Generating operation specifications from UML class diagrams: A model transformation approach

One of the more tedious and complex tasks during the specification of conceptual schemas (CSs) is modeling the operations that define the system behavior. This paper aims to simplify this task by providing a method that automatically generates a set of basic operations that complement the static aspects of the CS and suffice to perform all typical life-cycle create/update/delete changes on the population of the elements of the CS. Our method guarantees that the generated operations are executable, i.e. their executions produce a consistent state wrt the most typical structural constraints that can be defined in CSs (e.g. multiplicity constraints). In particular, our method takes as input a CS expressed as a Unified Modeling Language (UML) class diagram (optionally defined using a profile to enrich the specification of associations) and generates an extended version of the CS that includes all necessary operations to start operating the system. If desired, these basic operations can be later used as building blocks for creating more complex ones. We show the formalization and implementation of our method by means of model-to-model transformations. Our approach is particularly relevant in the context of Model Driven Development approaches.     

Recurrent gains of 1q, 8 and 12 in the Ewing family of tumours by comparative genomic hybridization

Comparative genomic hybridization (CGH) was used to detect copy number changes of DNA sequences in the Ewing family of tumours (ET). We analysed 20 samples from 17 patients. Fifteen tumours (75%) showed copy number changes. Gains of DNA sequences were much more frequent than losses, the majority of the gains affecting whole chromosomes or whole chromosome arms. Recurrent findings included copy number increases for chromosomes 8 (seven out of 20 samples; 35%), 1q (five samples; 25%) and 12 (five samples; 25%). The minimal common regions of these gains were the whole chromosomes 8 and 12, and 1q21-22. High-level amplifications affected 8q13-24, 1q and 1q21-22, each once. Southern blot analysis of the specimen with high-level amplification at 1q21-22 showed an amplification of FLG and SPRR3, both mapped to this region. All cases with a gain of chromosome 12 simultaneously showed a gain of chromosome 8. Comparison of CGH findings with cytogenetic analysis of the same tumours and previous cytogenetic reports of ET showed, in general, concordant results. In conclusion, our findings confirm that secondary changes, which may have prognostic significance in ET, are trisomy 8, trisomy 12 and a gain of DNA sequences in 1q.     

The detection of the sleep apnea syndrome in a population of professional drivers

The aim of this study was to reduce the risk of traffic accidents related to obstructive sleep apnea syndrome (OSAS) by means its detection and treatment in a group of 100 commercial drivers from Seville. Besides, to analyze which clinical findings could suggest OSAS. By means a questionnaire we selected subjects without (questionnaire score < 10 points) and with (questionnaire score > or = 10) clinical history of OSAS. In cases with score > or = 10, an overnight home polygraphy was carried out (Apnoescreen II, Jaeger), with measurement of oronasal airflow, chest and abdominal movements, oxygen saturation, electrocardiogram, body position and actimetry. We performed a manual analysis of recordings, and polygraphy was considered to be positive for OSAS if both AHI (respiratory events Index) or DI (desaturation Index) were > or = 10. In these positive cases, overnight conventional polysomnography was carried out (SleepLab, Jaeger), with therapeutic tests with CPAP if OSAS was diagnosed (AHI > or = 10). Average age and BMI (Body Mass Index) were 41.5 +/- 0.9 years and 28.2 +/- 0.4 kg/m2. Questionnaire was positive in 59 subjects, in 35 of whom home polysomnography was done. We did not find differences in age, BMI, neck circumference or symptomatology among these 35 drivers and the 24 remaining subjects in whom home polygraphy was not performed. Home polygraphy was positive in 10 subjects and negative In 25. Drivers in first group were older, heavier and complaint more frequently about snoring, sleep apnea and daytime sleepiness. We did not find differences in neck circumference, waist/hip ratio nor alcohol consumption between both groups. From the group with positive polygraphy, we performed conventional polysomnography in 8 cases and OSAS was diagnosed in 5 (in all cases, treatment with CPAP was started). This study does not provide data about prevalence, but it seems that the percentage of our drivers with OSAS could be lightly higher than the prevalence in general population. These subjects seem to be older, heavier and complaint more frequently about snoring, sleep apnea and daytime sleepiness.     

Address Generation Optimization for Embedded High-Performance Processors: A Survey

Nowadays embedded systems are growing at an impressive rate and provide more and more sophisticated applications characterized by having a complex array index manipulation and a large number of data accesses. Those applications require high performance specific computation that general purpose processors can not deliver at a reasonable energy consumption. Very long instruction word architectures seem a good solution providing enough computational performance at low power with the required programmability to speed up the time to market. Those architectures rely on compiler effort to exploit the available instruction and data parallelism to keep the data path busy all the time. With the density of transistors doubling each 18 months, more and more sophisticated architectures with a high number of computational resources running in parallel are emerging. With this increasing parallel computation, the access to data is becoming the main bottleneck that limits the available parallelism. To alleviate this problem, in current embedded architectures, a special unit works in parallel with the main computing elements to ensure efficient feed and storage of the data: the address generator unit, which comes in many flavors. Future architectures will have to deal with enormous memory bandwidth in distributed memories and the development of address generators units will be crucial for effective next generation of embedded processors where global trade-offs between reaction-time, bandwidth, energy and area must be achieved. This paper provides a survey of methods and techniques that optimize the address generation process for embedded systems, explaining current research trends and needs for future.

Propagation delay influence in IEEE 802.11 outdoor networks

Originally, Wireless Local Area Networks served only small indoor areas. Nevertheless, the idea of employing IEEE 802.11 networks in large outdoor environments is a very attractive possibility. IEEE 802.11 technology offers several advantages: the low cost of equipment, its operation in the unlicensed spectrum and its higher data rates. Since the advent of the first IEEE 802.11 standard, a great deal of research has been carried out. So-called Wifi-based Long Distance networks are currently being deployed. In this paper, we study the suitability of employing IEEE 802.11 networks in large outdoor environments without modifying the standard working procedure. In such scenarios, IEEE 802.11 networks should offer coverage ranges of several kilometer, which leads to high propagation delay values. Thus, we analyze the influence of increasing propagation delay in the IEEE 802.11 MAC protocol. To carry out our analysis we present a mathematical model and simulation results. We provide an operating range in which IEEE 802.11 performance is feasible and establish a throughput threshold according to the propagation delay.     

A Fittingness Factor-Based Spectrum Management Framework for Cognitive Radio Networks

In order to increase cognitive radios (CRs) operation efficiency, there has been an increasing interest in strengthening awareness level about spectrum utilisation. In this respect, this paper proposes to exploit the fittingness factor concept to capture the suitability of spectral resources exhibiting time-varying characteristics to support a set of heterogeneous CR applications. First, a new knowledge management functional architecture for optimizing spectrum management has been constructed. It integrates a set of advanced statistics capturing the influence of the dynamic radio environment on the fittingness factor. Then, a knowledge manager (KM) exploiting these statistics to monitor time-varying suitability of spectrum resources has been proposed to support the spectrum selection (SS) decision-making process. In particular, a new Fittingness Factor-based strategy combining two SS and spectrum mobility (SM) functionalities has been proposed, following either a greedy or a proactive approach. Results have shown that, with a proper fittingness factor function, the greedy approach efficiently exploits the KM support at low loads and the SM functionality at high loads to introduce significant gains in terms of the user dissatisfaction probability. The proactive approach has been shown to maintain the introduced performance gain while minimizing the signalling requirements in terms of spectrum handover rate.     

Design and implementation of a lightweight online certificate validation service

A PKI (public key infrastructure) provides for a digital certificate that can identify an individual or an organization. However, the existence of a certificate is a necessary but not sufficient evidence for its validity. The PKI needs to provide applications that use certificates with the ability to validate, at the time of usage, that a certificate is still valid (not revoked). One of the two standard protocols to check the revocation status of certificates is the Online Certificate Status Protocol (OCSP). In this article, we propose an OCSP-based implementation that enhances the performance of standard OCSP. In particular, we put special emphasis on those issues that affect security and performance when the validation service is deployed in a real scenario. Finally, we provide experimental results that show that our implementation outperforms standard OCSP.     

Expression of transporter associated with antigen processing-1 in the endocrine cells of human pancreatic islets: effect of cytokines and evidence of hyperexpression in IDDM

Increased knowledge of the biochemical composition of the glomerular basement membrane (GBM) and the introduction of molecular genetics has shed new light on the hereditary disorders of the GBM. In this review three disorders are highlighted. About 85% of the cases reported as Alport syndrome are transmitted as the X-linked form and are due to mutations of the COl4A5 chain localized at Xq22. The autosomal recessive form can be explained by mutations in the COl4A3 and COl4A4 gene. Anti-GBM nephritis leading to loss of the renal allograft in about 1%-5% of transplanted Alport patients can be the tragic consequence of this disorder. Some patients with familial benign hematuria have an abnormality of COl4A4. The nail-patella syndrome is a rare autosomal dominant disorder defined by the association of nail dysplasia, bone abnormalities, and frequently renal disease. The gene is localized in region 9q34.1, COl5A1 is not involved. The Finnish type is the best known of the different forms of congenital nephrotic syndrome. The gene has been mapped to the long arm of chromosome 19. Diffuse mesangial sclerosis occurs in the isolated form and as part of the Denys Drash syndrome. Disturbances of the WT1 function in the epithelial cells can have a role in the renal abnormalities of the Denys Drash syndrome.