeably change activity fluctuations; but 4) factors related to hiding behavior had a significant impact on goitered gazelle activity. Though goitered gazelles are a sexually dimorphic species, they did not demonstrate any significant deviation between males and females in their daily activities in contrast to typical dimorphic ruminants. The goitered gazelles' hiding behavior may provide a possible explanation for this distinction, as other previously observed dimorphic ungulates were mainly species where fawns followed their mothers from birth. Among other influences, ambient temperature and features of their hiding behavior were the most significant factors influencing diurnal activity of goitered gazelles, while age and sex had a weaker impact on daily behaviors.

Female-female aggression in goitered gazelles: the desire for isolation.

In contrast to males, which compete with other males for access to mates, females compete with each other for forage-rich sites, birthing grounds, comfortable resting places, and access to sources of water and salt licking locations. This behavior has been observed in many species. However, many agonistic interactions between females occur where resources are not immediately at stake, and the reasons for their rivalry are often unclear. Therefore in this paper, I want to analyze the main causes of female-female aggression in the yearly cycle of goitered gazelles. I found that adult females had conflicts moistly with sub-adult females and less with other adult females; and these behaviors were observed mainly in May, with less in June, and only a few cases displayed during the rest of the year. The months of May-June had the most abundant and highest quality forage of the year, when competition for resources would seem to be least expected. Struggles for resting places occurred throughout the entire year, with only some bias for May that did not represent a primary level of aggression. In reality, the high rate of female-female aggressive interactions was related to the protection of birthing grounds, where mothers isolated themselves to give births, establish a strong selective mother-young bonds, keep their hiding fawns separated from alien offspring (having initial problems with distant visual recognition), and protect them against disturbance from all other females, which can undermine a fawn's hidden status and make it more vulnerable to predation.

Diversity of risk assessment patterns in antipredator behavior of goitered gazelles.

In predator-prey encounters, risk assessment and threat identification are particularly important aspects in the prey's decision in how, when and where to escape. Previous studies devoted to this topic investigated mostly factors influencing risk perception by a prey animal and on its decision when to flee; however, information on the diversity of risk assessment displays is still very limited. Therefore in this paper, I considered various display types of risk assessments and the circumstances under which they were performed. I found that the contagious effect of alarm behavior among conspecifics and the investigative approach toward the threat were the types of risk assessment found most often, while mobbing was observed least often. Every type of risk assessment had a specific usage according to the sort of suspicious object and the prey's display circumstances. Adult females with few exceptions demonstrated threat assessment behavior most often, while adult males displayed assessment behavior less frequently; in all cases, sub-adults and fawns showed these patterns significantly less often than adults. Antipredator strategy of adult females likely differed from males. Adult females had the highest response and sensitivity to any kind of potential threat and a high rate of vigilance, including risk assessment, likely related to the responsibility of rearing young. In contrast, adult males were busy mostly with social vigilance and monitored conspecifics more than predators. Adolescents and fawns showed the lowest rate of risk assessment, most likely because information on the potential risk of threat was not as useful to them since they did not have enough experience to recognize and avoid predators; instead of relying on their own experience, younger animals followed and repeated the behaviors of adults. As a result, young of many ungulate species typically have the highest losses from predation and adult females the lowest, with adult male deaths in between. This regularity was also likely true for the risk assessment behaviors of goitered gazelles in my study.

Vigilance, staring and escape running in antipredator behavior of goitered gazelle.

Predation is a very powerful force that shapes many ungulate traits. It is widely known that increasing vigilance intensity is costly and leads to a decline of forage intake. Consequently, ungulates gather into larger groups to reduce an individual vigilance burden by using the "many eyes" effect and to enhance their survival through the "safety in numbers" effect. Vigilance rate and related aggregation changes are two of the most discussed antipredator responses of ungulates to predation risk, but less considered factors also have a significant impact. To enhance our knowledge on these impact factors, I investigated the antipredator responses (vigilance, staring, and escape running) of goitered gazelles. I found that: a) adult females demonstrated vigilance, staring and escape running significantly more often than adult males, sub-adults and fawns; b) adult gazelles (females and males), having more experience in responding to threats, were more vigilant than young individuals (sub-adults and fawns), having likely more involvement in finding food; c) during the birthing and hiding periods, mothers displayed higher rates of vigilance than in other seasons, while staring and escape running were observed most often at the end of the hiding period, when fawns altering their hiding strategy to following one, started to walk a lot in the absence of mothers, as well; and d) goitered gazelles changed their vigilance rate in response to predation risks before changing group size. The events of the yearly biological cycle (birthing/rearing young for females; rutting for males) also had significant impacts on the antipredator responses (vigilance rate and aggregation) in adult gazelles.

Alarm signals in goitered gazelle with special reference to stotting, hissing and alarm urination-defecation.

Compared to solitary species, social ungulates benefit from living in groups not only because of the "many eyes effect", when each individual devotes less time to vigilance and spends more time foraging and engaged in other activities, or of the "dilution effect", when the probability that any specific individual will be caught decreases with herd size, but also because of early alarm signals produced by conspecifics that provide enough time for a successful escape from predator attack. These signals can contain multiple messages about the category of the predator and the degree of risk. Among them, stotting, alarm calls and alarm urination-defecation acts are distinctive channels of prey-predator and/or prey-prey communications. However, stotting gaits and alarm vocalizations are still subjects of numerous debates on their functionality and to whom they are addressed (predator or conspecifics); in addition, alarm urination-defecation is known for a few ungulate species and until now functional significance of this behavior has stayed elusive. I found that stotting and hissing were used by adult females significantly more often than adult males, and that they displayed these behaviors most often at the end of the hiding period and from 2 to 3 months thereafter. Stotting and alarm hissing are likely mainly used to address conspecifics as well as being used by females to warn and manage their fawns in dangerous situations and to teach them to avoid being preyed upon during the initial time after the hiding period. In contrast, alarm urination-defecation acts were displayed by females and males equally and apart of being pure physiological functions and/or a release the stress from encountering a predator, they likely also had significance as an alarm signal, though this association is poorly explored and needs further investigation.

The use of tail-flagging and white rump-patch in alarm behavior of goitered gazelles.

Tail signals and rump patch exposure in ungulates are well-documented phenomena, but there is no consensus about their functional significance, which has remained disputed. In addition, these patterns have been analyzed for only a limited number of ungulate species; and until now did not include goitered gazelles. This paper, then, will discuss these aspects of goitered gazelle antipredator behavior. I chose human harassments as predator threats and found that tail-flagging, stotting and presentation of the white rump-patch were displayed mostly by adult females, less often by adult males, and least in sub-adults. Adult females used tail-flagging and rump-patch exposure primarily for communication with their fawns especially frequently in July when fawns finished their hiding period. In August, adult females further strengthened their alarm signals by frequent stotting. Unlike females, adult males displayed tail- flagging and stotting quite randomly over months, likely depending on frequencies of encountered threats. However, females and males both displayed tail-flagging significantly more frequently than stotting (with a few exceptions) suggesting that tail-flagging has an independent communicative function, even if one signal amplifies the other. Goitered gazelles used tail-flagging and white rump-patch exposure likely as an alarm and cohesive signal for conspecifics, and adult females communicated by these signals mostly with their fawns.

Escaping behavior in goitered gazelle.

Prey species modify their behaviors in response to predation risks to minimize their vulnerability and enhance their survival. When a predation risk arises, gregarious, open-habitat-dwelling ungulates usually increase their vigilance rate and enlarge their herd sizes, which are the two antipredator responses that are most often investigated. However, other reactive responses, as well as prey risk assessments and escape strategies depending on a predator's approach behavior, are less explored. In this paper I want to discuss the responses of goitered gazelles and their escape strategies when they encountered humans or vehicles in their natural habitat in Kazakhstan. I found that in most cases adult goitered gazelles, being more experienced and habituated to dangerous situations, usually made a preflight risk assessment and stopped in mid escape for an additional scan of their surroundings. The younger, more reactive individuals behaved this way less often and instead ran immediately instead regardless of threat level. In cases with a more obvious, direct danger, all goitered gazelles, irrespective of age, galloped immediately without stopping, and ran mainly in a sideways direction almost perpendicular to or even across the path of the approaching predator. Goitered gazelles also preferred to run upward to elevated points or toward mountain foothills, where they could get higher than the perceived threat. Furthermore, this study has shown that the goitered gazelles, preferring rough open terrain of lowlands and foothills, combined escape features found in typical antipredator strategies of both open-habitat antelopes (first assessment of danger mainly through sight, then galloping to outrun the predator) and mountain-dwelling ungulates (use of rough terrain as refuge, running to the highest elevation for a better view, and attempting to get higher on the slope than their pursuer). The goitered gazelles, however, did not demonstrate any freezing pattern for concealment, typical for forest-dwelling ungulates.

Development of juvenile goitered gazelle social behavior during the hiding period.

In many ungulate species, social organization of adults is based on a linear dominance hierarchy, which in turn often positively correlates with age, body mass, and horn/antler size. In contrast to the social behavior of adults and specific mother-offspring interactions, the process of ungulate socialization in juveniles through contacts with other conspecifics is poorly understood, especially for hider species during their initial hiding period. Therefore, we investigated this process in goitered gazelle (Gazella subgutturosa), which is a typical hiding species, and analyzed all contacts between fawns and other conspecifics, omitting mother-young interactions, which are different by nature from other contacts and demands separate consideration. We found that apart from mothers, fawns interacted most often with nonmaternal adult females, less with other fawns and least with adult males and sub-adults. The frequency of the fawns' contacts with conspecifics other than their mother increased during May and early-June, reaching a maximum in late-June, when fawns had the most mobility and independence from their mothers. This frequency decreased in July, when fawns spent more time with their mothers and when they mostly followed the mother's behavior. The interactions of adult males and sub-adults of both sexes with fawns were the most aggressive in character, involving frequent displays of butting and chasing. Aggressive interactions were fewer between adult females and fawns, while fawn-fawn interactions had least aggressive displays. The main cause of interactions between fawns and other conspecifics were attempts of these young gazelles to suckle from other adults and sub-adults, especially frequently from nonmaternal females. Only fawn-fawn contacts were not linked to suckling and seemed to relate mostly to the development of social behavior and dominance hierarchies.

Mother-young recognition in goitered gazelle during hiding period.

The mother-young recognition process is crucial for the growth and survival of progeny. In "follower" ungulate species, vocal and visual cues have been found to play a leading role in the mother-young identification process from the first days postpartum, with olfactory cues also important in establishing the initial selective mother-young bond immediately after birth. In "hider" species, however, much less has been documented of mother-young recognition behaviors, especially in their natural habitat. In this paper, we investigated this process in goitered gazelle (Gazella subgutturosa), a typical hider species, in its native environment in Kazakhstan. Over the course of our study period, we investigated the behaviors of 257 females with twins and 158 females with singles through visual observations. We found that within the first month after birth, when females spend only a short time with their young, mothers recognized their fawns using mostly olfactory cues, while vision was used to locate their hiding offspring. Fawns vocalized very rarely, producing only distress calls that did not seem intended for individual identification. Licking of young by their mothers was observed frequently, not only during the first week after birth, when this action was very important for fawn stimulation for a number of physiological functions, but for several weeks after (until one month of age), when licking lost its physiological importance and likely became more of a recognition procedure. Fawns did not recognize their mothers at all, either through vision or vocalizations, since during their first weeks after birth, they responded to any gazelle that approached their hiding area. By a month after birth, when mothers and fawns began to stay together for longer periods of time, their recognition process became more enhanced, and in addition to olfactory cues, the mother and her young began to use more and more visual cues for longer distance identification, as well as vocalizations for shorter distances. Similar dynamics are likely typical for most hiding species, although information for wild ungulates is still very limited, especially for those with strong hider behaviors.

Antipredator strategy of female goitered gazelles (Gazella subgutturosa Guld., 1780) with hiding fawn.

In ungulates, predation is often a major cause of infant mortality and likely plays an important role in shaping maternal care strategies that favor progeny survival. The anti-predator strategies of ungulates can be broadly categorized into two groups, hiding infants and following infants. We studied the maternal behavioral strategies of goitered gazelle, which is a typical representative of a hiding species. We found that shortly after birth, goitered gazelle mothers (1) stayed at the greatest distances from their hiding fawns; (2) spent the shortest amount of time together with their fawns, and then only for suckling (during the active phase) which was also the longest inter-suckling intervals (during the hiding phase); (3) kept twins separated in different hiding places and suckled them individually one after the other; (4) changed fawns' hiding places after every active period, travelling with them during the whole suckling bout; (5) oriented their body and muzzle most often toward their hiding young during the fawn's hiding phase; and (6) demonstrated the highest level of vigilance during their approaches to their hiding fawns. The anti-predator strategy of goitered gazelle females was similar to that observed in some North American (Antilocapra americana, Odocoileus hemionus and Odocoileus virginianus) and Eurasian (Dama dama and Capreolus capreolus) ungulate species that also demonstrate hiding behavior. Females of these species live on different continents with disparate environments and different predatory threats, but share anti-predator strategies, which are likely the result of convergent evolution in Bovids and Cervids.

Seasonal dynamics of agonistic displays in territorial and non-territorial males of goitered gazelle.

Aggression serves a great variety of social functions, one of which is protection of individual territories from intruders. Territorial males of many antelope species show aggressive noncontact displays, and only rarely fight. It has been suggested that ungulate males tend to have more frequent and longer aggressive interactions with rivals of similar age or social status than with males of dissimilar status. In the present paper, we test whether territorial and non-territorial males behave in a similar manner and avoid fights, and whether or not they preferentially direct aggressive and longer agonistic interactions towards males of similar age or social status, rather than towards other classes of males. We found that territorial males usually avoided straight fights with peers, and instead mainly used noncontact displays in aggressive interactions. In contrast, non-territorial males used fights considerably more often, especially during the onset of territoriality in April to May, when these males had their most frequent aggressive interactions. Territorial bucks aggressively interacted most frequently with non-territorial males and significantly less often with other territorial males, but agonistic noncontact displays between territorial males lasted the longest. In contrast, non-territorial males addressed their aggressive noncontact displays and fights most often to peers and less frequently to sub-adults. Asymmetry in the social status of territorial vs. non-territorial males was likely responsible for the distinctively different agonistic behaviors shown by the two types of males, which in turn are likely due to the different costs and benefits each male can accrue from these aggressive interactions.

Does social status of males change their aggressive behavior repertoire in goitered gazelle (gazella subgutturosa guld., 1780)?

Aggression in ungulates is a very common behavior which serves a great variety of social functions, the most important of which is territorial protection from intruders. Typically during the rut, territorial males in Antilopinae species have access to mating females, and territoriality leads to a drastic change in the males' lifestyle as they spend most of their aggressive efforts on protecting their territories from other males. In contrast, non-territorial males generally behave in a constant manner all year round, with most of their aggression spent on hierarchical interactions within groups. In this paper, we discuss the differences in aggressive behaviors between territorial and non-territorial males of goitered gazelles (Gazella subgutturosa). We found that territorial males of this species demonstrated most of their aggressive displays, such as threat postures and space-claim patterns, to other territorial males-neighbors, but rarely chased after them at the end of a conflict. Inversely, territorial males frequently chased non-territorial and immature males while only occasionally demonstrating aggressive patterns. Non-territorial males mostly chased other males in their agonistic interactions, displaying threat postures less often than territorial males, but also showing aggressive patterns not found in territorial males. So we concluded that territorial and non-territorial males of goitered gazelles had different repertoires of aggressive behaviors, and when adult males switched their social status from territorial during the rut to non-territorial outside the rut, they obviously changed their preference in aggressive behaviors accordingly.

Roaring function in male goitered gazelles.

Most of the vocalizations of Antilopinae males are soft and usually only heard from a very close distance. The goitered gazelle is a rare exception to this rule, and during the rutting period territorial males of this species are among the noisiest antelopes. Rutting vocalization is such an essential part of the rutting behavior in goitered gazelle that adult males have a hypertrophic larynx, the muscle tissues of which increase considerably in size during the rut. We were interested in the frequency and variance with which male goitered gazelles emit their calls depending on an animal's age, reproductive status and time of the year in order to understand the main function of the rutting vocalizations. We found that roaring was mostly related to courting displays, while vocalizations during aggressive displays were less frequent in male-male interactions. Acoustic signals likely enhance courtship displays and also may aid in accelerating female ovulation, promoting synchronization of breeding cycles during the mating and birthing periods, which last only several days for most of the females in our population. We discuss the potential benefits of such behaviors and compare it to other species living in similarly extreme environments.

Severity score system for progressive myelopathy: development and validation of a new clinical scale

Progressive myelopathies can be secondary to inborn errors of metabolism (IEM) such as mucopolysaccharidosis, mucolipidosis, and adrenomyeloneuropathy. The available scale, Japanese Orthopaedic Association (JOA) score, was validated only for degenerative vertebral diseases. Our objective is to propose and validate a new scale addressing progressive myelopathies and to present validating data for JOA in these diseases. A new scale, Severity Score System for Progressive Myelopathy (SSPROM), covering motor disability, sphincter dysfunction, spasticity, and sensory losses. Inter- and intra-rater reliabilities were measured. External validation was tested by applying JOA, the Expanded Disability Status Scale (EDSS), the Barthel index, and the Osame Motor Disability Score. Thirty-eight patients, 17 with adrenomyeloneuropathy, 3 with mucopolysaccharidosis I, 3 with mucopolysaccharidosis IV, 2 with mucopolysaccharidosis VI, 2 with mucolipidosis, and 11 with human T-cell lymphotropic virus type-1 (HTLV-1)-associated myelopathy participated in the study. The mean ± SD SSPROM and JOA scores were 74.6 ± 11.4 and 12.4 ± 2.3, respectively. Construct validity for SSPROM (JOA: r = 0.84, P < 0.0001; EDSS: r = -0.83, P < 0.0001; Barthel: r = 0.56, P < 0.002; Osame: r = -0.94, P < 0.0001) and reliability (intra-rater: r = 0.83, P < 0.0001; inter-rater: r = 0.94, P < 0.0001) were demonstrated. The metric properties of JOA were similar to those found in SSPROM. Several clinimetric requirements were met for both SSPROM and JOA scales. Since SSPROM has a wider range, it should be useful for follow-up studies on IEM myelopathies.

Severity score system for progressive myelopathy: development and validation of a new clinical scale.

Progressive myelopathies can be secondary to inborn errors of metabolism (IEM) such as mucopolysaccharidosis, mucolipidosis, and adrenomyeloneuropathy. The available scale, Japanese Orthopaedic Association (JOA) score, was validated only for degenerative vertebral diseases. Our objective is to propose and validate a new scale addressing progressive myelopathies and to present validating data for JOA in these diseases. A new scale, Severity Score System for Progressive Myelopathy (SSPROM), covering motor disability, sphincter dysfunction, spasticity, and sensory losses. Inter- and intra-rater reliabilities were measured. External validation was tested by applying JOA, the Expanded Disability Status Scale (EDSS), the Barthel index, and the Osame Motor Disability Score. Thirty-eight patients, 17 with adrenomyeloneuropathy, 3 with mucopolysaccharidosis I, 3 with mucopolysaccharidosis IV, 2 with mucopolysaccharidosis VI, 2 with mucolipidosis, and 11 with human T-cell lymphotropic virus type-1 (HTLV-1)-associated myelopathy participated in the study. The mean ± SD SSPROM and JOA scores were 74.6 ± 11.4 and 12.4 ± 2.3, respectively. Construct validity for SSPROM (JOA: r = 0.84, P < 0.0001; EDSS: r = -0.83, P < 0.0001; Barthel: r = 0.56, P < 0.002; Osame: r = -0.94, P < 0.0001) and reliability (intra-rater: r = 0.83, P < 0.0001; inter-rater: r = 0.94, P < 0.0001) were demonstrated. The metric properties of JOA were similar to those found in SSPROM. Several clinimetric requirements were met for both SSPROM and JOA scales. Since SSPROM has a wider range, it should be useful for follow-up studies on IEM myelopathies.

Resonant soft x-ray scattering from stepped surfaces of SrTiO3.

We studied the resonant diffraction signal from stepped surfaces of SrTiO(3) at the Ti 2p → 3d (L(2,3)) resonance in comparison with x-ray absorption (XAS) and specular reflectivity data. The steps on the surface form an artificial superstructure suitable as a model system for resonant soft x-ray diffraction. A small step density on the surface is sufficient to produce a well defined diffraction peak. We determined the optical parameters of the sample across the resonance and found that the differences between the energy dependence of the x-ray absorption signal, the specular reflectivity and the step-related peak reflect the different quantities probed in these signals. When recorded at low incidence or detection angles, XAS and specular reflectivity spectra are strongly distorted by the changes of the angle of total reflection with energy. The resonant diffraction spectrum is less affected and can be used as a spectroscopic probe even in less favorable geometries.

Flexoelectric rotation of polarization in ferroelectric thin films.

Strain engineering enables modification of the properties of thin films using the stress from the substrates on which they are grown. Strain may be relaxed, however, and this can also modify the properties thanks to the coupling between strain gradient and polarization known as flexoelectricity. Here we have studied the strain distribution inside epitaxial films of the archetypal ferroelectric PbTiO(3), where the mismatch with the substrate is relaxed through the formation of domains (twins). Synchrotron X-ray diffraction and high-resolution scanning transmission electron microscopy reveal an intricate strain distribution, with gradients in both the vertical and, unexpectedly, the horizontal direction. These gradients generate a horizontal flexoelectricity that forces the spontaneous polarization to rotate away from the normal. Polar rotations are a characteristic of compositionally engineered morphotropic phase boundary ferroelectrics with high piezoelectricity; flexoelectricity provides an alternative route for generating such rotations in standard ferroelectrics using purely physical means.

Dielectrophoretic alignment of metal and metal oxide nanowires and nanotubes: a universal set of parameters for bridging prepatterned microelectrodes.

Nanowires and nanotubes were synthesized from metals and metal oxides using templated cathodic electrodeposition. With templated electrodeposition, small structures are electrodeposited using a template that is the inverse of the final desired shape. Dielectrophoresis was used for the alignment of the as-formed nanowires and nanotubes between prepatterned electrodes. For reproducible nanowire alignment, a universal set of dielectrophoresis parameters to align any arbitrary nanowire material was determined. The parameters include peak-to-peak potential and frequency, thickness of the silicon oxide layer, grounding of the silicon substrate, and nature of the solvent medium used. It involves applying a field with a frequency >10(5) Hz, an insulating silicon oxide layer with a thickness of 2.5 µm or more, grounding of the underlying silicon substrate, and the use of a solvent medium with a low dielectric constant. In our experiments, we obtained good results by using a peak-to-peak potential of 2.1 V at a frequency of 1.2 × 10(5) Hz. Furthermore, an indirect alignment technique is proposed that prevents short circuiting of nanowires after contacting both electrodes. After alignment, a considerably lower resistivity was found for ZnO nanowires made by templated electrodeposition (2.2-3.4 × 10(-3) Ωm) compared to ZnO nanorods synthesized by electrodeposition (10 Ωm) or molecular beam epitaxy (MBE) (500 Ωm).

Parallel electron-hole bilayer conductivity from electronic interface reconstruction.

The perovskite SrTiO3-LaAlO3 structure has advanced to a model system to investigate the rich electronic phenomena arising at polar oxide interfaces. Using first principles calculations and transport measurements we demonstrate that an additional SrTiO3 capping layer prevents atomic reconstruction at the LaAlO3 surface and triggers the electronic reconstruction at a significantly lower LaAlO3 film thickness than for the uncapped systems. Combined theoretical and experimental evidence (from magnetotransport and ultraviolet photoelectron spectroscopy) suggests two spatially separated sheets with electron and hole carriers, that are as close as 1 nm.