Showing papers by "Royal Holloway, University of London published in 2003"

Bird Song: Biological Themes and Variations

Abstract: Introduction 1. The study of bird song 2. Production and perception 3. How song develops 4. Getting the message across 5. When do birds sing? 6. Recognition and territorial defence 7. Sexual selection and female choice 8. Themes and variations 9. Variation in time and space List of common and scientific names References Index.

Certificateless Public Key Cryptography

Abstract: This paper introduces and makes concrete the concept of certificateless public key cryptography (CL-PKC), a model for the use of public key cryptography which avoids the inherent escrow of identity-based cryptography and yet which does not require certificates to guarantee the authenticity of public keys The lack of certificates and the presence of an adversary who has access to a master key necessitates the careful development of a new security model We focus on certificateless public key encryption (CL-PKE), showing that a concrete pairing-based CL-PKE scheme is secure provided that an underlying problem closely related to the Bilinear Diffie-Hellman Problem is hard

Certificateless public key cryptography

Abstract: This paper introduces and makes concrete the concept of certificateless public key cryptography (CL-PKC), a model for the use of public key cryptography which avoids the inherent escrow of identity-based cryptography and yet which does not require certificates to guarantee the authenticity of public keys. The lack of certificates and the presence of an adversary who has access to a master key necessitates the careful development of a new security model. We focus on certificateless public key encryption (CL-PKE), showing that a concrete pairing-based CL-PKE scheme is secure provided that an underlying problem closely related to the Bilinear Diffie-Hellman Problem is hard.

Interaction between States and Citizens in the Age of the Internet: “e-Government” in the United States, Britain, and the European Union

Abstract: We examine the origins of the recent shift towards “e-government” in three cases: the United States, Britain, and the European Union. We set out three heuristic models of interaction between states and citizens that might underpin the practice of “e-government.” Focusing on U.S., British, and European Union initiatives, we undertake a comparative analysis of the evolution of key policy statements on e-government reform in national (and supranational) government. We conclude that the democratic potential of the Internet has been marginalized as a result of the ways in which government use of such technology has been framed since the early 1990s. An executive-driven, “managerial” model of interaction has assumed dominance at the expense of “consultative” and “participatory” possibilities.

Not-only-a-title.

Abstract: In the course of eliciting feedback on possible titles for this new journal the comments revealed a fascinating range of views on the terminology commonly used and abused in the literature. We describe here some highlights of the exploration on the meaning and the implication of the words that led to the title chosen after much deliberation. The working title used by the Editor, Marcello Tamburini, during the early planing stages of this journal was 'Quality of Life Outcomes'. When he issued invitations to join the Editorial Board, Clare Bradley replied that there was indeed scope for the kind of journal described and welcomed the initiative but expressed concern about the title as follows: "I think the use of the term 'quality of life' in the title of the journal Quality of Life Research' has contributed to the confusion about the measures described within the journal. Health status measures are often referred to as quality of life measures when they are actually measuring quality of health not quality of life. There are very important differences between the two and when those differences are not recognised it can lead to erroneous conclusions. I attach a commentary that was published last year in The Lancet where I discuss these issues [1]. "I hope you will understand why I would not want to have a journal called 'Quality of Life Outcomes' that then included papers on health status measures, patient satisfaction etc. Having said that, I think that health status and satisfaction measures are important too and I would like to see more outlets for publishing such material. Thus, rather than narrow down the content to fit the title of 'Quality of Life Outcomes', I would prefer to broaden the title to include all such measures. 'Patient Reported Outcomes' is becoming the new well-recognised phrase in this field and this might make a good title for a journal. What do you think?" The Lancet commentary attached gave the example of the UK Prospective Diabetes Study [2] as one of many that has erroneously used a health status measure, in this case the EQ-5D (also known as the EuroQoL), as if it were a measure of quality of life. When no differences were found between EQ-5D scores of participants with Type 2 diabetes who were more intensively treated on insulin and scores of those treated less intensively with oral hypoglycaemic agents or diet alone, the UKPDS researchers concluded that the therapies were neutral in their effect on quality of life [3]. Clare Bradley pointed out that given the nature of the EQ-5D health status measure, in fact what had been shown was that the therapies had no differential effect on perceived health which is a very different matter. Perhaps surprisingly, more intensive treatment didn't make these patients feel any healthier. We don't know what it did to their quality of life because it wasn't measured. The problem of misinterpreting health status measures as if they were measuring quality of life continues and is not restricted to the EQ-5D. Speight has recently critiqued one of the many papers that wrongly describes the SF-36 as a measure of quality of life [4]. Marcello Tamburini circulated Clare Bradley's letter and attachment to 21 Editorial Board members when asking which of four possible titles they preferred and why. The four options offered were: 1. Quality of Life Outcomes 2. Health and Quality of Life Outcomes 3. Health-related Quality of Life Outcomes 4. Patient Reported Outcomes The 16 immediate replies narrowed down the choice to options 2 and 4. A ballot was then taken among 63 experts in the field (most of them editorial board members of the new Journal). They were sent an extract from information presented as background to a symposium (May 19 2002) on Patient-Reported Outcomes to be held by the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) (Table ​(Table1).1). The results of the ballot were as follows: Table 1 Background – PATIENT-REPORTED OUTCOMES 'PRO' SYMPOSIUM CONCEPTUAL AND METHODOLOGICAL ISSUES – International Society for Pharmacoeconomics and Outcomes Research Preferences and Number of Votes • Missing 10 • No preference 2 • Preferred 'Health and Quality of Life Outcomes' 33 • Preferred 'Patient Reported Outcomes' 18 Reasons for preference were requested along with votes and those reasons are interesting (Table ​(Table2).2). It appeared to be accepted that 'patient reported outcomes' would cover the intended subject matter of the journal fairly well. However, there was one notable exception – we may not wish to restrict coverage to the reports of patients but may also wish to publish work that includes reports of family members and carers, and reports of people at risk of health problems who are not currently patients. However, as Deborah Lubeck pointed out 'Some quality of life studies still include instruments that are really physician completed symptom checklists that are not patient reported'. It would be an advantage to have a title that encouraged use of patient reports. Health and Quality of Life Outcomes had its own limitations concerning coverage. It would cover health status, symptoms, and, perhaps, well being under the 'health' label as well as quality of life measures under their own banner, and these could include reports by non-patients as well as by patients. However, it seemed that certain outcomes were excluded, in particular measures of satisfaction, and this was not intended. Patient Reported Outcomes was a broader term in this respect and could include patient satisfaction. Dorothy Keininger suggested that Patient Reported Outcomes might embrace articles on utilisation and economic data and asked if the journal intended to publish such articles (it does) and she was not alone in raising this question. Thus there was concern that Patient Reported Outcomes might be too narrow in excluding non-patient community surveys, carer's reports and chart audits. Table 2 Comments on the title of the new journal It was widely recognised that 'patient reported outcomes' was a new term and would be unfamiliar to many potential readers of this new journal. The novelty was greeted with caution by some and enthusiasm by others. There was concern that the term was 'somewhat obscure' although 'becoming better recognised' and that it was 'too cryptic' while Health and Quality of Life Outcomes was more 'self-explanatory and descriptive'. Dorothy Keininger suggested that patient reported outcomes may not be understood 'outside of the circle of researchers who follow ISPOR and the FDA' (Federal Drugs Administration). In contrast there was some suggestion that 'Maybe Patient Reported Outcomes will become the new buzz word that quality of life was...' (Anne Coscarelli), and that 'Here is a chance to be on the cutting edge of a new way of thinking about outcomes that puts the patient's view first' (Carol Buckhardt). Franco Toscani expressed a clear preference for Patient Reported Outcomes, commenting 'do you remember the term "palliative care"? When we started using it, it looked a strange, unusual, peculiar term, and many colleagues suggested rather "continuing care". History always prizes the new and difficult, not the old and comfortable. If you need work and application for making Patient Reported Outcomes understandable, clear and accepted, well, this is part of the fun!' Catherine Acquadro was equally confident of her preference for Patient Reported Outcomes (PRO) Journal. 'As Clare tells so aptly, PRO has a broader scope, and will include HRQL (Health Related Quality of Life) as well as satisfaction with treatment, health status measures, global impression, well-being etc. Moreover the term PRO is widely accepted by regulators especially by the FDA'. Marcello Tamburini declared himself to be 'lacerate' between the two titles, welcoming the familiarity of Health and Quality of Life and the word 'patient' in Patient Reported Outcomes. He observed that 'patient' occurs in the titles of only 17 of 4,600 biomedical journals included in Medline. A downside of Patient Reported Outcomes is that the term 'patient' has unfortunate and inappropriate connotations of passivity that Clare Bradley would rather avoid although others have restricted their concern to the fact that a focus on patients excludes other groups of interest. The term does, however, have advantages over the old chestnut 'subjective outcomes', the reverse of which was the much-prized 'objective outcomes' (also known as 'hard outcomes') against which 'subjective outcomes' (or 'soft outcomes') came a poor second in the typical medical mind if not the psychological one. Finally, as pointed out by John Ware in his response to the ballot, 'A noteworthy strength of 'Health and Quality of Life Outcomes' is that it recognises the crucial distinction between health and quality of life'. The majority of the Editorial Board members expressed a preference for Health and Quality of Life Outcomes. The outcomes referred to here are more specific than those encompassed by 'patient reported outcomes' and the title does not specify some outcomes that we may go on to include in the journal, such as patient satisfaction. This title has the advantage of familiarity but also makes the crucial distinction between two of the most important goals attainable – health and quality of life.

Deep roots of the Messinian salinity crisis

Abstract: The Messinian salinity crisis—the desiccation of the Mediterranean Sea between 5.96 and 5.33 million years (Myr) ago1—was one of the most dramatic events on Earth during the Cenozoic era2. It resulted from the closure of marine gateways between the Atlantic Ocean and the Mediterranean Sea, the causes of which remain enigmatic. Here we use the age and composition of volcanic rocks to reconstruct the geodynamic evolution of the westernmost Mediterranean from the Middle Miocene epoch to the Pleistocene epoch (about 12.1–0.65 Myr ago). Our data show that a marked shift in the geochemistry of mantle-derived volcanic rocks, reflecting a change from subduction-related to intraplate-type volcanism, occurred between 6.3 and 4.8 Myr ago, largely synchronous with the Messinian salinity crisis. Using a thermomechanical model, we show that westward roll back of subducted Tethys oceanic lithosphere and associated asthenospheric upwelling provides a plausible mechanism for producing the shift in magma chemistry and the necessary uplift (approx1 km) along the African and Iberian continental margins to close the Miocene marine gateways, thereby causing the Messinian salinity crisis.

Mitochondrial remnant organelles of Giardia function in iron-sulphur protein maturation

Abstract: Giardia intestinalis (syn. lamblia) is one of the most widespread intestinal protozoan pathogens worldwide, causing hundreds of thousands of cases of diarrhoea each year. Giardia is a member of the diplomonads, often described as an ancient protist group whose primitive nature is suggested by the lack of typical eukaryotic organelles (for example, mitochondria, peroxisomes), the presence of a poorly developed endomembrane system and by their early branching in a number of gene phylogenies. The discovery of nuclear genes of putative mitochondrial ancestry in Giardia and the recent identification of mitochondrial remnant organelles in amitochondrial protists such as Entamoeba histolytica and Trachipleistophora hominis suggest that the eukaryotic amitochondrial state is not a primitive condition but is rather the result of reductive evolution. Using an in vitro protein reconstitution assay and specific antibodies against IscS and IscU--two mitochondrial marker proteins involved in iron-sulphur cluster biosynthesis--here we demonstrate that Giardia contains mitochondrial remnant organelles (mitosomes) bounded by double membranes that function in iron-sulphur protein maturation. Our results indicate that Giardia is not primitively amitochondrial and that it has retained a functional organelle derived from the original mitochondrial endosymbiont.

'High-performance' Management Practices, Working Hours and Work-Life Balance

Abstract: The effects of selected high-performance practices and working hours on work-life balance are analysed with data from national surveys of British employees in 1992 and 2000. Alongside long hours, which are a constant source of negative job-to-home spillover, certain 'high-performance' practices have become more strongly related to negative spillover during this period. Surprisingly, dual-earner couples are not especially liable to spillover - if anything, less so than single-earner couples. Additionally, the presence of young children has become less important over time. Overall, the results suggest a conflict between high-performance practices and work-life balance policies.

Observation of a Narrow Meson State Decaying to Ds+π0 at a Mass of 2.32 GeV/c2

Abstract: We have observed a narrow state near 2.32 GeV/c(2) in the inclusive D(+)(s)pi(0) invariant mass distribution from e(+)e(-) annihilation data at energies near 10.6 GeV. The observed width is consistent with the experimental resolution. The small intrinsic width and the quantum numbers of the final state indicate that the decay violates isospin conservation. The state has natural spin-parity and the low mass suggests a J(P)=0(+) assignment. The data sample corresponds to an integrated luminosity of 91 fb(-1) recorded by the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) storage ring.

‘High-performance’ Management Practices, Working Hours and Work–Life Balance

Abstract: The effects of selected high-performance practices and working hours on work–life balance are analysed with data from national surveys of British employees in 1992 and 2000. Alongside long hours, which are a constant source of negative job-to-home spillover, certain ‘high-performance’ practices have become more strongly related to negative spillover during this period. Surprisingly, dual-earner couples are not especially liable to spillover — if anything, less so than single-earner couples. Additionally, the presence of young children has become less important over time. Overall, the results suggest a conflict between high-performance practices and work-life balance policies.

Gender, social support, and PTSD in victims of violent crime.

Abstract: Gender differences in social support levels and benefits were investigated in 118 male and 39 female victims of violent crime assessed for PTSD symptomatology 1 and 6 months postcrime. Within 1 month postcrime both genders reported similar levels of positive support and support satisfaction, but women reported significantly more negative responses from family and friends. Women also reported an excess of PTSD symptoms that was similar at 1 and 6 months postcrime, and negative responses mediated the relationship between gender and later symptoms. Overall negative response and support satisfaction, but not positive support, were significantly associated with PTSD symptoms. However, the effects of support satisfaction and negative response on 6-month symptoms were significantly greater for women than men. The findings are consistent with previous studies of predominantly female assault victims concerning the stronger impact of negative over positive support, and might help explain women's higher PTSD risk in civilian samples.

Measles outbreaks in a population with declining vaccine uptake.

Abstract: Measles is a highly infectious and potentially dangerous disease. Before mass vaccination was started in the United Kingdom, measles caused an average of 100 deaths per year ( [1][1] ). Since the introduction of vaccination, vaccine uptake has risen from around 50% in 1968 to 76% in 1988. After the

Public private partnerships: an introduction

Abstract: Public private partnerships (PPPs) are a recent extension of what has now become well known as the “new public management” agenda for changes in the way public services are provided. PPPs involve organisations whose affiliations lie in respectively the public and private sectors working together in partnership to provide public services. This special issue of the Accounting, Auditing & Accountability Journal explores this new development, which, in its most advanced form, is contained in the UK’s Private Finance Initiative (PFI) but is now spreading across the world in multiple forms. This introduction provides an overview of this development as well as an outline of the seven papers that make up this special issue. These seven papers are divided into two parts – the first four looking at different aspects of PFI and the latter three providing three country‐based (from the USA, New Zealand and Australia) studies of PFI/PPP. Many questions about the nature, regulation, pre‐decision analysis and post‐project evaluation are addressed in these papers but many research questions remain unanswered, as this Introduction makes plain.

Song as an honest signal of past developmental stress in the European starling (Sturnus vulgaris)

Abstract: Bird song is a sexually selected male trait where females select males on the basis of song quality. It has recently been suggested that the quality of the adult male song may be determined by nutritional stress during early development. Here, we test the 'nutritional–stress hypothesis' using the complex song of the European starling. Fledgling starlings were kept under experimental treatment (unpredictable short–term food deprivations) or control conditions (ad libitum food supply), for three months immediately after independence. We measured their physiological and immune responses during the treatment and recorded song production during the following spring. Birds in the experimental group showed increased mass during the treatment and also a significantly suppressed humoral response compared with birds in the control group. There was no difference between the groups in the cell–mediated response. Next spring, males in the experimental group spent less time singing, sang fewer song bouts, took longer to start singing and also sang significantly shorter song bouts. These data support the hypothesis that both the quality and quantity of song produced by individual birds reflect past developmental stress. The results also suggest the 'nutritional–stress hypothesis' is best considered as a more general 'developmental–stress hypothesis'.

Routes to remembering: the brains behind superior memory

Abstract: Why do some people have superior memory capabilities? We addressed this age-old question by examining individuals renowned for outstanding memory feats in forums such as the World Memory Championships. Using neuropsychological measures, as well as structural and functional brain imaging, we found that superior memory was not driven by exceptional intellectual ability or structural brain differences. Rather, we found that superior memorizers used a spatial learning strategy, engaging brain regions such as the hippocampus that are critical for memory and for spatial memory in particular. These results illustrate how functional neuroimaging might prove valuable in delineating the neural substrates of mnemonic techniques, which could broaden the scope for memory improvement in the general population and the memory-impaired.

PlantProm: a database of plant promoter sequences

Abstract: PlantProm DB, a plant promoter database, is an annotated, non-redundant collection of proximal promoter sequences for RNA polymerase II with experimentally determined transcription start site(s), TSS, from various plant species. The first release (2002.01) of PlantProm DBcontains 305 entries including 71, 220 and 14 promoters from monocot, dicot and other plants, respectively. It provides DNA sequence of the promoter regions (� 200 : þ51) with TSS on the fixed position þ201, taxonomic/promoter type classification of promoters and Nucleotide Frequency Matrices (NFM) for promoter elements: TATA-box, CCAAT-box and TSS-motif (Inr). Analysis of TSS-motifs revealed that their composition is different in dicots and monocots, as well as for TATA and TATA-less promoters. The database serves as learning set in developing plant promoter prediction programs. One such program (TSSP) based on discriminant analysis has been created by Softberry Inc. and the application of a support vector machine approach for promoter identification is under development. PlantProm DBis available at http://mendel.cs. rhul.ac.uk/ and http://www.softberry.com/.

Interplate dispersal paths for megathermal angiosperms

Abstract: The dispersal of megathermal angiosperms between tectonic plates is reviewed on the basis of fossil evidence for the Cretaceous and Tertiary periods, since the radiation of the angiosperms, and the period of break-up of Gondwana. The combination of tectonic plate disassembly and redistribution, coupled with phases of global warming followed by pronounced cooling, has resulted in the formation of intermittent dispersal opportunities for frost-intolerant plants, and has been a major factor in determining the direction of angiosperm diversification. The Early Cretaceous radiation of angiosperms seems to show little relationship to the formation of Tethys. However, for the Late Cretaceous and Tertiary nine relevant dispersal routes can be differentiated that can be divided into two distinct categories: routes which formed following the break-up of Gondwana during the Late Cretaceous and Earlier Tertiary, when warm climates encouraged dispersal of megathermal elements globally, and routes which formed since the Middle Eocene, following phases of plate collision, as global climates were cooling down, inhibiting such dispersal. Most inter-plate dispersal of megathermal angiosperms took place in the Late Cretaceous and Early Tertiary at a time when global climates were markedly different from those of today, and the global area of megathermal vegetation several times greater than at present. Under such a scenario, it is likely than opportunities for speciation were much higher than for present-day megathermal plants.

The reach-to-grasp movement in children with autism spectrum disorder.

Abstract: Autism is associated with a wide and complex array of neurobehavioural symptoms. Examination of the motor system offers a particularly appealing method for studying autism by providing information about this syndrome that is relatively immune to experimental influence. In this article, we considered the relationship between possible movement disturbance and symptoms of autism and introduced an experimental model that may be useful for rehabilitation and diagnostic purposes: the reach-to-grasp movement. Research is reviewed that characterizes kinematically the reach-to-grasp movement in children with autism compared with age-matched 'controls'. Unlike the age-matched children, autistic children showed differences in movement planning and execution, supporting the view that movement disturbances may play a part in the phenomenon of autism.

Self-esteem in schizophrenia: Relationships between self-evaluation, family attitudes, and symptomatology

Abstract: Participants with schizophrenia (N = 59) were assessed on self-evaluation, symptomatology, and positive and negative affect (expressed emotion) from significant others An interview-based measure of self-evaluation was used and two independent dimensions of self-esteem were derived: negative and positive evaluation of self As predicted, negative self-evaluation was strongly associated with positive symptoms, a more critical attitude from family members was associated with greater negative self-evaluation, and analyses supported a model whereby the impact of criticism on patients' positive symptoms was mediated by its association with negative self-evaluation The interview-based method of self-esteem assessment was found to be superior to the questionnaire because its predictive effects remained after depressed mood was accounted for

Centennial-to-millennial-scale periodicities of Holocene climate and sediment injections off the western Barents shelf, 75°N

Abstract: At the western continental margin of the Barents Sea, 75°N, hemipelagic sediments provide a record of Holocene climate change with a time resolution of 10–70 years. Planktic foraminifera counts reveal a very early Holocene thermal optimum 10.7–7.7 kyr BP, with summer sea surface temperatures (SST) of 8°C and a much enhanced West Spitsbergen Current. There was a short cooling between 8.8 and 8.2 kyr BP. In the middle and late Holocene summer, SST dropped to 2.5°-5.0°C, indicative of reduced Atlantic heat advection, except for two short warmings near 2.2 and 1.6 kyr BP. Distinct quasi-periodic spikes of coarse sediment fraction (with large portions of lithic grains, benthic and planktic foraminifera) record cascades of cold, dense winter water down the continental slope as a result of enhanced seasonal sea ice formation and storminess on the Barents shelf over the entire Holocene. The spikes primarily cluster near recurrence intervals of 400–650 and 1000–1350 years, when traced over the entire Holocene, but follow significant 885–/840– and 505–/605-year periodicities in the early Holocene. These non-stationary periodicities mimic the Greenland-10Be variability, which is a tracer of solar forcing. Further significant Holocene periodicities of 230, (145) and 93 years come close to the deVries and Gleissberg solar cycles.

A taxonomy of single sign-on systems

Abstract: At present, network users have to manage one set of authentication credentials (usually a username/password pair) for every service with which they are registered Single Sign-On (SSO) has been proposed as a solution to the usability, security and management implications of this situation Under SSO, users authenticate themselves only once and are logged into the services they subsequently use without further manual interaction Several architectures for SSO have been developed, each with different properties and underlying infrastructures This paper presents a taxonomy of these approaches and puts some of the SSO schemes, services and products into that context This enables decisions about the design and selection of future approaches to SSO to be made within a more structured context; it also reveals some important differences in the security properties that can be provided by various approaches

Strontium isotopes in the investigation of early glass production: Byzantine and early islamic glass from the Near East

Abstract: Sr-87\Sr-86 ratios have been determined for glasses from four production sites, dated to between the sixth and the 11th centuries, in the Eastern Mediterranean region. On the basis of elemental analyses, the glasses at each location are believed to have been melted from different raw materials. Two glass groups, from Bet Eli'ezer and Bet She'an, in Israel, are believed to have been based upon mixtures of Levantine coastal sands and natron, and have Sr-87\Sr-86 ratios close to 0.7090, plus high elemental strontium, confirming a high concentration of modern marine shell (Sr-87\Sr-86 similar to 0.7092) in the raw materials. The isotopic compositions of these two groups of glasses differ slightly, however, probably reflecting a varying ratio of limestone to shell because the sands that were utilized were from different coastal locations. Natron-based glasses from a workshop at Tel el Ashmunein, Middle Egypt, have Sr-87\Sr-86 values of 0.70794-0.70798, and low elemental strontium, consistent with the use of limestone or limestone-rich sand in the batch. High-magnesia glasses based on plant ash, from Banias, Israel, have Sr-87\Sr-86 values of 0.70772-0.70780, probably reflecting the isotopic composition of the soils that were parental to the plants that were ashed to make the glass. Strontium and its isotopes offer an approach to identifying both the raw materials and the origins of ancient glasses, and are a potentially powerful tool in their interpretation.

Certificateless Public Key Cryptography.

Abstract: This paper introduces the concept of certificateless public key cryptography (CL-PKC). In contrast to traditional public key cryptographic systems, CL-PKC does not require the use of certificates to guarantee the authenticity of public keys. It does rely on the use of a trusted third party (TTP) who is in possession of a master key. In these respects, CL-PKC is similar to identity-based public key cryptography (ID-PKC). On the other hand, CL-PKC does not suffer from the key escrow property that seems to be inherent in ID-PKC. Thus CL-PKC can be seen as a model for the use of public key cryptography that is intermediate between traditional certificated PKC and ID-PKC. We make concrete the concept of CL-PKC by introducing certificateless public key encryption (CL-PKE), signature and key exchange schemes. We also demonstrate how hierarchical CL-PKC can be supported. The schemes are all derived from pairings on elliptic curves. The lack of certificates and the desire to prove the schemes secure in the presence of an adversary who has access to the master key requires the careful development of new security models. For reasons of brevity, the focus in this paper is on the security of CL-PKE. We prove that our CL-PKE scheme is secure in a fully adaptive adversarial model, provided that an underlying problem closely related to the Bilinear Diffie-Hellman Problem is hard.