On-chip generation and dynamic piezo-optomechanical rotation of single photons.

Integrated photonic circuits are key components for photonic quantum technologies and for the implementation of chip-based quantum devices. Future applications demand flexible architectures to overcome common limitations of many current devices, for instance the lack of tuneabilty or built-in quantum light sources. Here, we report on a dynamically reconfigurable integrated photonic circuit comprising integrated quantum dots (QDs), a Mach-Zehnder interferometer (MZI) and surface acoustic wave (SAW) transducers directly fabricated on a monolithic semiconductor platform. We demonstrate on-chip single photon generation by the QD and its sub-nanosecond dynamic on-chip control. Two independently applied SAWs piezo-optomechanically rotate the single photon in the MZI or spectrally modulate the QD emission wavelength. In the MZI, SAWs imprint a time-dependent optical phase and modulate the qubit rotation to the output superposition state. This enables dynamic single photon routing with frequencies exceeding one gigahertz. Finally, the combination of the dynamic single photon control and spectral tuning of the QD realizes wavelength multiplexing of the input photon state and demultiplexing it at the output. Our approach is scalable to multi-component integrated quantum photonic circuits and is compatible with hybrid photonic architectures and other key components for instance photonic resonators or on-chip detectors.

PREDATION OF Brevicoryne brassicae AND Aphis craccivora BY Eriopis connexa DEPENDING ON AVAILABILITY / Depredación de Brevicoryne brassicae y Aphis craccivora por Eriopis connexa, según disponibilidad

ABSTRACT Predator species under field conditions can face different and variable densities of prey species. This work evaluated the functional response of the neotropical lady beetle Eriopis connexa (Coleoptera: Coccinellidae) subjected to different densities of the aphids Brevicoryne brassicae and Aphis craccivora (Hemiptera: Aphididae). Thus, predation rates were analyzed of fourth-instar larvae and one-day old adults of the lady beetle preying upon the aphids at constant densities of 20, 40, 50, 60, and 70 aphids with 15 repetitions per density. The aphids were offered on 5 cm leaf discs of each plant host. The handling times and attack rates were 0.03 h-1 and 0.27 h-1 for larvae and 0.03 h-1 and 0.15 h-1 for adults fed B. brassicae and 0.59 h-1 and 0.35 h-1 for larvae and 0.70 h-1 and 0.95 h-1 for adults fed A. craccivora, respectively. Both larva and adult lady beetles increased predation rate as a function of prey density offered, with an estimated maximum number of prey consumed of 30.3 and 31.6 B. brassicae and 36.3 and 34.6 of A. craccivora by larva and adult lady beetles at the highest prey density, respectively. In conclusion, larvae and adults of E. connexa exhibited a type II functional response.

RESUMEN Las especies de depredadores en condiciones de campo pueden enfrentar densidades diferentes y variables de sus presas. Este trabajo evaluó la respuesta funcional de la mariquita neotropical Eriopis connexa (Coleoptera: Coccinellidae) sometida a diferentes densidades de los pulgones Brevicoryne brassicae y Aphis craccivora (Hemiptera: Aphididae). Se analizaron las tasas de depredación de larvas de cuarto estadio y adultos de un día de vida en las densidades constantes de 20, 40, 50, 60 y 70 pulgones con 15 repeticiones por densidad. Los pulgones se ofrecieron en discos de 5 cm de hojas de la planta huésped. Los tiempos de manejo y las tasas de ataque fueron 0.03 h-1 y 0.27 h-1 para larvas y 0.03 h-1 y 0.15 h-1 para adultos alimentados con B. brassicae y 0.59 h-1 y 0.35 h-1 para larvas y 0.70 h-1 y 0.95 h-1 para adultos alimentados con A. craccivora, respectivamente. Las larvas y las mariquitas adultas aumentaron la tasa de depredación en función de la densidad de presas ofrecidas, con un número máximo estimado de presas consumidas de 30.3 y 31.6 de B. brassicae y 36.3 y 34.6 de A. craccivora para larvas y mariquitas adultas a la mayor densidad de presas, respectivamente. En conclusión, las larvas y los adultos de E. connexa exhibieron una respuesta funcional del tipo II.

Geochemical background concentrations of potentially toxic elements in soils of the Carajás Mineral Province, southeast of the Amazonian Craton.

The objective of this study was to establish background concentrations of potentially toxic elements (PTEs) in soils from the Carajás Mineral Province (CMP), southeastern Amazonian Craton. The PTEs Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V, and Zn were digested in microwaves and quantified by optical emission spectrometry (ICP OES). The variability of physical-chemical and mineralogical attributes contributed to variation in PTE concentrations. High background concentrations of Al, Fe, Cr, Mn, Mo, Ni, Ti, and V and, in particular, the PTE concentrations of Cd, Cu, Cr, Ba, and Co were greater than the prevention values defined by the Brazilian National Council of Environment. Soil quality reference values (QRVs) were greater than those determined for most Brazilian states and soils in the state of Pará. The high background concentrations and QRVs of PTEs show that the region is strongly influenced by the source material, rich in ferruginous deposits and other associated minerals. The results are an important tool for establishing soil quality standards and public policies for environmental protection in regions naturally PTE enriched.

Author Correction: Optical Absorption Exhibits Pseudo-Direct Band Gap of Wurtzite Gallium Phosphide.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Optical Absorption Exhibits Pseudo-Direct Band Gap of Wurtzite Gallium Phosphide.

Definitive evidence for the direct band gap predicted for Wurtzite Gallium Phosphide (WZ GaP) nanowires has remained elusive due to the lack of strong band-to-band luminescence in these materials. In order to circumvent this problem, we successfully obtained large volume WZ GaP structures grown by nanoparticle-crawling assisted Vapor-Liquid-Solid method. With these structures, we were able to observe bound exciton recombination at 2.14 eV with FHWM of approximately 1 meV. In addition, we have measured the optical absorption edges using photoluminescence excitation spectroscopy. Our results show a 10 K band gap at 2.19 eV and indicate a weak oscillator strength for the lowest energy band-to-band absorption edge, which is a characteristic feature of a pseudo-direct band gap semiconductor. Furthermore, the valence band splitting energies are estimated as 110 meV and 30 meV for the three highest bands. Electronic band structure calculations using the HSE06 hybrid density functional agree qualitatively with the valence band splitting energies.

Thermally Tunable Surface Acoustic Wave Cavities.

We experimentally demonstrate the dynamical tuning of the acoustic field in a surface acoustic wave (SAW) cavity defined by a periodic arrangement of metal stripes on LiNbO3 substrate. Applying a dc voltage to the ends of the metal grid results in a temperature rise due to resistive heating that changes the frequency response of the device up to 0.3%, which can be used to control the acoustic transmission through the structure. The timescale of the switching is demonstrated to be of about 200 ms. In addition, we have also performed finite-element simulations of the transmission spectrum of a model system, which exhibits a temperature dependence consistent with the experimental data. The advances shown here enable easy, continuous, dynamical control and could be applied for a variety of substrates.

Isotopic Heft on the B1 l Silent Mode in Ultra-Narrow Gallium Nitride Nanowires.

Wurtzite semiconductor compounds have two silent modes, B1 l and B1 h. A silent mode is a vibrational mode that carries neither a dipole moment nor Raman polarizability. Thus, they are forbidden in both infrared reflectivity and Raman spectroscopy. Astonishingly, we detected the B1 l mode in high-quality, ultra-narrow GaN nanowires using resonant Raman scattering, although the B1 h was not observed, and there is no immediate explanation for this asymmetric finding. The Raman experiments were performed using several laser lines from 647 to 325 nm; the latter is a wavelength in which Raman becomes resonant. Actually, we observed the B1 l mode only in resonance, indicating that the appearance of this mode is related to Fröhlich electron-phonon interactions; i.e., a dipole moment emerging in the B1 l silent mode may not be present in the B1 h mode. To shed light onto the physical origin of these observations, we performed density functional theory calculations of the lattice dynamics in GaN. We performed a careful analysis of the different physical mechanisms that allow the forbidden mode to appear to explain the physics underlying the nonzero dipole moment in the B1 l mode, and the reason why this dipole moment is not present in the B1 h mode.

The fingerprint of Te-rich and stoichiometric Bi2Te3 nanowires by Raman spectroscopy.

We unambiguously show that the signature of Te-rich bismuth telluride is the appearance of three new peaks in the Raman spectra of Bi2Te3, located at 88, 117 and 137 cm(-1). For this purpose, we have grown stoichiometric Bi2Te3 nanowires as well as Te-rich nanowires. The absence of these peaks in stoichiometric nanowires, even in those with the smallest diameter, shows that they are not related to confinement effects or the lack of inversion symmetry, as stated in the literature, but to the existence of Te clusters. These Te clusters have been found in non-stoichiometric samples by high resolution electron microscopy, while they are absent in stoichiometric samples. The Raman spectra of the latter corresponds to the one for bulk Bi2Te3. The intensity of these Raman peaks are clearly correlated to the Te content. In order to ensure statistically meaningful results, we have investigated several regions from every sample.

Cytotoxic, hematologic and histologic effects of niobium pentoxide in Swiss mice.

The use of metal devices in medical application is increasing but it remains incompletely understood the physiological effects of component degradation. Niobium (Nb) alloys have already been investigated in the 1980's and recent studies demonstrated the potential of Nb as an implant material. The purpose of this study was to determine cytotoxic, hematologic and histologic effects of niobium in Swiss mice. Animals were treated with a single dose of 3 % niobium oxide (Nb2O5) diluted in PBS, i.p. Cytotoxic assay, hematologic and histologic evaluation were done 3, 7 and 12 days after niobium treatment. Data have shown increased number of cells after niobium treatment, but there was no difference in cell viability. Furthermore, it was not observed hematological modification 3, 7 or 12 days after niobium treatment. Despite the fact that animals treated with niobium for 3 and 7 days showed mild degeneration in hepatocytes, mice kept alive for 12 days showed liver cells regeneration. Our results suggested that niobium cytotoxicity was not progressive because 12 days after treatment there was an evident liver regeneration. Data obtained indicated that niobium may be promising alternatives to biomedical applications.

Polarized recombination of acoustically transported carriers in GaAs nanowires.

: The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited electrons and holes in GaAs nanowires deposited on a SAW delay line on a LiNbO3 crystal. The carriers generated in the nanowire by a focused light spot are acoustically transferred to a second location where they recombine. We show that the recombination of the transported carriers occurs in a zinc blende section on top of the predominant wurtzite nanowire. This allows contactless control of the linear polarized emission by SAWs which is governed by the crystal structure. Additional polarization-resolved photoluminescence measurements were performed to investigate spin conservation during transport.

WITHDRAWN: Antidepressants for cocaine dependence.

BACKGROUND: The past decade has witnessed a sustained search for an effective pharmacotherapeutic agent for the treatment of cocaine dependence. While administration of cocaine acutely increases intercellular dopamine, serotonin, and norepinephrine levels by blocking their presynaptic reuptake, chronic cocaine abuse leads to down-regulation of monoamine systems. Post-cocaine use depression and cocaine craving may be linked to this down-regulation. Antidepressant pharmacotherapy, by augmenting monoamine levels, may alleviate cocaine abstinence symptomatology, as well as relieving dysphoria and associated craving by general antidepressant action. OBJECTIVES: To evaluate the efficacy and the acceptability of antidepressants for cocaine dependence SEARCH STRATEGY: We searched Cochrane Drug and Alcohol Group Specialised Register (July 2007), MEDLINE (1966 to July 2007), CINAHL (1982 to July 2007), SCOPUS (July 2007); reference searching; personal communication; conference abstracts; unpublished trials, ongoing trials, relevant web-sites. SELECTION CRITERIA: All randomised controlled trials and controlled clinical trials which focus on the use of any antidepressants for cocaine dependence DATA COLLECTION AND ANALYSIS: The authors independently evaluated the papers, extracted data, rated methodological quality. Doubts were solved throug discussion between all the authors. MAIN RESULTS: 18 studies were included in the review (1177 participants). Positive urine sample for cocaine metabolites was the main efficacy outcome, with no significant results obtained regardless of the type of antidepressant. Compared to other drugs, desipramine performed better but showing just a non significant trend with heterogeneity present as revealed by the chi-square test (8.6, df=3; p=0.04). One single trial showed imipramine performed better than placebo in terms of clinical response according to patient's self-report. A similar rate of patients remaining in treatment was found for both patients taking desipramine or placebo. Results from one single trial suggest fluoxetine patients on SSRIs are less likely to dropout. Similar results were obtained for trials where patients had additional diagnosis of opioid dependence and/or were in methadone maintenance treatment. AUTHORS' CONCLUSIONS: There is no current evidence supporting the clinical use of antidepressants in the treatment of cocaine dependence. Given the high rate of dropouts in this population, clinicians may consider adding psychotherapeutic supportive measures aiming to keep patients in treatment.

WITHDRAWN: Dopamine agonists for cocaine dependence.

BACKGROUND: Cocaine dependence is a common and serious condition, which has become a substantial public health problem. There is a wide and well documented range of consequences associated to chronic use of cocaine, such as medical, psychological and social problems.. Therapeutic management of the cocaine addicts includes an initial period of abstinence from the drug. During this phase the subjects may experience, besides the intense craving for cocaine, symptoms such as depression, fatigue, irritability, anorexia, and sleep disturbances. It was demonstrated that the acute use of cocaine may enhance dopamine transmission and chronically it decreases dopamine concentrations in the brain. Pharmacological treatment that affects dopamine could theoretically reduce these symptoms and contribute to a more successful therapeutic approach. OBJECTIVES: To evaluate the efficacy and acceptability of dopamine agonists for treating cocaine dependence. SEARCH STRATEGY: Electronic searches of Cochrane Library, EMBASE, MEDLINE, PsycLIT, Biological Abstracts and LILACS; reference searching; personal communication; conference abstracts; unpublished trials from pharmaceutical industry; book chapters on treatment of cocaine dependence, was performed for the primary version of this review in 2001. Another search of the electronic databases was done in December of 2002 for this update. The specialised register of trials of the Cochrane Group on Drugs and Alcohol was searched until February 2003. SELECTION CRITERIA: The inclusion criteria for all randomised controlled trials were that they should focus on the use of dopamine agonists on the treatment of cocaine dependence. DATA COLLECTION AND ANALYSIS: The reviewers extracted the data independently and Relative Risks, weighted mean difference and number needed to treat were estimated. The reviewers assumed that people who died or dropped out had no improvement and tested the sensitivity of the final results to this assumption. MAIN RESULTS: Seventeen studies were included, with 1224 participants randomised. Amantadine, bromocriptine, and pergolide were the drugs evaluated. The main outcomes evaluated were positive urine sample for cocaine metabolites, for efficacy, and retention in treatment, as an acceptability measure. There were no significant differences between interventions, and in trials where participants had primary cocaine dependence or had additional diagnosis of opioid dependence and/or were in methadone maintenance treatment. AUTHORS' CONCLUSIONS: Current evidence does not support the clinical use of dopamine agonists in the treatment of cocaine dependence. Given the high rate of dropouts in this population, clinicians may consider adding other supportive measures aiming to keep patients in treatment.

When worlds collide.

ABSTThe UK has a strong tradition of innovative evaluative health care research. There are, however, considerable forces impeding collaboration between clinicians, academics, patients and their advocates and industry. This paper argues that, if the UK is to regain a position at the forefront of clinical research into evaluation of care, some of these forces need to be overcome. Now, with explicit encouragement from funders within the UK's NHS, it is urgent that all parties discover better ways of working together so that more broad and meaningful research can be produced in a timely fashion.

The surgical management of the sentinel lymph node in cutaneous melanoma might be different when the primary lesion was previously resected with 1 cm margin.

AIM: To simulate the effects of previous wide cutaneous melanoma excision in sentinel lymph node (SLN) biopsy feasibility through a change in the radiotracer injection site. MATERIALS AND METHODS: Thirty-three patients with cutaneous melanoma underwent two preoperatory lymphoscintigraphic studies. In the first, the radiopharmaceutical was injected intradermally 0.3 cm away from the lesion/scar. Dynamic images were acquired to find the SLN. On the following day, the procedure was repeated with the radiopharmaceutical injected 1 cm farther from the previous injection sites. The number of lymph nodes and sites of drainage were compared with the findings of the first study. All the patients underwent SLN biopsy using a gamma probe and patent blue. RESULTS: Seventy-five SLNs were identified with radiopharmaceutical injected at 0.3 cm from the lesion versus 82 SLNs when injected at 1.3 cm. All lymph nodes visualized with close injection were identified with the farther injection. Twenty-seven (81%) patients presented the same number and location of SLNs. Six (19%) patients presented more SLNs with the expanded technique, three patients in the same basin and three in a new lymph node station. All metastatic SLNs were harvested by the two injection techniques. CONCLUSION: The value of the SLN biopsy in patients with cutaneous melanoma is maintained even after the primary lesion has been removed with a margin of up to 1 cm. Some patients might show an increased number of SLNs and some might show drainage to additional lymph node stations.

WITHDRAWN: Carbamazepine for cocaine dependence.

BACKGROUND: Cocaine dependence has become a public health problem, developing a significant number of medical, psychological and social problems. Although there is no consensus regarding how to treat cocaine dependence, effective pharmacotherapy has a potentially major role to play as part of a broader treatment milieu. The anti-convulsant carbamazepine, a tricyclic medication that is widely used to treat a variety of neurological and psychiatric disorders, has been used for treatment of cocaine dependence, although its effectiveness has not been established. OBJECTIVES: To determine whether carbamazepine is effective for the treatment of cocaine dependence. SEARCH STRATEGY: We searched: Cochrane Controlled Trials Register (Cochrane Library issue 1, 1999), MEDLINE (f1966 - October 1997), EMBASE (1980 - October 1997), PsycLIT (1974 - July 1997), Biological Abstracts and LILACS (1982 - 1997); scan of reference list of relevant articles; personal communication; conference abstracts; unpublished trials from pharmaceutical industry; book chapters on treatment of cocaine dependence. The specialised register of trials of Cochrane Group on Drugs and Alcohol until February 2003. SELECTION CRITERIA: All randomised controlled trials focused on the use of carbamazepine versus placebo on the treatment of cocaine dependence. Trials including patients with additional diagnosis such as opiate dependence were also eligible. DATA COLLECTION AND ANALYSIS: The reviewers extracted the data independently, Odds Ratios, weighted mean difference and number needed to treat were estimated. Qualitative assessments of the methodology of eligible studies were carried out using validated checklists. The reviewers assumed that people who died or dropped out had no improvement and tested the sensitivity of the final results to this assumption. Where possible analysis was carried out according to the "intention to treat" principles. MAIN RESULTS: 5 studies were included (455 participants). No differences regarding positive urine sample for cocaine metabolites. Scores on Spielberg State Anxiety Inventory slightly favoured carbamazepine, but not statistical significance. Dropouts were high in both groups, less dropout occurred in the carbamazepine group (RR 0.87 95%CI 0.71-1.06). When no retention in treatment was due to side effects no differences were found. The number of participants presenting at least one side effect, was higher in the carbamazepine group (RR 4.33 95% CI 1.45-12.91). AUTHORS' CONCLUSIONS: There is no current evidence supporting the clinical use of Carbamazepine in the treatment of cocaine dependence. Larger randomised investigation must be considered taking into account that these time-consuming efforts should be reserved for medications showing more relevant and promising evidence.

Comparison of carbamazepine and lithium in treatment of bipolar disorder: a systematic review of randomized controlled trials.

OBJECTIVES: To review data from randomized controlled trials (RCTs) assessing the comparative efficacy of carbamazepine and lithium in treatment of acute manic and maintenance phase of bipolar disorder (BD). DESIGN: RCTs were identified through a search strategy that included: electronic databases, reference cross-checking, hand search of non-indexed publications, and book chapters on the treatment of BD comparing carbamazepine with lithium. Outcomes investigated were antimanic effect, trial withdrawal, relapse, hospitalization, need for rescue medication, and presence of adverse effects. Selection of studies and data analysis were performed independently by authors. Whenever possible, data from trials were combined through meta-analyses. Relative risks (RR) were estimated for dichotomous data. RESULTS: In acute mania, carbamazepine was similar to lithium on the following outcomes: trial withdrawal due to adverse effects, number of participants with at least one adverse effect, improvement in the Clinical Global Impression (CGI). In acute mania, carbamazepine was associated with fewer trial withdrawals. In maintenance treatment, carbamazepine was similar to lithium in relapses and hospitalization, but there were fewer trial withdrawals due to adverse effects on lithium. CONCLUSION: This review suggests that carbamazepine might be comparable to lithium in terms of efficacy and safety, and therefore a valuable option in the treatment of both manic and maintenance phases.

Reviewing CATIE for clinicians: balancing benefit and risk using evidence-based medicine tools.

BACKGROUND: In order to learn from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) schizophrenia study and apply its results to day-to-day clinical practice, it would be useful to quantify the benefits and risks of the studied antipsychotics. SCOPE: Reviewing the CATIE results from the perspective of evidence-based medicine metrics of attributable risk (AR), number needed to treat (NNT), number needed to harm (NNH), and likelihood of being helped or harmed (LHH) helps clinicians translate the CATIE findings for individualized treatment in clinical practice. FINDINGS: Use of these evidence-based tools demonstrates that the NNT to avoid a psychiatric hospitalization due to the exacerbation of schizophrenia ranged from 3 to 7 in favor of olanzapine compared with the other antipsychotics. The NNH to produce one treatment-emergent adverse event of weight gain > 7% ranged from -5 to -8 (favoring comparators over olanzapine). Further, when assessing LHH - the likelihood of being helped (avoid a psychiatric hospital admission) compared to the likelihood of being harmed (experience weight gain > 7%) - treatment with olanzapine was consistently associated with greater expectation of benefit than harm (LHH > 1). CONCLUSION: The use of NNT, NNH, and LHH can be helpful in balancing risk versus benefit in selecting antipsychotic treatment. LIMITATIONS: NNT and NNH may vary with baseline risk, and cannot be calculated from continuous variables. LHH may be influenced by an individual's perception of the value of the outcomes compared.