Quantum Cryptography with Imperfect Apparatus

Quantum key distribution, first proposed by Bennett and Brassard, provides a possible key distribution scheme whose security depends only on the quantum laws of physics. So far the protocol has been proved secure even under channel noise and detector faults of the receiver, but is vulnerable if the photon source used is imperfect. In this paper we propose and give a concrete design for a new concept, {\it self-checking source}, which requires the manufacturer of the photon source to provide certain tests; these tests are designed such that, if passed, the source is guaranteed to be adequate for the security of the quantum key distribution protocol, even though the testing devices may not be built to the original specification. The main mathematical result is a structural theorem which states that, for any state in a Hilbert space, if certain EPR-type equations are satisfied, the state must be essentially the orthogonal sum of EPR pairs.Comment: 7 pages (To appear in FOCS 98

Supporting women who develop poor postnatal mental health: what support do fathers receive to support their partner and their own mental health?

Background: Research regarding support provided for poor maternal postnatal mental health (such as depression, anxiety disorders, and postpartum psychosis) is relatively common. Fathers appear to play an important role supporting partners but many feel alienated within maternity services. Research focusing on fathers is less common. Methods: The current qualitative study aimed to investigate fathers’ experience of support provided to fathers, to help support their partner should she experience poor postnatal mental health. Results: Twenty-five fathers participated in an online questionnaire regarding their experience of their partner’s poor postnatal mental health and the support provided to fathers to help her. Thematic analysis revealed three main themes and seven sub-themes. The themes were: ‘Support received to help support their partner’, ‘Support fathers wanted that was not received’ and ‘Father’s mental health’. The results highlight an overall lack of support for many fathers, despite many wanting support on how to help their partner, information on their own mental health and the services available. Fathers specifically wanted healthcare professionals to sign-post them to someone they can talk to for emotional support, and to be taught coping strategies which would help them to support both their partner and baby. Conclusions: The findings from this study suggest that health professionals and perinatal mental health services need a better understanding about what resources fathers need to support the mental health of themselves and their partner

An energy and resource efficient alkaline flocculation and sedimentation process for harvesting of Chromochloris zofingiensis biomass

Harvesting microalgal cultures is often energetically intensive and costly. To improve efficiencies, a two-step harvesting method utilising alkaline flocculation and sedimentation to pre-concentrate cultures can be used prior to centrifugation. When applied to the microalga Chromochloris zofingiensis, high rates of sedimentation (>90%) were found at low concentrations of base (<10 mM), with the addition of magnesium to the media (via NaOH/MgSO4 or Ca(OH)2/Mg(OH)2) to form Mg(OH)2. The process was scaled to 180 L, where sedimentation was as efficient as that achieved at bench scale. Characterisation of the harvested biomass showed comparable composition (following neutralisation of pH) to biomass recovered solely by centrifugation. The alternative two-step processes were assessed for environmental impacts and cost, which indicated that a two-step harvesting generally performs better than centrifugation alone, but that the locally available electricity source is a critical parameter for optimal solution

Understanding the Barriers Fathers Face to Seeking Help for Paternal Perinatal Depression: Comparing Fathers to Men Outside the Perinatal Period

Research has shown that men are less likely than women to seek help for depression at any time of life due to barriers, including stereotypical masculine norms and stigma. The evidence suggests that approximately 10% of fathers experience postnatal depression, yet new and expectant fathers are not routinely offered screening or support in the same way as mothers. Therefore, this research explored the barriers fathers face to seeking help for paternal perinatal depression (PPD). Data were collected using an online survey. Initially, fathers with postnatal depression were compared to men experiencing depression at another time of their life in terms of their attitudes to seeking psychological help, conformity to masculine norms, self-stigma, and awareness of services. Secondly, a proposed model of help-seeking amongst fathers with postnatal depression was evaluated. Finally, additional barriers to help-seeking for paternal postnatal depression were explored qualitatively. A total of 125 participants took part in the quantitative comparison, and 50 of the fathers also provided qualitative data. No between-group differences were found, suggesting that the existing literature on barriers to seeking help for male depression is applicable to fathers with postnatal depression. The qualitative results also highlighted the need for better awareness of paternal postnatal depression and better access to services for fathers. Limitations, implications for policy, and directions for future research are discussed

Genome-Scale Model Reveals Metabolic Basis of Biomass Partitioning in a Model Diatom

Diatoms are eukaryotic microalgae that contain genes from various sources, including bacteria and the secondary endosymbiotic host. Due to this unique combination of genes, diatoms are taxonomically and functionally distinct from other algae and vascular plants and confer novel metabolic capabilities. Based on the genome annotation, we performed a genome-scale metabolic network reconstruction for the marine diatom Phaeodactylum tricornutum. Due to their endosymbiotic origin, diatoms possess a complex chloroplast structure which complicates the prediction of subcellular protein localization. Based on previous work we implemented a pipeline that exploits a series of bioinformatics tools to predict protein localization. The manually curated reconstructed metabolic network iLB1027_lipid accounts for 1,027 genes associated with 4,456 reactions and 2,172 metabolites distributed across six compartments. To constrain the genome-scale model, we determined the organism specific biomass composition in terms of lipids, carbohydrates, and proteins using Fourier transform infrared spectrometry. Our simulations indicate the presence of a yet unknown glutamine-ornithine shunt that could be used to transfer reducing equivalents generated by photosynthesis to the mitochondria. The model reflects the known biochemical composition of P. tricornutum in defined culture conditions and enables metabolic engineering strategies to improve the use of P. tricornutum for biotechnological applications

Modification of the wettability characteristics of polymethyl methacrylate (PMMA) by means of CO2, Nd:YAG, excimer and high power diode laser radiation

The surface of the bio-material polymethyl methacrylate (PMMA) was treated with CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation. The laser radiation was found to effect varying degrees of change to the wettability characteristics of the material depending upon the laser used. It was observed that interaction with CO2, Nd:YAG and HPDL effected very little change to wettability characteristics of the PMMA. In contrast, interaction of the PMMA with excimer laser radiation resulted an increase in a marked improvement in the wettability characteristics. After excimer laser treatment the surface O2 content was found to have increased and the material was seen to be more polar in nature. The work has shown that the wettability characteristics of the PMMA could be controlled and/or modified with laser surface treatment. However, a wavelength dependence of the change of the wetting properties could not be deduced from the findings of this work

Reductive glutamine metabolism is a function of the α-ketoglutarate to citrate ratio in cells

Reductively metabolized glutamine is a major cellular carbon source for fatty acid synthesis during hypoxia or when mitochondrial respiration is impaired. Yet, a mechanistic understanding of what determines reductive metabolism is missing. Here we identify several cellular conditions where the α-ketoglutarate/citrate ratio is changed due to an altered acetyl-CoA to citrate conversion, and demonstrate that reductive glutamine metabolism is initiated in response to perturbations that result in an increase in the α-ketoglutarate/citrate ratio. Thus, targeting reductive glutamine conversion for a therapeutic benefit might require distinct modulations of metabolite concentrations rather than targeting the upstream signalling, which only indirectly affects the process.German Science Foundation (Grant FE1185)National Institutes of Health (U.S.) (Ruth L. Kirschstein National Research Service Award Postdoctoral Fellowship F32 CA132358)National Institutes of Health (U.S.) (Grant 5-P30-CA14051-39)Damon Runyon Cancer Research FoundationBurroughs Wellcome FundSmith Family FoundationNational Institutes of Health (U.S.) (Grant 1R01CA160458-01A1

The XMM Cluster Survey: Evidence for energy injection at high redshift from evolution of the X-ray luminosity-temperature relation

We measure the evolution of the X-ray luminosity-temperature (L_X-T) relation since z~1.5 using a sample of 211 serendipitously detected galaxy clusters with spectroscopic redshifts drawn from the XMM Cluster Survey first data release (XCS-DR1). This is the first study spanning this redshift range using a single, large, homogeneous cluster sample. Using an orthogonal regression technique, we find no evidence for evolution in the slope or intrinsic scatter of the relation since z~1.5, finding both to be consistent with previous measurements at z~0.1. However, the normalisation is seen to evolve negatively with respect to the self-similar expectation: we find E(z)^{-1} L_X = 10^{44.67 +/- 0.09} (T/5)^{3.04 +/- 0.16} (1+z)^{-1.5 +/- 0.5}, which is within 2 sigma of the zero evolution case. We see milder, but still negative, evolution with respect to self-similar when using a bisector regression technique. We compare our results to numerical simulations, where we fit simulated cluster samples using the same methods used on the XCS data. Our data favour models in which the majority of the excess entropy required to explain the slope of the L_X-T relation is injected at high redshift. Simulations in which AGN feedback is implemented using prescriptions from current semi-analytic galaxy formation models predict positive evolution of the normalisation, and differ from our data at more than 5 sigma. This suggests that more efficient feedback at high redshift may be needed in these models.Comment: Accepted for publication in MNRAS; 12 pages, 6 figures; added references to match published versio