Modeling birds on wires.

In this paper we introduce a mathematical model to study the group dynamics of birds resting on wires. The model is agent-based and postulates attraction-repulsion forces between the interacting birds: the interactions are "topological", in the sense that they involve a given number of neighbors irrespective of their distance. The model is first mathematically analyzed and then simulated to study its main properties: we observe that the model predicts birds to be more widely spaced near the borders of each group. We compare the results from the model with experimental data, derived from the analysis of pictures of pigeons and starlings taken in New Jersey: two different image elaboration protocols allow us to establish a good agreement with the model and to quantify its main parameters. We also discuss the potential handedness of the birds, by analyzing the group organization features and the group dynamics at the arrival of new birds. Finally, we propose a more refined mathematical model that describes landing and departing birds by suitable stochastic processes.

Capillary zone electrophoresis for determination of vildagliptin (a DPP-4 inhibitor) in pharmaceutical formulation and comparative study with HPLC.

A stability-indicating capillary zone electrophoresis (CZE) method was validated for the determination of vildagliptin (VLG) in pharmaceutical dosage forms using ranitidine hydrochloride (RH) as internal standard. The CZE method was carried out in a fused silica capillary (64.5 cm total length and 56.0 cm effective length, 50 microm i.d.) by applying a potential of 25 kV (positive polarity), hydrodynamic injection by 50 mbar for 5 s and the temperature of the capillary cartridge was 25 degreesC. The selected background electrolyte (BGE) consisted of 25 mM potassium phosphate (pH 8.0) with UV/PDA detection at 207 nm. The electrophoretic separation was obtained within 6 min and was linear in the range of 50-200 microg/mL (r= 0.9994). The specificity and the stability-indicating capability were demonstrated through degradation studies, which also showed that there was no interference of the formulation excipients. The method was validated in accordance to ICH guidelines acceptance criteria for specificity, linearity, precision, accuracy, robustness and system suitability. The proposed method was compared with HPLC method previously validated for this drug, and statistical analysis showed no significant difference between the methods.

[Occupational diseases caused by artificial optical radiation (AOR)]. / Le malattie professionali da radiazioni ottiche artificiali (ROA).

BACKGROUND: Italian national legislation guarantees safety and health for workers exposed to artificial optical radiations (AOR) by Legislative Decree 81/2008. OBJECTIVES AND METHODS: Effects and damages to health resulting from AOR exposure were analyzed from literature data. RESULTS: Ultraviolet radiations (UV), particularly those in the wavelength range between 220 and 310 nm, causes chronic conjunctivitis and kerato-conjunctivitis. Skin cancer caused by UV exposure included basal cell carcinoma, squamous cell carcinoma and melanoma. As regards Infrared Radiations (portion of the spectrum between 780 nm and 1 mm), the biological effect is essentially of thermal nature. Exposure to blue light (portion ofthe spectrum of visible light radiation in a wavelength range between 380 and 550 nm) causes exclusively retinal damage and is considered to be responsible for the development of situations of age-related macular degeneration (AMD). Even if experimental data are available, at the present time there is still no epidemiological evidence of retinal damage caused by blue light. CONCLUSIONS: The forensic criteria for investigating the causality link between occupational exposure to AOR and damage, and the methodology necessary for the assessment process, are reported. Two lists of occupational diseases which were included in the Italian Ministerial Decrees, issued respectively on April 2008 and 11 December 2009, are also considered. Lastly, on the basis of the current existing guidelines and scientific evidence, the authors propose occupational health surveillance protocols for workers exposed to AOR risk.

Optimization versus randomness for car traffic regulation.

We focus on the differences among the analytical optimization of traffic flow on a road network, modeled by a fluid-dynamic approach, and a dynamic random one. In particular, two real urban networks are analyzed: Re di Roma Square, in Rome, and Via Parmenide crossing, in Salerno. With such two examples, it is possible to show that dynamic random algorithms are not the right choice for the improvement of traffic conditions.

[Analysis and evaluation of the visual effort in remote-control public traffic operators working with computer-based equipments]. / Analisi e valutazione dell'impegno visivo in operatori addetti al telecontrollo del traffico pubblico mediante sistemi informatizzati.

The aim of this study is the objective evaluation of the visual effort in 6 public traffic controllers (4 male, 2 female, mean age 29,6), by means of electronic equipment. The electronic equipment quantify the observation distance and the observation time for each controller's occupational visual field. The quantification of these parameters is obtained by the emission of ultrasound at 40 KHz from an emission sensor (placed by the VDT screen) and the ultrasound reception by means of a receiving sensor (placed on the operator's head). The travelling time of the ultrasound (US), as the air speed is known and costant (about 340 m/s), it is used to calculate the distance between the emitting and the receiving sensor. The results show that the visual acuity required is of average level, while accommodation's and convergence's effort vary from average to intense (depending on the visual characteristics of the operator considered), ranging from 26,41 and 43,92% of accommodation and convergence available in each operator. The time actually spent in "near observation within the c.v.p." (Tscr) was maintained in a range from 2h 54' and 4h 05'.

[Dermatitis and VDU work]. / Dermatiti e lavoro con VDT/PC.

Skin disorders like rosacea, seborrhoeic dermatitis, non-specific erythema and acne can be VDU work linked. At present, many environmental and individual causes are involved in the development of these disorders, but the former appear to be the issue to investigate more in depth.

[The preventive ergophthalmic evaluation of work places in call centers: a useful instrument for the prevention of work related asthenopic symptoms]. / La valutazione ergoftalmica preventiva dei posti di lavoro nei call center: un valido strumento di prevenzione dei disturbi astenopici occupazionali.

The study of a correct lay-out of work places equipped with VDT/PC in call centres, if carried out before the beginning of work activities needs an interdisciplinary cooperation among OH&S operators. However, such a preventive evaluation can relevantly reduce onset and severity of asthenopic symptoms frequently reported by this kind of operators. Consequently, such preventive evaluation can avoid the necessity of carrying out those complex and expensive structural lay-out modifications, which are frequently needed to reduce VDT/PC workers' asthenopic symptoms.

[Work efficiency and lighting conditions: an experimental study]. / Efficienza lavorativa e condizioni illuminotecniche: studio sperimentale.

Thirty-two voluntary subjects were selected, not suffering either from any degenerative ophthalmic diseases or refraction and ocular motility alterations. Each subject underwent close visual task experimental sessions (e.g. PC usage), under monitored experimental conditions. Aim of the study is the assessment of working efficiency effects caused by lighting conditions characterized by "according to law" illuminations, yet in presence of high or low luminance ratios in the occupational visual field". An analysis of the data showed that high luminance ratios conditions show a decrease of the performance (decrease overall efficiency, increase in the number of errors and time of execution), which where not detected with low luminance ratios conditions. Asthenopia did not show clear differences, possibly due to the effects of the intense near work which was present in both the experimental sessions.

[Adequacy and reliability of orthoanalyzer Ergovision for job-fitness evaluation]. / Adeguatezza e affidabilità dell'ortoanalizzatore Ergovision nel giudizio di idoneità specifica.

The aim of this research was to evaluate the Ergovision Screener (ES) accuracy e validity by a confrontation with the conventional ophthalmic check (OC), for the medical evaluation of job fitness. A population of 100 VDU operators was considered. Each subject underwent randomly both the ES and the ophthalmic check visit. Several test carried out by the Ergovision Screener were not consistent with the conventional ophthalmic check. In a number of cases, high false positive ratio have been found, which could lead to unnecessary further examinations. For all these reasons we believe that the ES is not an appropriate instrument for the medical evaluation of job fitness.

Chemical Speciation of Selenium and Mercury as Determinant of Their Neurotoxicity.

The antagonism of mercury toxicity by selenium has been well documented. Mercury is a toxic metal, widespread in the environment. The main target organs (kidneys, lungs, or brain) of mercury vary depending on its chemical forms (inorganic or organic). Selenium is a semimetal essential to mammalian life as part of the amino acid selenocysteine, which is required to the synthesis of the selenoproteins. This chapter has the aim of disclosing the role of selenide or hydrogen selenide (Se-2 or HSe-) as central metabolite of selenium and as an important antidote of the electrophilic mercury forms (particularly, Hg2+ and MeHg). Emphasis will be centered on the neurotoxicity of electrophile forms of mercury and selenium. The controversial participation of electrophile mercury and selenium forms in the development of some neurodegenerative disease will be briefly presented. The potential pharmacological use of organoseleno compounds (Ebselen and diphenyl diselenide) in the treatment of mercury poisoning will be considered. The central role of thiol (-SH) and selenol (-SeH) groups as the generic targets of electrophile mercury forms and the need of new in silico tools to guide the future biological researches will be commented.

Eye complaints in the office environment: precorneal tear film integrity influenced by eye blinking efficiency.

To achieve a common base for understanding work related eye complaints in the office environment, it is necessary to merge approaches from indoor air science, occupational health, and ophthalmology. Based on database searches, it is concluded that precorneal tear film (PTF) alteration leads to eye complaints that may be caused by: (1) thermal factors (low relative humidity; high room temperature); (2) demanding task content (attention decreases blinking and widens the exposed ocular surface area); and (3) individual characteristics (for example, tear film alterations, blinking anomalies, gland dysfunctions, and use of contact lenses). These factors and conditions are able to progressively increase water evaporation and faster thinning of the PTF, which causes dryness and dry spot formation on the cornea, possibly followed by corneal and conjunctiva epithelial alterations and eye complaints. Another possible cause of eye complaints is certain irritating chemical compounds, in addition to oxidation mixtures that are formed in reactions between ozone and unsaturated organic compounds (alkenes). The effect may be exacerbated by low relative humidity.

Transesophageal echocardiographic evaluation of the morphologic and hemodynamic cardiac changes during ventricular fibrillation.

To analyze cardiac motion during ventricular fibrillation (VF), we used transesophageal echocardiography to study nine male subjects, aged 44 +/- 7 years, affected by heart disease who have poor left ventricular function, during implantation of an Implantable Cardioverter Defibrillator, when VF is induced several times to determine the defibrillation threshold. Wall and valvular motion, transmitral and transaortic blood flow, and blood echoreflectivity were evaluated in all patients. Moreover, in basal conditions, during VF, 1 and 5 minutes after restoration of basal rhythm, we calculated the left ventricular end-diastolic volume (EDLVV) and area (EDLVA), the left ventricular end-systolic volume and area, the ejection fraction, and the fractional area change with a four-chamber echocardiographic view. At the onset of VF, the myocardium and valves exhibited a chaotic motion. About 10 seconds later the oscillatory movement of the heart walls became more ample and regular; the mitral valve showed a cyclic closure and opening with a forward flow, and the aortic valve exhibited similar behavior, although at a lower intensity. A spontaneous echo contrast appeared inside the atrial and ventricular cavities, gradually becoming an incrt homogeneous mass that was completely flushed away with the restoration of the basal rhythm. When VF started, EDLVV (286 +/- 98 ml) and EDLVA (50 +/- 16.5 cm2) decreased abruptly (EDLVV = 182 +/- 65 ml, p < 0.02; EDLVA = 38 +/- 9.2 cm2,p < 0.05); so did ejection fraction (31.8% +/- 15% versus 11% +/- 5%; p < 0.003) and fractional area change (25.8% +/- 6.5% versus 7% +/- 3.4%; p < 0.001). When the basal rhythm was restored, the heart extended again and EDLVV, EDLVA, ejection fraction, and fractional area change after 1 and 5 minutes were similar to those calculated before induction of VF. This behavior was observed during both the first and last induced VF. Thus during VF, great variations of heart morphology and dynamics, as well as blood echoreflectivity, occur; the heart seems to make attempts to organize its dynamics during the arrhythmia. Repeated episodes of VF and defibrillation with low energies do not seem to worsen left ventricular dynamics even in impaired hearts.

Cardiovascular adaptations to endurance training and detraining in young and older athletes.

In order to evaluate the influence of aging on cardiovascular adaptations to endurance training and detraining, 12 young (range 19-25 years) and 12 older (range 50-65 years) male cyclists were examined during the training and after 2 months of detraining. Twelve young and 12 older healthy sedentary males matched for age and body surface area were used as control groups. Each subject underwent a maximal exercise test using a cycle-ergometer in order to measure maximum oxygen consumption, an M-mode and 2D echocardiography in order to assess left ventricle morphology and systolic function, and a Doppler echocardiography for evaluating the diastolic filling pattern. During the training period both groups of athletes showed higher values of maximum oxygen consumption, left ventricular wall thicknesses, end-diastolic diameter and volume, as well as left ventricular mass, than their control subjects; in the older subjects the adaptation of the heart to aerobic training seems to be obtained mainly through a higher increase in left ventricular diastolic filling. In both groups no significant modifications in the ejection fraction and diastolic function parameters were recorded. After the detraining period the wall thicknesses decreased only in young athletes, while left ventricular mass and end-diastolic diameter and volume reduced only in older athletes. In conclusion, training and detraining induced nearly similar left ventricular morphological modifications in the two age groups, even though greater in the older athletes with respect to the ventricular mass and volume. No relevant differences were observed in the Doppler filling pattern between athletes and sedentary controls.

Ergonomic guidelines for using notebook personal computers. Technical Committee on Human-Computer Interaction, International Ergonomics Association.

In the 1980's, the visual display terminal (VDT) was introduced in workplaces of many countries. Soon thereafter, an upsurge in reported cases of related health problems, such as musculoskeletal disorders and eyestrain, was seen. Recently, the flat panel display or notebook personal computer (PC) became the most remarkable feature in modern workplaces with VDTs and even in homes. A proactive approach must be taken to avert foreseeable ergonomic and occupational health problems from the use of this new technology. Because of its distinct physical and optical characteristics, the ergonomic requirements for notebook PCs in terms of machine layout, workstation design, lighting conditions, among others, should be different from the CRT-based computers. The Japan Ergonomics Society (JES) technical committee came up with a set of guidelines for notebook PC use following exploratory discussions that dwelt on its ergonomic aspects. To keep in stride with this development, the Technical Committee on Human-Computer Interaction under the auspices of the International Ergonomics Association worked towards the international issuance of the guidelines. This paper unveils the result of this collaborative effort.

[Post-traumatic constrictive pericarditis with fast course]. / Péricardite constrictive posttraumatique à évolution rapide.

A case is reported of a 46-year-old male patient who sustained a blunt thoracic injury with an anterior flail chest, and right haemopneumothorax. He was intubated and ventilated because of acute respiratory failure. There were initially no signs suggesting any myocardial injury. It was not before day 20 that the electrocardiogram showed a QS wave in leads V2 and V3. The hypothesis of an antero-septal myocardial infarct was not confirmed by echocardiography, which only revealed slight thickening of the posterior pericardium. From day 50 on, the patient had tachycardia, raised jugular venous pressure, and effort dyspnoea. Echocardiography (day 59) showed an anterior and posterior pericardial effusion (about 500 ml), marked pericardial thickening, and inferior vena caval collapse during inspiration, with normal myocardial wall movements. Drainage pericardiocentesis was therefore carried out, followed by, four days later, a pericardiectomy. A small ecchymosis was found on the anterior aspect of the right ventricle. The pericardium was thickened, fibrous, hyperhaemic, Case is y stuck to the epicardium. Eight months later, echocardiography showed that the posterior pericardium remained thickened, and there was a very small residual effusion. Movements of the septum had returned to normal.

[Lighting condition analysis at work]. / Analisi delle condizioni illuminotecniche nei luoghi di lavoro.

Following a wide review of the national and international technical standards which make up the principal reference points when designing illumination systems for work areas, the most commonly used methods of photometric analysis are examined from both a medical and technical point of view. It can be observed that photometric analysis of the work place, which currently is almost exclusively based on the measurements of illuminance, does not appear to adequately reach the targets set by Occupational Health and Occupational Hygiene, for reasons pertaining to the anatomy and physiopathology of the visual function. Moreover, the procedures applied to evaluate the workers' subjectivity and/or symptomatology, that both in research and during on-site investigations makes use predominantly of self-administered questionnaires, shows some shortcomings in terms of reliability and validity. In conclusion, it is proposed, especially in studies regarding office environments (i) to carry out photometric analysis where primary and secondary luminance is always measured and, if light-linked subjectivity is required (ii) to make available valid and precise questionnaires whose administration be followed by a multivariate data analysis.

[Dermatitis in VDT operators: a review of the literature]. / Dermatiti in operatori a VDT: rassegna della letteratura.

The paper reports studies on the relationship between work with VDT's and dermatitis in the operators. From the first observation in 1979, numerous studies have been carried out to try and explain the reason why some forms of dermatitis like rosacea, eczema seborrhoeic and erythematitis appeared more frequently in VDT operators compared to the general population. The various authors at present consider low indoor air humidity associated with a strong electrostatic field to be essential factors in the occurrence of dermatitis. Laboratory experiments have shown that the presence of a strong electrostatic field does not seem to be important in itself. Similarly, it is agreed that X, UV-A or UV-B radiations do not play any causative role in dermatitis. Further investigations are required to assess the influence of indoor climatic factors and the presence of irritant substances in the air of the working environment.

[The contributions of occupational medicine to ergonomics]. / I contributi della medicina del lavoro all'ergonomia.

Major contributions to the development of ergonomics, originating from observations, studies, research and applications in numerous working situations in the occupational health area, are presented and discussed in an analytical and concise manner. Ergonomics can provide an extremely useful conceptual and methodological approach provided it complies with the trends developed by the European Coal and Steel Commission in the past ten years for the coal and steel industry and now adopted by the International Ergonomics Association. Otherwise prevention of occupational hazards would be reduced to early diagnosis only, relinquishing all prospects of primary prevention which, if correctly applied, can only be achieved via an anthropocentric design concept. Therefore new epistemological choices, new theories, methods and design procedures need to be widely implemented so that they can be correctly synthetized, in accordance with the centrality, the values and the aspirations of the human operator in complex systems.