High Speed Visible Light Communication Using Blue GaN Laser Diodes

GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications

AlGaInN laser diode technology for free-space and plastic optical fibre telecom applications

Gallium Nitride laser diodes fabricated from the AlGaInN material system is an emerging technology for laser sources from the UV to visible and is a potential key enabler for new system applications such as free-space (underwater & air bourne links) and plastic optical fibre telecommunications. We measure visible light (free-space and underwater) communications at high frequency (up to 2.5 Gbit/s) and in plastic optical fibre (POF) using a directly modulated GaN laser diode

LSD but not lisuride disrupts prepulse inhibition in rats by activating the 5-HT2A receptor

Compounds that activate the 5-HT2A receptor, such as lysergic acid diethylamide (LSD), act as hallucinogens in humans. One notable exception is the LSD congener lisuride, which does not have hallucinogenic effects in humans even though it is a potent 5-HT2A agonist. LSD and other hallucinogens have been shown to disrupt prepulse inhibition (PPI), an operational measure of sensorimotor gating, by activating 5-HT2A receptors in rats. We tested whether lisuride disrupts PPI in male Sprague–Dawley rats. Experiments were also conducted to identify the mechanism(s) responsible for the effect of lisuride on PPI and to compare the effects of lisuride to those of LSD. Confirming a previous report, LSD (0.05, 0.1, and 0.2 mg/kg, s.c.) reduced PPI, and the effect of LSD was blocked by pretreatment with the selective 5-HT2A antagonist MDL 11,939. Administration of lisuride (0.0375, 0.075, and 0.15 mg/kg, s.c.) also reduced PPI. However, the PPI disruption induced by lisuride (0.075 mg/kg) was not blocked by pretreatment with MDL 11,939 or the selective 5-HT1A antagonist WAY-100635 but was prevented by pretreatment with the selective dopamine D2/D3 receptor antagonist raclopride (0.1 mg/kg, s.c). The effect of LSD on PPI is mediated by the 5-HT2A receptor, whereas activation of the 5-HT2A receptor does not appear to contribute to the effect of lisuride on PPI. These findings demonstrate that lisuride and LSD disrupt PPI via distinct receptor mechanisms and provide additional support for the classification of lisuride as a non-hallucinogenic 5-HT2A agonist

Pervasive and opposing effects of Unpredictable Chronic Mild Stress (UCMS) on hippocampal gene expression in BALB/cJ and C57BL/6J mouse strains

Background: BALB/cJ is a strain susceptible to stress and extremely susceptible to a defective hedonic impact in response to chronic stressors. The strain offers much promise as an animal model for the study of stress related disorders. We present a comparative hippocampal gene expression study on the effects of unpredictable chronic mild stress on BALB/cJ and C57BL/6J mice. Affymetrix MOE 430 was used to measure hippocampal gene expression from 16 animals of two different strains (BALB/cJ and C57BL/6J) of both sexes and subjected to either unpredictable chronic mild stress (UCMS) or no stress. Differences were statistically evaluated through supervised and unsupervised linear modelling and using Weighted Gene Coexpression Network Analysis (WGCNA). In order to gain further understanding into mechanisms related to stress response, we cross-validated our results with a parallel study from the GENDEP project using WGCNA in a meta-analysis design. Results: The effects of UCMS are visible through Principal Component Analysis which highlights the stress sensitivity of the BALB/cJ strain. A number of genes and gene networks related to stress response were uncovered including the Creb1 gene. WGCNA and pathway analysis revealed a gene network centered on Nfkb1. Results from the meta-analysis revealed a highly significant gene pathway centred on the Ubiquitin C (Ubc) gene. All pathways uncovered are associated with inflammation and immune response. Conclusions: The study investigated the molecular mechanisms underlying the response to adverse environment in an animal model using a GxE design. Stress-related differences were visible at the genomic level through PCA analysis highlighting the high sensitivity of BALB/cJ animals to environmental stressors. Several candidate genes and gene networks reported are associated with inflammation and neurogenesis and could serve to inform candidate gene selection in human studies and provide additional insight into the pathology of Major Depressive Disorder

Efficacy and safety of aripiprazole in the treatment of bipolar disorder: a systematic review

Abstract BACKGROUND: The current article is a systematic review concerning the efficacy and safety of aripiprazole in the treatment of bipolar disorder. METHODS: A systematic Medline and repositories search concerning the usefulness of aripiprazole in bipolar disorder was performed, with the combination of the words 'aripiprazole' and 'bipolar'. RESULTS: The search returned 184 articles and was last updated on 15 April 2009. An additional search included repositories of clinical trials and previous systematic reviews specifically in order to trace unpublished trials. There were seven placebo-controlled randomised controlled trials (RCTs), six with comparator studies and one with add-on studies. They assessed the usefulness of aripiprazole in acute mania, acute bipolar depression and during the maintenance phase in comparison to placebo, lithium or haloperidol. CONCLUSION: Aripiprazole appears effective for the treatment and prophylaxis against mania. The data on bipolar depression are so far negative, however there is a need for further study at lower dosages. The most frequent adverse effects are extrapyramidal signs and symptoms, especially akathisia, without any significant weight gain, hyperprolactinaemia or laboratory test changes

Princípios éticos na experimentação animal

The treatment of animals used in research or in education tests requires proper care, scientific judgment and qualified professionals to understand the needs of the animals and the special requirements of the research, tests, and educational programs. The established guidelines aim the development of knowledge necessary for the improvement of health and wellbeing of humans as well as animals to get precise and accurate results. The techniques should not be performed with inappropriate procedures that cause pain or suffering. Some principles should be considered to have an appropriate animal care and treatment

Princípios éticos na experimentação animal

The treatment of animals used in research or in education tests requires proper care, scientific judgment and qualified professionals to understand the needs of the animals and the special requirements of the research, tests, and educational programs. The established guidelines aim the development of knowledge necessary for the improvement of health and wellbeing of humans as well as animals to get precise and accurate results. The techniques should not be performed with inappropriate procedures that cause pain or suffering. Some principles should be considered to have an appropriate animal care and treatment