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This work is a review on existing authenticated key exchange (AKE) security models and protocols mainly based on Diffie-Hellman Key Exchange (DHKE). We provide a discussion on the various security models of AKEs, such as the Bellare Rogaway (BR) model, Canetti Krawczyk (CK) model and their variants. Then we provide a review covering over ninety protocols in chronological order. The security models' security features and protocol examples that fit in those security models are exhibited. [ABSTRACT FROM AUTHOR]

In 2015, Chin et al. proposed an extension to the Schnorr IBI scheme using two secret keys to tighten the security based on the discrete logarithmic assumption, namely the Twin-Schnorr IBI. Twin-Schnorr IBI works without pairing operation and this helps to increase the efficiency of the scheme as well as strengthening it's security. In this paper, we extend Chin et al.'s scheme to accommodate hierarchies, namely the Hierarchical Identity-based identification (HIBI). Our scheme uses no pairings and is able to operate faster than pairing based HIBIs. [ABSTRACT FROM AUTHOR]

Objective To describe how various antimicrobials are used in commercial pig herds in Australia and for what disease conditions. Procedure Managers of large pig herds (> 200 sows) across Australia and their veterinarians participated in an internet-based survey in 2006. Questions were asked about herd management, the occurrence of bacterial diseases and the type and frequency of antimicrobial use. An antimicrobial usage index for each herd was derived as a summary of the risk of selection for antimicrobial resistance. Relationships between responses were explored with univariate and multivariate analysis. Results Responses were received for 197 herds estimated to represent at least 51% of all large pig herds in Australia. Most piggeries relied on drugs of low importance in human medicine (e.g. tetracyclines, penicillins and sulfonamides). For the two drugs of high importance in human medicine that can be legally prescribed to pigs in Australia, ceftiofur use was reported in 25% of herds and virginiamycin in none. Infections attributed to Lawsonia, Mycoplasma and Escherichia coli motivated the most use of antimicrobials. No useful association was found between management factors and the antimicrobial use index. Conclusion Most antimicrobial use in the Australian pig industry is based on drugs of low importance to public health. Enhanced control of E. coli infections without reliance on antimicrobials would further reduce the risk of selecting for antimicrobial resistance relevant to public health. The amount of variation in the usage index between herds suggests that antimicrobial use should be constantly reviewed on a herd by herd basis. [ABSTRACT FROM AUTHOR]

Setting up a common secret key for communications between two parties over insecure mobile communication networks is important for many network applications. Previously, Wu and Lin proposed a non-interactive authenticated key agreement over mobile communication networks with security proofs assuming the Bilinear Diffie-Hellman problem is hard. Wu and Lin scheme is unique as the users do not need to interact at all in sharing a secret key. Besides, their scheme will at least achieve trust level of 2, where the system authority will not know the user secret keys since self-certified cryptography is used. In this paper, we demonstrate that any malicious outsider can break the security of Wu and Lin's scheme by impersonating any one of the party using public key replacement attack. Besides, we show that the system authority can easily recover all the user secret keys which contradicts with the concept of self-certified cryptography. Lastly, if the secret key shared between two parties or one of the party's private key had been compromised, the same two users can no longer communicate in the future since the same secret key will be derived and shared forever. This violates the property of forward secrecy, a property that must be provided for a key agreement scheme. [ABSTRACT FROM AUTHOR]

After many searchable symmetric schemes have been proposed and proven secure, a few published work show empirical evidence of successful attacks on all published schemes. The attacks indicate a gap between the current security models and the practical attackers. This work reviews indistin- guishability and semantic security games for SSE. Finally, a new security definition against the practical attacks is proposed and proven to imply current security definitions. [ABSTRACT FROM AUTHOR]

In utilising cloud storage services, the multiplicity of storage can be used to achieve higher security for the data. This work proposes symmetric searchable encryption which utilizes multiple servers to reduce leakage to the storage servers. This is achieved by partitioning the documents and scattering the encrypted blocks onto independent storage providers. Security model for SSE is adapted to fit this environment and a concrete scheme is presented and analysed. [ABSTRACT FROM AUTHOR]

As an extension of identification schemes in multiparty setting, we propose the first definitions and construction for a Group Identity-Based Identification (Group-IBI) scheme. The Group-IBI involves a group manager (GM) that is in charge of a specific group, which in turn manages several group members. The GM's role is not only to control the registration and revocation of the members, but also to performan identification protocol with a verifier as a whole entity, i.e., a group. The Group-IBI scheme that we proposed is potentially suitable for numerous real-world online applications such as e-shopping, e-banking, and e-voting where consensus of all members of a group is required to be derived before proceeding with authentication. In this paper, we propose the first definitions and security models for Group-IBI. We also show the first provablesecure construction that is pairing free by using the Schnorr identity-based identification (IBI) and Schnorr signature. [ABSTRACT FROM AUTHOR]

This study aimed to characterize antimicrobial resistance and virulence genes in multi-drug resistant enterotoxigenic Escherichia coli (ETEC) isolates (n=117) collected from porcine post-weaning diarrhoea cases in Australia (1999-2005). Isolates were serotyped, antibiogram-phenotyped for 12 antimicrobial agents and genotyped by PCR for 30 plasmid-mediated antimicrobial resistance genes (ARGs), 22 intestinal and 38 extraintestinal E. coli virulence genes (VGs). Nine serogroups were identified, the most prevalent being O149 (46.2%), O141 (11.2%) and Ont (31.6%). None of the isolates showed resistance to ceftiofur or enrofloxacin and 9.4% were resistant to florfenicol. No corresponding extended-spectrum/AmpC β-lactamase, fluoroquinolone or floR ARGs were detected. An antimicrobial resistance index (ARI) was calculated from the combined data with a weighting for each antimicrobial agent dependent upon its significance to human health. Serogroup O141 isolates had a significantly higher ARI due to an elevated prevalence of aminoglycoside ARGs and possession of more virulence genes (VGs), including ExPEC or EHEC adhesins (bmaE, sfa/focDE, fimH, ihA) in toxin-producing strains that lacked the normally associated F4 and F18 fimbriae. Few associations between ARGs and VGs were apparent, apart from tetC, sfa/focDE and ompT which, for a sub-set of O141 isolates, suggest possible plasmid acquisition from ExPEC. The multi-drug resistant ETEC ARG/VG profiles indicate a high probability of considerable strain and plasmid diversity, reflecting various selection pressures at the individual farm level rather than emergence and lateral spread of MDR resistant/virulent clones., (Copyright © 2010. Published by Elsevier B.V.)

Introduction: This study sets out to determine the usefulness of a questionnaire to screen for hearing impairment, assess the psychosocial impact of hearing handicap and survey older persons' attitudes towards hearing aid usage., Methods: Subjects were recruited from a Geriatric Medicine unit over a six-month period. A questionnaire was administered, followed by an otoscopic examination and audiometric testing., Results: Sixty-three patients were included in the study. Fifty-two (83%) patients had hearing impairment, of which 34 were moderately severe and 18 were mild. Of the six questions used in hearing screening, the question on self-perception was the most specific (91%). Administering the remaining five questions on activities of daily living improved the questionnaire's sensitivity from 58% to 73%, although the specificity was reduced from 91% to 64%. Of the 30 patients with self-perceived and audiometrically-confirmed hearing impairment, about 40% reported negative psychosocial impact as a result of the handicap. 66.7% were not keen to consider using hearing aid, even if recommended. The willingness to use hearing aids was correlated to patients' functional status (p=0.002) but not to the severity of hearing impairment (p=0.157)., Conclusion: Self-perception of hearing problems in the elderly is a strong indicator of hearing impairment. Introducing additional culturally-relevant questions based on activities of daily living improves the detection rate of hearing impairment. Although hearing loss impacts negatively on psychosocial well-being, most elderly subjects are unwilling to consider the use of hearing aids. There is a need to educate the elderly on the importance of intervention in order to reduce their handicap and improve their quality of life.

Like most cutting edge medical technology, human stem cell research raises a number of difficult and important ethical issues and concerns, requiring potential benefits to be balanced against the need to protect the rights and welfare of citizens. Much of the debate involves research using embryonic stem (ES) cells, which in turns revolves around the moral status of the human embryo, and the level of respect and protection that should be accorded. This is an especially sensitive issue in pluralistic societies where different, if not conflicting, cultural and religious perspectives exist. Another contentious issue as far as the derivation of ES cells is concerned is the intent involved in producing the embryos, specifically whether it is ethically permissible to allowing embryos to be made solely for the purpose of research. These and several other relevant ethical issues will be discussed, including a comparison of guidelines and positions adopted in different countries.

Information Technology (IT) has transformed the ways modern healthcare systems acquire, store, access and communicate medical information. These developments offer significant benefits to patients and healthcare providers, but they give rise to ethical and legal challenges in the protection of patient privacy and confidentiality. The traditional and humanistic concept of doctor-patient relationship is also under threat as IT is used to bypass the need for personal consultations. One effective approach to continue the use of IT in medicine while minimising its potential hazards is through legal reforms and setting public standards for accessibility and expression of patient autonomy. Ultimately, the role and limitations of IT as a tool to pursue the goals of medicine has to be carefully deliberated, clearly defined and judiciously delineated to ensure its effectiveness and safety.

For centuries, physicians have been allowed to interfere and overrule patient's preferences with the aim of securing patient benefit or preventing harm. With the radical rise in emphasis on individual control and freedom, medical paternalism no longer receives unquestioned acceptance by society as the dominant mode for decision-making in health care. But neither is a decision-making approach based on absolute patient autonomy a satisfactory one. A more ethical and effective approach is to enhance a patient's autonomy by advocating a medical beneficence that incorporates patients' values and perspectives. This can be achieved through a model for shared decision making, acknowledging that though the final choices reside ultimately in patients, only through physician beneficence can the patient be empowered to make meaningful decisions that serve them best. For such a model to function effectively, the restoration of trust in doctor-patient relationship and the adoption of patient-centred communication are both crucial.

There is a growing concern that, like in many developed countries, medical practice in Singapore is fast losing its role and status as a profession. The commodification and industrialisation of health care, and weakening of its ethical foundations are among the main forces threatening to deprofessionalise the practice of medicine. To overcome these challenges, an honest and introspective review of the goals of medicine and an affirmation of the ethical values of medicine are needed in order to reinstate the unique role of medicine in our society. Important steps to take include adopting a patient-centred philosophy and practice culture, promoting and emphasising ethical awareness and sensitivity among physicians, and active participation in constructive dialogues to negotiate the social contract of the profession. A more permanent impact may be achieved through cultivation of medical virtues in physicians, and the integration of core elements of medical professionalism into the ethical systems and mission statement of today's health care organisations.

The goals of medicine as a profession dedicated to healing and caring of the sick in a dignified manner depend very much on a stable and trusting doctor-patient relationship. In the last decade, rapid changes in the healthcare delivery system and socio-political climate have resulted in considerable strain on this relationship. What is needed is a reiteration of the fiduciary obligation of the physician and the central role of the patient in the relationship. Concrete steps and changes at the institutional and individual levels need to be taken to preserve the element of trust in the patient-physician covenant. Only then can the medical profession retain the moral dimension of its role in society.

Introduction: Delayed hospital discharge of elderly patients after an acute illness poses significant problems, including bed-blockade, iatrogenesis, and increase in morbidity, dependency and social isolation. The aim of this study was to determine the factors associated with delayed discharge from an acute geriatric unit., Materials and Methods: This was a prospective cohort study involving 172 consecutive non-institutionalised patients, 65 years and older, admitted to an acute geriatric unit. The medical, functional, psychological and social variables of each subject were documented and any decline in functional status recorded. Based on the discharge status, patients were dichotomised into the "delayed" and "non-delayed" groups. Initial bivariate analyses of the variables were performed to select those associated with the "delayed discharge" group at the P < 0.05 levels. These variables were in turn entered into a multivariate logistic regression model to identify factors significantly associated with delayed discharge., Results: Forty-eight patients (27.9%) had their discharge from the acute geriatric care unit delayed despite clinically fit to be so. Variables significantly associated with delayed discharge in the multivariate model were: 1) decline in basic activities of daily living (ADL) status [P < 0.001; adjusted odds ratio (AOR), 3.63; 95% confidence interval (CI), 1.33 to 9.86] and 2) need for skilled nursing [P = 0.012; AOR, 4.57; 95% CI, 1.88 to 11.14]., Conclusions: The study demonstrates the central importance of effectively identifying elderly patients who are at risk of delayed discharge after acute hospitalisation through a multidisciplinary focus on illness-induced functional decline. It is likely therefore that proactive approaches to rehabilitation and caregiver training, and adequate community-based services, may facilitate early and effective return of these patients to their homes, thereby reducing inappropriate use of acute beds.

A prospective study was carried out to determine the prevalence of swallowing impairment and feeding dependency in an acute geriatric medicine unit in Singapore and the co-morbidity associated with it. A total of 211 patients were assessed over a 3-month period. Only 7.1% of patients gave a history of swallowing impairment prior to hospitalisation. We found that 29.4% of patients on admission and 28.2% on discharge had swallowing impairment, with a mortality of 8.1%. The prevalence of feeding dependency, as defined by the need for feeding assistance or tube feeding, was 26.5% before admission and 27.8% on discharge. The mode of feeding between the time of admission and discharge was changed in 14.9% of patients in response to the evolving medical condition. Swallowing impairment was significantly associated with the presence of dehydration (RR = 2.82, CI = 1.74-4.57), chest infection on admission (RR = 2.85, CI = 1.85-4.41), development of nosocomial chest infection (RR = 6.75, CI = 2.60-17.5), discharge to institutional care (RR = 2.8, CI = 1.51-3.47) and increased mortality (RR = 3.77, CI = 1.45-9.70). We concluded that swallowing impairment and feeding dependency are common in the elderly admitted to an acute geriatric unit. As elderly patients seldom inform clinicians of any underlying swallowing impairment and in view of the increased morbidity and mortality associated with this disability, it is important to screen for swallowing impairment. The high prevalence of feeding dependency adds to the burden of care in the ill elderly.

This article familiarizes the reader with AIDS among Asians and Pacific Islanders (A&PIs) in New York City. The first section describes the epidemiology of AIDS among A&PIs in the United States and in New York City. In the United States 4,131 A&PIs have been diagnosed with AIDS. The age at diagnosis in the United States has been relatively stable over the past decade, although the proportion of diagnoses represented by older A&PIs (aged 40 to 49) has been increasing in New York City. The proportion of heterosexual diagnoses have been relatively stable over the past 6 years, whereas other racial groups have shown increases in the proportion of heterosexual transmissions. Data on defining opportunistic infections suggest that a different clinical pattern exists among A&PIs when compared with other racial groups diagnosed in New York City and the United States whereby A&PIs exhibit the highest proportion of Pneumocystis carinii pneumonia of all groups. The second section provides a discussion of some of the issues facing HIV positive A&PIs and their families in the process of accessing services at community-based HIV service organizations in New York City. One broad concept emerged from the client focus group that served to organize the analysis: family--a compelling case for HIV service organizations to initiate, expand, and maintain family services, however family is defined. The location of A&PI AIDS service organizations and its implications for recentering families in the caregiving process is discussed.

We have made antigen-specific cytotoxic reagents by conjugating the chimeric antibody BR96 (chiBR96) to Pseudomonas exotoxin A (PE), as either native PE or a truncated form (LysPE40) devoid of the cell-recognition region (domain I). PE kills cells by ADP-ribosylation of elongation factor 2, thereby inhibiting protein synthesis. Chimeric BR96 immunotoxins were constructed by chemical conjugation of the toxin to Fab', F(ab')2, and intact IgG and purified by anion-exchange and gel-filtration chromatography. Chimeric BR96 [IgG and F(ab')2] immunotoxins were cytotoxic against tumor cell lines displaying the BR96 antigen, with EC50 values ranging from 0.1 to 110 pM. Immunotoxins constructed with chiBR96 Fab' were 50-100-fold less cytotoxic. Competition analysis showed that the immunotoxins were specifically active through their BR96 antigen-binding ability. The binding of chiBR96-PE and chiBR96-LysPE40 to antigen was equivalent to that of BR96 itself and these immunotoxins were found to internalize very rapidly, displaying 90% of their cytotoxicity within 1 h. Binding assays determined that chiBR96 F(ab')2-LysPE40 bound as well as chiBR96-LysPE40; however, chiBR96 Fab'-LysPE40 bound 20-fold less efficiently. The chiBR96 Fab'-LysPE40 internalized similarly to the F(ab')2 or the IgG immunotoxins. Therefore, the chiBR96 Fab'-LysPE40 immunotoxin is less cytotoxic toward target cells because of reduced antigen binding. This is may be due to the monovalent nature of chiBR96 Fab'-LysPE40. This study shows that the monoclonal antibody chiBR96-Pseudomonas exotoxin A immunotoxins can be effective at inhibiting protein synthesis in target cells.

The effects of pH on the intrinsic fluorescence of purified human erythrocyte glucose transporter (HEGT) were studied to deduce the structure and the ligand-induced dynamics of this protein. D-Glucose increases tryptophan fluorescence of HEGT at a 320-nm peak with a concomitant reduction in a 350-nm peak, suggesting that glucose shifts a tryptophan residue from a polar to a nonpolar environment. Cytochalasin B or forskolin, on the other hand, only produces a reduction at the 350-nm peak. The pH titration of the intrinsic fluorescence of HEGT revealed that at least two tryptophan residues are quenched, one with a pKa of 5.5, the other with a pKa of 8.2, indicating involvement of histidine and cysteine protonation, respectively. D-Glucose abolishes both of these quenchings. Cytochalasin B or forskolin, on the other hand, abolishes the histidine quenching but not the cysteine quenching and induces a new pH quenching with a pKa of about 4, implicating involvement of a carboxyl group. These results, together with the known primary structure and the transmembrane disposition of this protein, predict the dynamic interactions between Trp388 and His337, Trp412 and Cys347, and Trp412 and Glu380, depending on liganded state of HEGT, and suggest the importance of the transmembrane helices 9, 10, and 11 in transport function.

Chemical and functional purity of the human erythrocyte glucose transporter preparation obtained by DEAE column chromatography after octyl glucoside solubilization was assessed. The cytochalasin B binding capacity of the preparation indicates that the preparation is 60-85% functional glucose transporter. Gel filtration chromatography on TSK 250 column separates this preparation into at least three major peptide fractions, namely, P0, P1 and P2, with apparent Mr of approx. 80 000, 43 000 and 17 000, respectively. When the preparation is photolabelled with [3H]cytochalasin B prior to the separation only P0 and P1 are labelled. Exposure of the preparation to octyl glucoside or to ultraviolet light irradiation results in an increase in P0 in a time-dependent manner with a concomitant and proportional reduction in P1, without affecting P2 appreciably. For individual preparations, relative abundance of P0 and P1 vary widely in a reciprocal fashion, while that of P2 is practically fixed at approx. 10% of the total protein. The specific activity of cytochalasin B binding of each preparation correlates linearly with the relative abundance of P1 of the preparation, which gives a calculated specific binding activity of 22 nmol/mg protein for this fraction. These results indicate that P1 and P0 are native and denatured transporter, respectively, while P2 is contaminating protein impurities. These results demonstrate that the glucose transporter preparation contains approx. 10% of nontransporter protein impurities, with a varying amount (up to 30%) of denatured transporter, and that the transporter free of the chemical impurities and the denatured transporter can be obtained by a gel filtration chromatography of this preparation.