A compositional Semantics for CHR

Constraint Handling Rules (CHR) are a committed-choice declarative language which has been designed for writing constraint solvers. A CHR program consists of multi-headed guarded rules which allow one to rewrite constraints into simpler ones until a solved form is reached. CHR has received a considerable attention, both from the practical and from the theoretical side. Nevertheless, due the use of multi-headed clauses, there are several aspects of the CHR semantics which have not been clarified yet. In particular, no compositional semantics for CHR has been defined so far. In this paper we introduce a fix-point semantics which characterizes the input/output behavior of a CHR program and which is and-compositional, that is, which allows to retrieve the semantics of a conjunctive query from the semantics of its components. Such a semantics can be used as a basis to define incremental and modular analysis and verification tools

Transformations of CCP programs

We introduce a transformation system for concurrent constraint programming (CCP). We define suitable applicability conditions for the transformations which guarantee that the input/output CCP semantics is preserved also when distinguishing deadlocked computations from successful ones and when considering intermediate results of (possibly) non-terminating computations. The system allows us to optimize CCP programs while preserving their intended meaning: In addition to the usual benefits that one has for sequential declarative languages, the transformation of concurrent programs can also lead to the elimination of communication channels and of synchronization points, to the transformation of non-deterministic computations into deterministic ones, and to the crucial saving of computational space. Furthermore, since the transformation system preserves the deadlock behavior of programs, it can be used for proving deadlock freeness of a given program wrt a class of queries. To this aim it is sometimes sufficient to apply our transformations and to specialize the resulting program wrt the given queries in such a way that the obtained program is trivially deadlock free.Comment: To appear in ACM TOPLA

Perceived disability from hearing and voice changes in the elderly

Aim: Dysphonia and hearing loss are underestimated conditions in the elderly, despite their significant prevalence (18% and 50%, respectively) and their sociopsychological implications. Previous studies have shown that the reason for this lack of consideration is related to the general misconception of a simple age-related issue, as well as to the reduced communication requirements of this population, which can result in infrequent requests/supply of care. The purpose of the present study was to evaluate, within an elderly population, the subjective perception of hearing and voice dysfunctions, the resulting changes in communication skills, and the perception of handicap and disability. Methods: Four anonymous questionnaires were administered to 400 participants (218 men, 182 women) aged older than 65 years, some of whom (276) were hospitalized and some of whom (124) were outpatients. The questionnaires consisted of questions regarding age-related changes in voice, multiple-choice questions on the qualitative characteristics of the voice, questions regarding verbo-acoustic communication (hearing), the Voice Handicap Index, and the Self Assessment of Communication regarding the perception of hearing loss-related handicap and disability. Statistical correlations were calculated for voice dysfunction between the perception of disability and the clinical assessment of voice quality obtained by the Grade, Roughness, Breathiness, Asthenia, Strain scale, and between the perception of disability and the demand for care. Results: More than half of the elderly patients reported not perceiving voice changes throughout their lives. Most of the participants were satisfied with their own voices, although 65% of them judged them to be qualitatively altered, and in 31.5% of the participants, pathology was found on phoniatric evaluation. Low scores for vocal handicap (Voice Handicap Index) were found, and the type of perceived disability was mainly physical, although the association between Voice Handicap Index scores and Grade, Roughness, Breathiness, Asthenia, Strain was statistically significant. A total of 62% of the patients perceived hearing changes over their lifetimes not related to previous ear infections, but significantly correlated with a family history of hearing problems and with the need for specialist consultations. However, the perception of hearing loss handicaps and disability showed lower mean values, showing that older patients recognized dysfunction, but did not consider it to be a disability. Conclusions: The present study showed that, despite the relevant incidence of hearing and voice disorders among the elderly population, the implications for communication abilities seems to be underestimated. Hence, it appears to be extremely important to undergo specialist screening consultations to detect eventual voice and hearing alterations, and to correct them with appropriate therapeutic strategies

On the Expressive Power of Multiple Heads in CHR

Constraint Handling Rules (CHR) is a committed-choice declarative language which has been originally designed for writing constraint solvers and which is nowadays a general purpose language. CHR programs consist of multi-headed guarded rules which allow to rewrite constraints into simpler ones until a solved form is reached. Many empirical evidences suggest that multiple heads augment the expressive power of the language, however no formal result in this direction has been proved, so far. In the first part of this paper we analyze the Turing completeness of CHR with respect to the underneath constraint theory. We prove that if the constraint theory is powerful enough then restricting to single head rules does not affect the Turing completeness of the language. On the other hand, differently from the case of the multi-headed language, the single head CHR language is not Turing powerful when the underlying signature (for the constraint theory) does not contain function symbols. In the second part we prove that, no matter which constraint theory is considered, under some reasonable assumptions it is not possible to encode the CHR language (with multi-headed rules) into a single headed language while preserving the semantics of the programs. We also show that, under some stronger assumptions, considering an increasing number of atoms in the head of a rule augments the expressive power of the language. These results provide a formal proof for the claim that multiple heads augment the expressive power of the CHR language.Comment: v.6 Minor changes, new formulation of definitions, changed some details in the proof

Sugar and chromosome stability: Clastogenic effects of sugars in vitamin B6-deficient cells

Pyridoxal 5'-phosphate (PLP), the active form of vitamin B6, has been implicated in preventing human pathologies, such as diabetes and cancer. However, the mechanisms underlying the beneficial effects of PLP are still unclear. Using Drosophila as a model system, we show that PLP deficiency caused either by mutations in the pyridoxal kinase-coding gene (dPdxk) or by vitamin B6 antagonists results in chromosome aberrations (CABs). The CAB frequency in PLP-depleted cells was strongly enhanced by sucrose, glucose or fructose treatments, and dPdxk mutant cells consistently displayed higher glucose contents than their wild type counterparts, an effect that is at least in part a consequence of an acquired insulin resistance. Together, our results indicate that a high intracellular level of glucose has a dramatic clastogenic effect if combined with PLP deficiency. This is likely due to an elevated level of Advanced Glycation End-products (AGE) formation. Treatment of dPdxk mutant cells with alpha lipoic acid (ALA) lowered both AGE formation and CAB frequency, suggesting a possible AGE-CAB cause-effect relationship. The clastogenic effect of glucose in PLP-depleted cells is evolutionarily conserved. RNAi-mediated silencing of PDXK in human cells or treatments with PLP inhibitors resulted in chromosome breakage, which was potentiated by glucose and reduced by ALA. These results suggest that patients with concomitant hyperglycemia and vitamin B6 deficiency may suffer chromosome damage. This might impact on cancer risk, as CABs are a well-known tumorigenic factor

Timed Soft Concurrent Constraint Programs: An Interleaved and a Parallel Approach

We propose a timed and soft extension of Concurrent Constraint Programming. The time extension is based on the hypothesis of bounded asynchrony: the computation takes a bounded period of time and is measured by a discrete global clock. Action prefixing is then considered as the syntactic marker which distinguishes a time instant from the next one. Supported by soft constraints instead of crisp ones, tell and ask agents are now equipped with a preference (or consistency) threshold which is used to determine their success or suspension. In the paper we provide a language to describe the agents behavior, together with its operational and denotational semantics, for which we also prove the compositionality and correctness properties. After presenting a semantics using maximal parallelism of actions, we also describe a version for their interleaving on a single processor (with maximal parallelism for time elapsing). Coordinating agents that need to take decisions both on preference values and time events may benefit from this language. To appear in Theory and Practice of Logic Programming (TPLP)

Bone conductive implants in single sided deafness

Conclusion: The Bone Conductive Implants (BCI) showed to partly restore some of the functions lost when the binaural hearing is missing, such as in the single-sided deafness (SSD) subjects. The adoption of the single BCI needs to be advised by the clinician on the ground of a thorough counselling with the SSD subject. Objectives: To perform an overview of the present possibilities of BCI in SSD and to evaluate the reliability of the audiological evaluation for assessing the speech recognition in noise and the sound localization cues, as major problems related to the loss of binaural hearing. Method: Nine SSD subjects who underwent BCI implantation underwent a pre-operative audiological evaluation, consisting in the soundfield speech audiometry, as word recognition score (WRS) and sound localization, in quiet and in noise. Moreover, they were also tested for the accuracy of directional word recognition in noise and with the subjective evaluation with APHAB questionnaire. Results: The mean maximum percentage of word discrimination was 65.5% in the unaided condition and 78.9% in the BCI condition. The sound localization in noise with the BCI was better than the unaided condition, especially when stimulus and noise were on the same side of the implanted ear. The accuracy of directional word recognition showed to improve with BCI in respect to the unaided condition, in the BCI side, with either the stimulus on the implanted ear and the noise in the contralateral ear, or when both stimulus and noise were deliver to implanted ear

Inner Ear Active Hearing Device in Non-Otosclerotic, Severe, Mixed Hearing Loss

OBJECTIVE: To verify the efficacy of a powerful active hearing device in a patient different from far-advanced otosclerosis, specifically when the stapes footplate is mobile. PATIENT: A patient with severe-to-profound mixed hearing loss, who was not benefiting from the use of a conventional hearing aid, was selected for an inner ear active implant. This was justified by a bone conductive threshold above 60 dB, which had discouraged any other rehabilitative solutions such as a bone conductive implant, or an active middle ear implant (AMEI). INTERVENTION: The hearing device was surgically applied using a combined transmastoid/transcanal approach. During surgery, a mobile stapes were found and was perforated for the insertion of a piston prosthesis, crimped on the new-incus of the device. MAIN OUTCOME MEASURE: The bone conduction threshold was assessed postoperatively to identify any possible surgery-related hearing deterioration. Pure tone audiometry was conducted in a sound field, and a speech reception threshold test was performed with the contralateral ear masked. The hearing outcome was assessed soon after the implant activation (6 weeks after surgery), and 6 months after surgery. RESULTS: Upon activation of the device, a PTA of 45 dB was obtained (at 0.5, 1, 2 and 4 kHz). At 6 months after surgery, the speech discrimination score reached 90% at 80 dB SPL. CONCLUSION: The application of the Codacs device has shown to be compatible with a mobile stapes footplate, as demonstrated in this report. The footplate perforation did not cause any further hearing deterioration, and has allowed to achieve a favorable auditory outcome

Mental sleep activity and disturbing dreams in the lifespan

Sleep significantly changes across the lifespan, and several studies underline its crucial role in cognitive functioning. Similarly, mental activity during sleep tends to covary with age. This review aims to analyze the characteristics of dreaming and disturbing dreams at dierent age brackets. On the one hand, dreams may be considered an expression of brain maturation and cognitive development, showing relations with memory and visuo-spatial abilities. Some investigations reveal that specific electrophysiological patterns, such as frontal theta oscillations, underlie dreams during sleep, as well as episodic memories in the waking state, both in young and older adults. On the other hand, considering the role of dreaming in emotional processing and regulation, the available literature suggests that mental sleep activity could have a beneficial role when stressful events occur at dierent age ranges. We highlight that nightmares and bad dreams might represent an attempt to cope the adverse events, and the degrees of cognitive-brain maturation could impact on these mechanisms across the lifespan. Future investigations are necessary to clarify these relations. Clinical protocols could be designed to improve cognitive functioning and emotional regulation by modifying the dream contents or the ability to recall/non-recall them

The functional role of dreaming in emotional processes

Dream experience (DE) represents a fascinating condition linked to emotional processes and the human inner world. Although the overlap between REM sleep and dreaming has been overcome, several studies point out that emotional and perceptually vivid contents are more frequent when reported upon awakenings from this sleep stage. Actually, it is well-known that REM sleep plays a pivotal role in the processing of salient and emotional waking-life experiences, strongly contributing to the emotional memory consolidation. In this vein, we highlighted that, to some extent, neuroimaging studies showed that the processes that regulate dreaming and emotional salience in sleep mentation share similar neural substrates of those controlling emotions during wakefulness. Furthermore, the research on EEG correlates of the presence/absence of DE and the results on EEG pattern related to the incorporated memories converged to assign a crucial role of REM theta oscillations in emotional re-processing. In particular, the theta activity is involved in memory processes during REM sleep as well as during the waking state, in line with the continuity hypothesis. Also, the gamma activity seems to be related to emotional processes and dream recall as well as to lucid dreams. Interestingly, similar EEG correlates of DE have been found in clinical samples when nightmares or dreams occur. Research on clinical samples revealed that promoting the rehearsal of frightening contents aimed to change them is a promising method to treat nightmares, and that lucid dreams are associated with an attenuation of nightmares. In this view, DE can defuse emotional traumatic memories when the emotional regulation and the fear extinction mechanisms are compromised by traumatic and frightening events. Finally, dreams could represent a sort of simulation of reality, providing the possibility to create a new scenario with emotional mastery elements to cope with dysphoric items included in nightmares. In addition, it could be hypothesized that the insertion of bizarre items besides traumatic memories might be functional to “impoverish” the negative charge of the experiences