New multiparty authentication services and key agreement protocols

Many modern computing environments involve dynamic peer groups. Distributed simulation, multiuser games, conferencing applications, and replicated servers are just a few examples. Given the openness of today's networks, communication among peers (group members) must be secure and, at the same time, efficient. This paper studies the problem of authenticated key agreement in dynamic peer groups with the emphasis on efficient and provably secure key authentication, key confirmation, and integrity. It begins by considering two-party authenticated key agreement and extends the results to group Diffie-Hellman (1976) key agreement. In the process, some new security properties (unique to groups) are encountered and discussed     

Conjointanalyse-basierte Produkt(linien)gestaltung unter Berücksichtigung von Konkurrenzreaktionen Conjoint-based product (line) design considering competitive reactions

Ausgangspunkt unserer Untersuchungen zur Conjointanalyse-basierten wettbewerbsorientierten Produktgestaltung bilden segmentspezifische konditionale MNL-Modelle. Bisher auf diesem Gebiet entwickelte Ans?tze, die sich mit der Bestimmung von Marktgleichgewichten befassen, beschr?nken sich ausschlie?lich auf den Single-Produkt-Fall (z.B. Choi u. DeSarbo, 1993; Green u. Krieger, 1997). Unser Beitrag setzt sich ebenfalls mit dem Single-Produkt-Fall (d.h. ein Produkt je Anbieter) auseinander, behandelt darüber hinaus erstmals aber auch den Wettbewerb mit Produktlinien. Gegenstand der Untersuchungen sind insbesondere die Existenz und Eindeutigkeit simultaner Positions-Preis- Gleichgewichte, die Existenz ineffizienter Marktgleichgewichte sowie der Differenzierungsgrad zwischen Konkurrenzprodukten.     

Gender dysphoria, gender reorientation, and the clinical management of transsexualism.

Conducted 2 studies of gender dysphoria and postoperative adjustment by transsexuals. Study 1 examined the relation of gender reorientation (approximation of the status of the opposite biological sex) to psychological adjustment in gender dysphorics. Three S groups (75 heterosexual males, mean age 36.7 yrs; 85 homosexual males, mean age 29.8 yrs; and 103 biological females, mean age 27.4 yrs) were studied in multiple regression analyses, with psychological symptoms as criteria and measures of 3 roughly sequential components of gender reorientation (role changes, document changes, and physical changes), age, and education as predictors. Psychological complaints correlated negatively with the earliest phase of reorientation for females and with the later phases for males. Age and education bore little relation to current symptoms. Results suggest that psychological improvement accompanies gender reorientation in both male and female gender dysphorics; the greatest degree of improvement is seen earlier in the process for females. Ss in Study 2 were postoperative transsexuals (32 homosexual males, mean age 33.2 yrs; 9 heterosexual males, mean age 47.7 yrs; and 38 biological females, mean age 32.6 yrs) at least 1 yr after surgery. Follow-up rate was 77.5% for all Ss meeting the 1-yr criterion. Satisfaction with surgery was high, and psychosocial adjustment was acceptable for the majority. Results of both studies support the rationale for clinical intervention in aid of gender reorientation in selected cases. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Referate

Ohne Zusammenfassung     

Analysis of recovery from behavioral asymmetries induced by unilateral removal of vibrissae in the rat.

Unilateral removal of vibrissae in rats induces an asymmetry in the side of the face used to scan the wall while traversing the edge of an open field (thigmotactic scanning). This behavioral asymmetry recovers over time. The time course of asymmetry and recovery was systematically analyzed by testing groups of rats deprived of vibrissae for different periods of time. The preferential use of the hemiface with intact vibrissae persisted up to 3 days after vibrissae removal. It was expressed maximally during the first minute of testing. This phase was followed by a rapid return to symmetry by Day 6. Recovery to symmetry involved both a decrease in duration of scanning with the vibrissae-intact side and an increase with the vibrissae-clipped side of the face, with the total duration remaining constant throughout the states of asymmetry and recovery. The time course of behavioral recovery corresponds to the time course of neural plasticity in the basal ganglia that accompanies hemivibrissotomy, a result suggesting a functional link between the two phenomena. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition memory impairment in Parkinson's disease: Power and meta-analyses.

Contrary findings notwithstanding, the prevailing notion is that recognition memory is little affected by Parkinson's disease (PD). Both a power analysis and a meta-analysis were conducted to help clarify the degree of recognition memory deficit associated with PD. The power analysis confirmed that, in general, memory studies of PD participants have been underpowered. This analysis indicated the need to pool study results in a subsequent meta-analysis, the main finding of which was that recognition memory deficits do occur with PD. The largest deficit occurs in PD participants with dementia. Nevertheless, deficits also occur in PD participants without dementia on medication, but nondopaminergic central nervous system abnormalities are more likely to underlie this deficit than PD medication itself. Future development of a theory of cognitive dysfunction in PD should take into account these recognition memory deficits, which may increase with disease progression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intercomparison of the Realizations of the ITS-90 from 83.8058 K to 692.677 K among European NMIs

The EUROMET.T-K3 comparison is the regional extension of CCT-K3. The comparison involved the six European national metrology institutes (NMIs) previously involved in CCT-K3 (LNE-INM/CNAM, SMU, INRiM, NMi-VSL, NPL, PTB) and 18 additional European national laboratories. The comparison was divided into five different loops, each coordinated by a co-pilot chosen from the laboratories having participated in the CCT-K3 comparison. LNE-INM/CNAM played the role of pilot in linking the five loops. In each loop, an artifact in the form of a standard platinum resistance thermometer (SPRT, 25 Ω) was circulated among the participating laboratories. To have sufficient information about the possible drift of the SPRTs, the co-pilots performed a calibration over the full temperature range at the beginning and at the end of the loop. A EUROMET reference value (ERV), taking into account the whole comparison, was defined, and the differences (T _Lab − T _ERV) were calculated with the associated uncertainties. The method for establishing the link between the participants in CCT-K3 and in EUROMET.T-K3 is described. Institut National de Métrologie (BNM-INM/CNAM at the time of the comparison, LNE-INM/CNAM since 1 January 2005), Paris, France.     

Hysteresis and Related Error Mechanisms in the NIST Watt Balance Experiment

The NIST watt balance experiment is being completely rebuilt after its 1998 determination of the Planck constant. That measurement yielded a result with an approximately 1×10⁻⁷ relative standard uncertainty. Because the goal of the new incarnation of the experiment is a ten-fold decrease in uncertainty, it has been necessary to reexamine many sources of systematic error. Hysteresis effects account for a substantial portion of the projected uncertainty budget. They arise from mechanical, magnetic, and thermal sources. The new experiment incorporates several improvements in the apparatus to address these issues, including stiffer components for transferring the mass standard on and off the balance, better servo control of the balance, better pivot materials, and the incorporation of erasing techniques into the mass transfer servo system. We have carried out a series of tests of hysteresis sources on a separate system, and apply their results to the watt apparatus. The studies presented here suggest that our improvements can be expected to reduce hysteresis signals by at least a factor of 10—perhaps as much as a factor of 50—over the 1998 experiment.