The genetic history of Scandinavia from the Roman Iron Age to the present.

We investigate a 2,000-year genetic transect through Scandinavia spanning the Iron Age to the present, based on 48 new and 249 published ancient genomes and genotypes from 16,638 modern individuals. We find regional variation in the timing and magnitude of gene flow from three sources: the eastern Baltic, the British-Irish Isles, and southern Europe. British-Irish ancestry was widespread in Scandinavia from the Viking period, whereas eastern Baltic ancestry is more localized to Gotland and central Sweden. In some regions, a drop in current levels of external ancestry suggests that ancient immigrants contributed proportionately less to the modern Scandinavian gene pool than indicated by the ancestry of genomes from the Viking and Medieval periods. Finally, we show that a north-south genetic cline that characterizes modern Scandinavians is mainly due to the differential levels of Uralic ancestry and that this cline existed in the Viking Age and possibly earlier.

Travel behaviour change in old age: the role of critical incidents in public transport.

Older people's travel behaviour is affected by negative or positive critical incidents in the public transport environment. With the objective of identifying such incidents during whole trips and examining how travel behaviour had changed, we have conducted in-depth interviews with 30 participants aged 65-91 years in the County of Stockholm, Sweden. Out of 469 incidents identified, 77 were reported to have resulted in travel behaviour change, 67 of them in a negative way. Most critical incidents were encountered in the physical environment on-board vehicles and at stations/stops as well as in pricing/ticketing. The findings show that more personal assistance, better driving behaviour, and swift maintenance of elevators and escalators are key facilitators that would improve predictability in travelling and enhance vulnerable older travellers' feeling of security. The results demonstrate the benefit of involving different groups of end users in future planning and design, such that transport systems would meet the various needs of its end users.

Overall accessibility to traveling by rail for the elderly with and without functional limitations: the whole-trip perspective.

Elderly persons' perceived accessibility to railway traveling depends on their functional limitations/diseases, their functional abilities and their travel behaviors in interaction with the barriers encountered during whole trips. A survey was conducted on a random sample of 1000 city residents (65-85 years old; 57% response rate). The travels were perceived least accessible by respondents with severely reduced functional ability and by those with more than one functional limitation/disease (e.g., restricted mobility and chronic pain). Those who traveled "often", perceived the accessibility to be better than those who traveled less frequently. For travelers with high functional ability, the main barriers to more frequent traveling were travel costs and low punctuality. For those with low functional ability, one's own health was reported to be the main barrier. Our results clarify the links among existing functional limitations/functional abilities, the barriers encountered, the travel behavior, and the overall accessibility to traveling. By operationalizing the whole-trip concept as a chain of events, we deliver practical knowledge on vulnerable groups for decision-making to improve the transport environment for all.

Feeling small: exploring the tactile perception limits.

The human finger is exquisitely sensitive in perceiving different materials, but the question remains as to what length scales are capable of being distinguished in active touch. We combine material science with psychophysics to manufacture and haptically explore a series of topographically patterned surfaces of controlled wavelength, but identical chemistry. Strain-induced surface wrinkling and subsequent templating produced 16 surfaces with wrinkle wavelengths ranging from 300 nm to 90 µm and amplitudes between 7 nm and 4.5 µm. Perceived similarities of these surfaces (and two blanks) were pairwise scaled by participants, and interdistances among all stimuli were determined by individual differences scaling (INDSCAL). The tactile space thus generated and its two perceptual dimensions were directly linked to surface physical properties - the finger friction coefficient and the wrinkle wavelength. Finally, the lowest amplitude of the wrinkles so distinguished was approximately 10 nm, demonstrating that human tactile discrimination extends to the nanoscale.

Perceptual constancy in auditory perception of distance to railway tracks.

Distance to a sound source can be accurately estimated solely from auditory information. With a sound source such as a train that is passing by at a relatively large distance, the most important auditory information for the listener for estimating its distance consists of the intensity of the sound, spectral changes in the sound caused by air absorption, and the motion-induced rate of change of intensity. However, these cues are relative because prior information/experience of the sound source-its source power, its spectrum and the typical speed at which it moves-is required for such distance estimates. This paper describes two listening experiments that allow investigation of further prior contextual information taken into account by listeners-viz., whether they are indoors or outdoors. Asked to estimate the distance to the track of a railway, it is shown that listeners assessing sounds heard inside the dwelling based their distance estimates on the expected train passby sound level outdoors rather than on the passby sound level actually experienced indoors. This form of perceptual constancy may have consequences for the assessment of annoyance caused by railway noise.

The role of odour quality in the perception of binary and higher-order mixtures.

Twenty participants scaled similarities in odour quality, odour intensity and pleasantness/ unpleasantness of 10 binary and 5 higher-order mixtures of 5 odorous degradation products from the polymer Polyamide 6.6. The perceived odour qualities of all binary mixtures were represented well as intermediary vectors relative to their component-odour vectors in a three-component principal components analysis. The odour qualities of the "floral/fruity" 2-pentylcyclopentan-1-one and the "sharp/cheese-like" pentanoic acid contributed profoundly to their binary mixtures, as did the "minty" cyclopentanone, but in fewer cases. Conversely, the "ether-like" 2-methyl pyridine and "nutty" butanamide did not contribute much. Odour similarity was shown to be caused by odour quality, rather than odour intensity. Three out of five degradation products formed distinct clusters of odours and were therefore interpreted to be profound contributors to the odour quality of the binary mixtures. The higher-order mixtures created new odour qualities which were completely different and untraceable to their various parts as perceived alone. These results demonstrate that it is critical to research the perception of natural mixtures in order to be able to understand the human olfactory code.

A principal components model of soundscape perception.

There is a need for a model that identifies underlying dimensions of soundscape perception, and which may guide measurement and improvement of soundscape quality. With the purpose to develop such a model, a listening experiment was conducted. One hundred listeners measured 50 excerpts of binaural recordings of urban outdoor soundscapes on 116 attribute scales. The average attribute scale values were subjected to principal components analysis, resulting in three components: Pleasantness, eventfulness, and familiarity, explaining 50, 18 and 6% of the total variance, respectively. The principal-component scores were correlated with physical soundscape properties, including categories of dominant sounds and acoustic variables. Soundscape excerpts dominated by technological sounds were found to be unpleasant, whereas soundscape excerpts dominated by natural sounds were pleasant, and soundscape excerpts dominated by human sounds were eventful. These relationships remained after controlling for the overall soundscape loudness (Zwicker's N(10)), which shows that 'informational' properties are substantial contributors to the perception of soundscape. The proposed principal components model provides a framework for future soundscape research and practice. In particular, it suggests which basic dimensions are necessary to measure, how to measure them by a defined set of attribute scales, and how to promote high-quality soundscapes.

A model for the perception of environmental sound based on notice-events.

An approach is proposed to shed light on the mechanisms underlying human perception of environmental sound that intrudes in everyday living. Most research on exposure-effect relationships aims at relating overall effects to overall exposure indicators in an epidemiological fashion, without including available knowledge on the possible underlying mechanisms. Here, it is proposed to start from available knowledge on audition and perception to construct a computational framework for the effect of environmental sound on individuals. Obviously, at the individual level additional mechanisms (inter-sensory, attentional, cognitive, emotional) play a role in the perception of environmental sound. As a first step, current knowledge is made explicit by building a model mimicking some aspects of human auditory perception. This model is grounded in the hypothesis that long-term perception of environmental sound is determined primarily by short notice-events. The applicability of the notice-event model is illustrated by simulating a synthetic population exposed to typical Flemish environmental noise. From these simulation results, it is demonstrated that the notice-event model is able to mimic the differences between the annoyance caused by road traffic noise exposure and railway traffic noise exposure that are also observed empirically in other studies and thus could provide an explanation for these differences.

Children's annoyance reactions to aircraft and road traffic noise.

Since annoyance reactions of children to environmental noise have rarely been investigated, no source specific exposure-response relations are available. The aim of this paper is to investigate children's reactions to aircraft and road traffic noise and to derive exposure-response relations. To this end, children's annoyance reactions to aircraft and road traffic noise in both the home and the school setting were investigated using the data gathered in a cross-sectional multicenter study, carried out among 2844 children (age 9-11 years) attending 89 primary schools around three European airports. An exposure-response relation was demonstrated between exposure to aircraft noise at school (L(Aeq,7-23 h)) and severe annoyance in children: after adjustment for confounders, the percentage severely annoyed children was predicted to increase from about 5.1% at 50 dB to about 12.1% at 60 dB. The findings were consistent across the three samples. Aircraft noise at home (L(Aeq,7-23 h)) demonstrated a similar relation with severe annoyance. Children attending schools with higher road traffic noise (L(Aeq,7-23 h)) were more annoyed. Although children were less annoyed at levels above 55 dB, the shapes of the exposure-response relations found among children were comparable to those found in their parents.

Noise annoyance and activity disturbance before and after the erection of a roadside noise barrier.

Questionnaire studies were conducted in a residential area before and after the erection of a 2.25 m high noise barrier of conventional type along a heavily traveled road (19,600 vehicles/24 h). The interval between studies was two years. Houses closest to the barrier received a sound-level reduction from -70.0 to 62.5 dB Lden at the most exposed facade. The sound-level reduction decreased with distance to the road, and was negligible for houses at more than 100 m distance. Up to this distance, the noise barrier reduced residents' noise annoyance outdoors and indoors as well as improved speech communication outdoors. Indoors, speech communication and sleep disturbance were slightly but nonsignificantly improved. Predictions of the number of annoyed persons from published exposure-response curves (in Lden) agreed with the percentage of residents being annoyed when indoors, before and after the barrier. Conversely, the percentage of residents being annoyed when outdoors clearly exceeded the predictions. These results suggest that these exposure-response curves may be used in predicting indoor situations, but they should not be applied in situations where outdoor annoyance is at focus.

Transport of methylmercury and inorganic mercury to the fetus and breast-fed infant.

It is well established that methylmercury (MeHg) and mercury vapor pass the placenta, but little is known about infant exposure via breast milk. We measured MeHg and inorganic mercury (I-Hg) in blood of Swedish mothers (n = 20) and their infants, as well as total mercury (T-Hg) in breast milk up to 13 weeks postpartum. Infant blood MeHg was highly associated with maternal blood MeHg at delivery, although more than twice as high. Infant MeHg decreased markedly until 13 weeks of age. Infant blood I-Hg was associated with, and about as high as, maternal blood I-Hg at delivery. Infant I-Hg decreased until 13 weeks. In breast milk, T-Hg decreased significantly from day 4 to 6 weeks after delivery but remained unchanged thereafter. At 13 weeks, T-Hg in breast milk was associated with infant MeHg but not with maternal MeHg. Conversely, T-Hg in breast milk was associated with maternal I-Hg but not with infant I-Hg. From the findings of the present study in which the exposure to both MeHg and I-Hg was low, we conclude that the exposure to both forms of mercury is higher before birth than during the breast-feeding period, and that MeHg seems to contribute more than I-Hg to infant exposure postnatally via breast milk.

Master scaling of perceived intensity of touch, cold and warmth.

A new approach is presented for scaling perceived intensity of touch, cold and warmth based on magnitude estimation. In this method named master scaling thenar is utilized as common reference area for scaling and calibrating perceived intensity. The master scaling is particularly well suited for clinical applications in which the stimulation in pain-affected body areas creates a complex perception (e.g., paradoxical heat for cold stimulation) and/or aberrant psychophysical functions for perceived intensity. The results from three different experiments showed that: (a) All patients and healthy subjects were able to scale adequately the perceived intensity of touch, cold, and warmth at unaffected body areas. (b) Thenar stimulations were shown to be adequate common references in the joint scaling of perceived intensity of other body areas in pain patients as well as healthy persons. (c) Individual thenar psychophysical functions can be used for screening patients and healthy persons with regard to their ability to scale perceived intensity of touch, cold and warmth. (d) Master scaled perceived intensity scales can be used for determining if various pain-unaffected body areas are normal or abnormal in patients and in healthy persons. (e) The interindividual variation in perceived intensity is considerably reduced after master scaling and approaches that of intraindividual variation as found in olfaction and hearing. Finally, empirically based thenar Master Functions of perceived intensity for touch, cold and warmth are proposed to be used in future sensory testing of patients, as well as of healthy persons.

Identification of sounds from traffic.

Listeners' ability to identify road-traffic, aircraft, or train sounds in environmental sound recordings was studied in a psychoacoustical experiment involving 16 participants. In free-labeling identification, excerpt traffic sounds were described in terms of "object" (sound-producing source) rather than in terms of perceptual attribute. The main sounds identified were traffic sounds, but a few references were also made to machine-related or water-related sources. Sounds from aircraft were easier to identify than the sounds from trains, which in turn were easier to identify than the sounds from road-traffic. This identification order was confirmed in multiple-choice and dominant-source identification tasks. Compared to free-labeling, multiple-choice identifications produced considerably more false alarms, i.e., identification of a sound source not present. For multiple-choice, several sound sources were particularly identified in the excerpt of road-traffic and train sounds although the (recorded) sound was typically clearly discerned in the joint dominant-source identification task. A comparison of the acoustic properties of the traffic sounds suggested that spectral rather than temporal cues were used in sound-source identification.

Quantitative and qualitative perceptual analysis of cold dysesthesia and hyperalgesia in fibromyalgia.

Somatosensory perception thresholds, perceived intensity, and quality of perceptions were assessed in 20 women with fibromyalgia syndrome (FMS) and in 20 healthy age-matched female controls. All patients and controls scaled perceived intensity and described perceived quality of randomized thermal (Thermotest) and tactile (von Frey filaments) stimulation. Perceived intensity was scaled by free-number magnitude estimation and interindividual comparability was accomplished by Master Scaling. Perceived quality was assessed by choosing verbal descriptors from a list. Thenar was used as a reference for each modality tested. All patients were able to reliably scale perceived intensity at thenar, as well as in pain-affected body areas. Perception thresholds for cold pain, heat pain, cold-pain tolerance and heat-pain tolerance were significantly lower in patients than controls. For cold and tactile stimulation, the master scaled perceived intensities were significantly higher in patients' pain-affected areas, whereas for warmth/heat stimulation, the intensities were significantly lower. In the qualitative perceptual analysis the most striking and significant finding was the aberration of cold-evoked perceptions in all patients: most stimuli in the range of 30-10 degrees C were reported as heat or other paresthetic or dysesthetic perceptions. The perceptual quality of warmth, and of touch, did not differ from the controls. Another aberration was observed in the nociceptive range of thermal and of tactile stimulation as significantly more frequent pain-related descriptors than in controls. This indicates a general nociceptive facilitation in addition to the lower thermal pain thresholds. The combination of cold hyperesthesia, cold dysesthesia, and multimodal hyperalgesia suggests a selective pathophysiology at a particular level of integration, possibly in the insular cortex. It is suggested that the aberrations revealed by the supraliminal sensory evaluation may be generic for FMS. Particularly, the aberrations established in all patients for perceived quality and intensity in the cold sensory channel may be an additional diagnostic criterion.

Guidelines for community noise

It presents information and guidance on noise sources and their measurement, adverse health effects of noise, guideline values, and noise management.