Complexity of Regular Language Matching and Other Decidable Cases of the Satisfiability Problem for Constraints Between Regular Open Terms

In this paper we study the satisfiability problem for language equations and constraints between regular open terms. We prove that: the constraint problem is PSPACE-complete, the regular language matching problem is EXPSPACE-complete even if we ask about satisfiability by regular languages, satisfiability of word-like language equations is in PSPACE, the finite solution problem is EXPSPACE-complete.     

Studying endocytosis in space and time by means of temporal Boolean models

Endocytosis is a process by which cells carry traffic from the extracellular space into various intracellular compartments. Visualization of fluorescently tagged clathrin proteins (mediators of endocytosis) allows us to image endocytosis in real time. When imaging the plasma membrane, areas of fluorescence generated by different endocytic processes overlap spatially and temporally, forming random clumps. Here, a sequence of segmented clathrin spots is considered a realization of a non-isotropic 3D Boolean model. Estimates of the intensity, the mean perimeter and the density function of the durations of endocytic events are obtained.     

Differences on post-thawing survival between ovine morulae and blastocysts cryopreserved with ethylene glycol or glycerol

Embryos were collected on Days 5 and 6 after breeding to investigate the effectiveness of ethylene glycol (ETG) and glycerol (GLY) as cryoprotectants of sheep morulae and blastocysts and to determine their optimum stage of development for cryopreservation. Only excellent (grade 1) and good (grade 2) embryos (196 morulae and 188 blastocysts) were incubated in increasing concentrations of GLY or ETG and submitted to a slow-freezing and quick-thawing procedure. Both cryoprotectants were removed using 0.25 M sucrose solution, and then embryos were cultured or transferred to determine their viability. Freezing medium containing ETG yielded higher in vitro survival rates (P < 0.01) than medium containing GLY (64.6% vs 16.0%); the difference between cryoprotectants was greater when morulae were used (57.9% vs 4.2%, P < 0.005) as compared with blastocysts (70.4% vs 21.5%, P < 0.05). There was a strong interaction between type of cryoprotectant and embryo stage (P < 0.005). After transfer of morphologically viable embryos, the in vivo development rate of embryos frozen with ETG was also higher than that of embryos frozen with GLY (45.5% vs 27.7%, P < 0.05). There were no significant differences in the number of lambs born among procedures and embryo stage, though the lowest lambing rate was obtained with morulae frozen with GLY (21.4%). Similar lambing rates were produced when blastocysts were frozen with either GLY or ETG (36.6% vs 43.0%). The best embryo survival after thawing was observed when blastocysts were frozen with ETG as cryoprotectant.     

On the Semantics of Deliberation in IndiGolog — from Theory to Implementation

We develop an account of the kind of deliberation that an agent that is doing planning or executing high-level programs under incomplete information must be able to perform. The deliberator's job is to produce a kind of plan that does not itself require deliberation to interpret. We characterize these as epistemically feasible programs: programs for which the executing agent, at every stage of execution, by virtue of what it knew initially and the subsequent readings of its sensors, always knows what step to take next towards the goal of completing the entire program. We formalize this notion and characterize deliberation in the situation calculus based IndiGolog agent programming language in terms of it. We also show that for certain classes of problems, which correspond to those with bounded solutions and those with solutions without sensing, the search for epistemically feasible programs can be limited to programs of a simple syntactic form. Finally, we discuss implementation issues and execution monitoring and replanning too.     

Towards Certificate-Based Authentication for Future Mobile Communications

Certificate-based authentication of parties provides a powerful means for verifying claimed identities, since communicating partners do not have to exchange secrets in advance for authentication. This is especially valuable for roaming scenarios in future mobile communications where users authenticate to obtain network access—service access may potentially be based thereon in integrated approaches—and where the number of access network providers and Internet service providers is expected to increase considerably. When dealing with certificates, one must cope with the verification of complete certificate paths for security reasons. In mobile communications, additional constraints exist under which this verification work is performed. These constraints make verification more difficult when compared to non-mobile contexts. Mobile devices may have limited capacity for computation and mobile communication links may have limited bandwidth. In this paper, we propose to apply PKI servers—such as implemented at FhG-SIT—that allow the delegation of certificate path validation in order to speed up verification. Furthermore, we propose a special structure for PKI components and specific cooperation models that force certificate paths to be short, i.e., the lenghts of certificate paths are upper-bounded to certain small values depending on the conditions of specific cases. Additionally, we deal with the problem of users who do not have Internet access during the authentication phase. We explain how we solved this problem and show a gap in existing standards.     

Deep levels in the band gap of CdTe films electrodeposited from an acidic bath—PICTS analysis

The deep traps detected in a CdTe thin film electrodeposited from an acidic bath are discussed. CdTe thin films were developed on flexible metallic substrates by electro deposition. The films were nearly stiochiometric, highly uniform and exhibit good crystallinity. The films were characterized using XRD, SEM, AUGER and AFM. The crystallites exhibited a strong preference for the (1 1 1) plane. The grain size of the film was in the range 0.2–0.4 μm. The photoinduced current transient spectroscopic technique was effectively used to identify the electron and hole traps. Two hole traps and one electron trap was detected. The activation energies of those deep traps were 0.37 and 0.42 eV for the hole traps and 0.41 eV for the electron trap.     

Comparison of the efficacy of apraclonidine and brimonidine as aqueous suppressants in humans

OBJECTIVE: To measure and compare the effect of apraclonidine hydrochloride and brimonidine tartrate on the rate of aqueous humor flow in human subjects. SUBJECTS AND METHODS: Forty normal human subjects were given apraclonidine or brimonidine by topical instillation. Aqueous humor flow was measured by the rate of disappearance of topically applied fluorescein. Intraocular pressure was measured by applanation tonometry. RESULTS: Apraclonidine suppressed aqueous humor flow between 39% and 44% and lowered intraocular pressure between 20% and 23%. Brimonidine suppressed aqueous humor flow between 44% and 48% and lowered intraocular pressure between 19% and 22%. CONCLUSION: No statistically significant differences were found between the effects of the 2 drugs on aqueous humor dynamics in normal subjects.     

On the asymptotic performance of IDA*

Since best‐first search algorithms such as A* require large amounts of memory, they sometimes cannot run to completion, even on problem instances of moderate size. This problem has led to the development of limited‐memory search algorithms, of which the best known is IDA*. This paper presents the following results about IDA* and related algorithms: 1) The analysis of asymptotic optimality for IDA* in [R.E. Korf, Optimal path finding algorithms, in: Search in Artificial Intelligence, eds. L. Kanal and V. Kumar (Springer‐Verlag, 1988) pp. 200-222] is incorrect. There are trees satisfying the asymptotic optimality conditions given in [R.E. Korf, Optimal path finding algorithms, in: Search in Artificial Intelligence, eds. L. Kanal and V. Kumar (Springer‐Verlag, 1988) pp. 200-222] for which IDA* is not asymptotically optimal. 2) To correct the above problem, we state and prove necessary and sufficient conditions for asymptotic optimality of IDA* on trees. On trees not satisfying our conditions, we show that no best‐first limited‐memory search algorithm can be asymptotically optimal. 3) On graphs, IDA* can perform quite poorly. In particular, there are graphs on which IDA* does Ω(2^2N) node expansions where N is the number of nodes expanded by A*. This revised version was published online in June 2006 with corrections to the Cover Date.     

Measuring quality of nursing home service: residents' perspective

An inventory was developed to measure residents' perceptions of the quality of nursing home service. The content domain and dimensions of the inventory were derived from actual comments of nursing home residents. Independent studies employing a multiple-facility sample of 103 residents and 194 residents from a single institution supported a four-factor structure of the quality of nursing home service--Staff and Environmental Responsiveness, Dependability and Trust, Food-related Services and Resources, and Personal Control. The data provide preliminary support for the measure's reliability and validity so it may be used to study the antecedents and consequences of quality in nursing home service from the residents' perspective.