Is cannabis use a significant exposition to nicotine?

Purpose: Young cannabis users are at increased risk for cigarette initiation and later progression to nicotine dependence. The present study assesses to which extent cannabis users are exposed to nicotine through mulling, a widespread process consisting of mixing tobacco to cannabis for its consumption. Methods: Data are issued from an ongoing observational study taking place in Switzerland. A total of 267 eligible participants (mean age 19 years, 46.4% males) completed an anonymous self-administered questionnaire on their tobacco and cannabis intake in the previous 5 days. They also provided a urine sample that was blindly analyzed for cotinine (a key metabolite of nicotine) using liquid-chromatography coupled mass-spectrometry. After the exclusion of cannabis users not having smoked at least one joint/blunt in which tobacco had been mixed (n _ 2), and participants reporting other sources of nicotine exposition than cigarettes or mulling (n _37), four groups were created: cannabis and cigarette abstainers (ABS, n_ 69), cannabis only smokers (CAS; n _ 33), cigarette only smokers (CIS; n _ 62); and cannabis and cigarette smokers (CCS, n _ 64). Cotinine measures of CAS were compared to those of ABS, CIS and CCS. All comparisons were performed using ANCOVA, controlling for age, gender, ethnicity, BMI and environmental exposure to cigarette smoke in the past month (at home, in school/at work, in social settings). The number of mixed joints/blunts smoked in the previous 5 days was additionally taken into account when comparing CAS to CCS. Cotinine values (ng/ml) are reported as means with 95% confidence interval (95% CI). Results: In the previous 5 days, CAS had smoked on average 10 mixed joints/blunts, CIS 30 cigarettes, and CCS 8 mixed joints/ blunts and 41 cigarettes. Cotinine levels of participants considerably differed between groups. The lowest measure was found among ABS (3.2 [0.5-5.9]), followed in growing order by CAS (294.6 [157.1-432.0]), CIS (362.8 [258.4-467.3]), and CCS (649.9 [500.7-799.2]). In the multivariate analysis, cotinine levels of CAS were significantly higher than those of ABS (p _.001), lower than those of CCS (p _ .003), but did not differ from levels of CIS (p _ .384). Conclusions: Our study reveals cannabis users to be significantly exposed to nicotine through mulling, even after controlling for several possible confounders such as environmental exposure to cigarette smoke. Utmost, mixing tobacco to Poster cannabis can result in a substantial nicotine exposition as cotinine levels from cannabis only smokers were as high as those of moderate cigarette smokers. Our findings also suggest that mulling is adding up to the already important nicotine exposition of cigarettes smokers. Because of the addictiveness of nicotine, mulling should be part of a comprehensive assessment of substance use among adolescents and young adults, especially when supporting their cannabis and cigarette quitting attempts. Sources of Support: This study was funded by the Public Health Service of the Canton de Vaud. Dr. BÊlanger's contribution was possible through grants from the Royal College of Physicians and Surgeons of Canada, the CHUQ/CMDP Foundation and the Laval University McLaughlin program, QuÊbec, Canada.

Bilateral extraperitoneal uterosacral vaginal vault suspension: a 2-year follow-up longitudinal case series of 123 patients.

INTRODUCTION AND HYPOTHESIS: The objective of this study is to assess anatomical and functional results of the extraperitoneal uterosacral ligament suspension (USL) in women with post-hysterectomy vaginal vault prolapse. METHODS: One hundred and twenty-three consecutive women were included. Concurrent procedures were anterior colporraphy with fascial repair (20%) and mesh reinforcement (49%), posterior colporraphy with fascial repair (38%) and mesh reinforcement (56%) and a sling procedure (29%). Women were assessed using Baden and Walker and pelvic organ prolapse quantification classification pre- and post-operatively. RESULTS: One hundred and ten patients (89%) were available for follow-up. Mean follow-up was 2 years. Objective success rate regarding the vaginal cuff is 95.4%. Global anatomical success rate was 85.5%. Urinary, coital and bowel symptoms were improved following surgery. Mesh exposure rate was 19.3%, with all cases managed conservatively or with minor interventions. CONCLUSION: Bilateral extraperitoneal USL is an effective operation to restore apical support with low morbidity, which avoids potential risks associated with opening the peritoneal cavity.

In vitro evaluation of staphylococcus aureus biofilm formation on bone grafts and bone substitues

Background: Bacteria form a biofilm on the surface of orthopaedic devices, causing persistent and infection. Little is known about biofilms formation on bone grafts and bone substitutes. We analyzed various representative materials regarding their propensity for biofilm formation caused by Staphylococcus aureus.Methods: As bone graft beta-tricalciumphosphate (b-TCP, CyclOsTM) and as bone substitute a tantalum metal mesh (trabecular metalTM) and PMMA (Pala-cosTM) were investigated. As test organism S. aureus (strain ATCC 29213) was used. Test materials were incubated with bacterial solution of 105 colony-forming units (cfu)/ml at 37°C for 24 h without shaking. After 24 h, the test materials were removed and washed 3 times in normal saline, followed by sonication in 50 ml Ringer solution at 40 kHz for 5 minutes. The resulting sonication fluid was plated in aliquots of 0.1 ml onto aerobe blood agar with 5% sheep blood and incubated at 37°C with 5% CO2 for 24 h. Then, bacterial counts were enumerated and expressed as cfu/ml. All experiments were performed in triplicate to calculate the mean ± standard deviation. The Wilcoxon test was used for statistical calculations.Results: The three investigated materials show a differing specific surface with b-TCB>trabecular metal>PMMA per mm2. S. aureus formed biofilm on all test materials as confirmed by quantitative culture after washing and sonication. The bacterial counts in sonication fluid (in cfu/ml) were higher in b-TCP (5.1 x 106 ± 0.6 x 106) and trabecular metal (3.7 x 106 ± 0.6 x 106) than in PMMA (3.9 x 104 ± 1.8 x 104), p<0.05.Conclusion: Our results demonstrate that about 100-times more bacteria adhere on b-TCP and trabecular metal than on PMMA, reflecting the larger surface of b-TCP and trabecuar metal compared to the one of PMMA. This in-vitro data indicates that bone grafts are susceptible to infection. Further studies are needed to evaluate efficient approaches to prevent and treat infections associated with bone grafts and substitutes, including modification of the surface or antibacterial coating.

A tailored approach for the treatment of indirect inguinal hernia in adults--an old problem revisited.

A patent processus vaginalis peritonei (PPV) presents typically as an indirect hernia with an intact inguinal canal floor during childhood. Little is known however about PPV in adults and its best treatment. A cohort study included all consecutive patients admitted for ambulatory open hernia repair. In patients with a PPV, demographics, hernia characteristics, and outcome were prospectively assessed. Annulorrhaphy was the treatment of choice in patients with an internal inguinal ring diameter of < 30 mm. Between 1998 and 2006, 92 PPVs (two bilateral) were diagnosed in 676 open hernia repairs (incidence of 14%). Eighty nine of the 90 patients were males, the median age was 34 years (range: 17-85). A PPV was right-sided in 67% and partially obliterated in 66%. Forty-one patients had an annulorrhaphy and 51 patients had a tension-free mesh repair. The median operation time was significantly shorter in the annulorrhaphy group (38 vs. 48 min, P <.0001). In a median follow-up period of 56 months (27-128), both groups did not differ concerning recurrence (1/41 vs. 2/51), chronic pain (3/41 vs. 4/51), and hypoesthesia (5/41 vs. 9/51). There was however a clear trend to less neuropathic symptoms in favor of annulorrhaphy (0/41 vs. 5/51, P < 0.066). PPV occurs in 14% of adults undergoing hernia repair. In selected patients, annulorrhaphy takes less time and is associated with equally low recurrence but less potential for neuropathic symptoms.

Physiological traits affecting the distribution and wintering strategy of the bat Tadarida teniotis

The ability to enter torpor at low ambient temperature, which enables insectivorous bats to survive seasonal food shortage, is often seen as a prerequisite for colonizing cold environments. Free-tailed bats (Molossidae) show a distribution with a maximum latitudinal extension that appears to be intermediate between truly tropical and temperate-zone bat families. We therefore tested the hypothesis that Tadarida teniotis, the molossid species reaching the highest latitude worldwide (46 degrees N), lacks the extreme physiological adaptations to cold that enable other sympatric bats to enter further into the temperate zone. We studied the metabolism of individuals subjected to various ambient temperatures in the laboratory by respirometry, and we monitored the body temperature of free-ranging individuals in winter and early spring in the Swiss Alps using temperature-sensitive radio-tags. For comparison, metabolic data were obtained from Nyctalus noctula, a typically hibernating vespertilionid bat of similar body size and convergent foraging tactics. The metabolic data support the hypothesis that T. teniotis cannot experience such low ambient temperatures as sympatric temperate-zone vespertilionid bats without incurring much higher energetic costs for thermogenesis. The minimum rate of metabolism in torpor was obtained at 7.5 degrees-10 degrees C in T. teniotis, as compared to 2.5 degrees-5 degrees C in N. noctula. Field data showed that T. teniotis behaves as a classic thermo-conforming hibernator in the Alps, with torpor bouts lasting up to 8 d. This contradicts the widely accepted opinion that Molossidae are nonhibernating bars. However, average body temperature (10 degrees-13 degrees C) and mean arousal frequency (3.4 d in one bat in January) appear to be markedly higher than in other temperate-zone bat species. At the northern border of its range T. teniotis selects relatively warm roosts (crevices in tall, south-exposed limestone cliffs) in winter where temperatures oscillate around 10 degrees C. By this means, T. teniotis apparently avoids the risk of prolonged exposure to energetically critical ambient temperatures in torpor (<6.5 degrees-7.5 degrees C) during cold spells. Possibly shared by other Molossidae, the physiological pattern observed in T. teniotis may clearly be linked to the intermediate latitudinal extension of this bat family.

Spatial planning to the test of property rights in Switzerland : an innovative land management approach to coordinate spatial planning goals with property rights interests

In Switzerland, the land management regime is characterized by a liberal attitude towards the institution of property rights, which is guaranteed by the Constitution. Under the present Swiss constitutional arrangement, authorities (municipalities) are required to take into account landowners' interests when implementing their spatial planning policy. In other words, the institution of property rights cannot be restricted easily in order to implement zoning plans and planning projects. This situation causes many problems. One of them is the gap between the way land is really used by the landowners and the way land should be used based on zoning plans. In fact, zoning plans only describe how landowners should use their property. There is no sufficient provision for handling cases where the use is not in accordance with zoning plans. In particular, landowners may not be expropriated for a non-conforming use of the land. This situation often leads to the opening of new building areas in greenfields and urban sprawl, which is in contradiction with the goals set into the Federal Law on Spatial Planning. In order to identify legal strategies of intervention to solve the problem, our paper is structured into three main parts. Firstly, we make a short description of the Swiss land management regime. Then, we focus on an innovative land management approach designed to implement zoning plans in accordance with property rights. Finally, we present a case study that shows the usefulness of the presented land management approach in practice. We develop three main results. Firstly, the land management approach brings a mechanism to involve landowners in planning projects. Coordination principle between spatial planning goals and landowners' interests is the cornerstone of all the process. Secondly, the land use is improved both in terms of space and time. Finally, the institution of property rights is not challenged, since there is no expropriation and the market stays free.

Procedure for human saphenous veins ex vivo perfusion and external reinforcement.

The mainstay of contemporary therapies for extensive occlusive arterial disease is venous bypass graft. However, its durability is threatened by intimal hyperplasia (IH) that eventually leads to vessel occlusion and graft failure. Mechanical forces, particularly low shear stress and high wall tension, are thought to initiate and to sustain these cellular and molecular changes, but their exact contribution remains to be unraveled. To selectively evaluate the role of pressure and shear stress on the biology of IH, an ex vivo perfusion system (EVPS) was created to perfuse segments of human saphenous veins under arterial regimen (high shear stress and high pressure). Further technical innovations allowed the simultaneous perfusion of two segments from the same vein, one reinforced with an external mesh. Veins were harvested using a no-touch technique and immediately transferred to the laboratory for assembly in the EVPS. One segment of the freshly isolated vein was not perfused (control, day 0). The two others segments were perfused for up to 7 days, one being completely sheltered with a 4 mm (diameter) external mesh. The pressure, flow velocity, and pulse rate were continuously monitored and adjusted to mimic the hemodynamic conditions prevailing in the femoral artery. Upon completion of the perfusion, veins were dismounted and used for histological and molecular analysis. Under ex vivo conditions, high pressure perfusion (arterial, mean = 100 mm Hg) is sufficient to generate IH and remodeling of human veins. These alterations are reduced in the presence of an external polyester mesh.

A multilevel multiscale finite volume method

The Multiscale Finite Volume (MsFV) method has been developed to efficiently solve reservoir-scale problems while conserving fine-scale details. The method employs two grid levels: a fine grid and a coarse grid. The latter is used to calculate a coarse solution to the original problem, which is interpolated to the fine mesh. The coarse system is constructed from the fine-scale problem using restriction and prolongation operators that are obtained by introducing appropriate localization assumptions. Through a successive reconstruction step, the MsFV method is able to provide an approximate, but fully conservative fine-scale velocity field. For very large problems (e.g. one billion cell model), a two-level algorithm can remain computational expensive. Depending on the upscaling factor, the computational expense comes either from the costs associated with the solution of the coarse problem or from the construction of the local interpolators (basis functions). To ensure numerical efficiency in the former case, the MsFV concept can be reapplied to the coarse problem, leading to a new, coarser level of discretization. One challenge in the use of a multilevel MsFV technique is to find an efficient reconstruction step to obtain a conservative fine-scale velocity field. In this work, we introduce a three-level Multiscale Finite Volume method (MlMsFV) and give a detailed description of the reconstruction step. Complexity analyses of the original MsFV method and the new MlMsFV method are discussed, and their performances in terms of accuracy and efficiency are compared.

Clinal variation in a brown lemur (Eulemur spp.) hybrid zone: Combining morphological, genetic and climatic data to examine stability.

Studies of hybrid zones can inform our understanding of reproductive isolation and speciation. Two species of brown lemur (Eulemur rufifrons and E. cinereiceps) form an apparently stable hybrid zone in the Andringitra region of south-eastern Madagascar. The aim of this study was to identify factors that contribute to this stability. We sampled animals at 11 sites along a 90-km transect through the hybrid zone and examined variation in 26 microsatellites, the D-loop region of mitochondrial DNA, six pelage and nine morphological traits; we also included samples collected in more distant allopatric sites. Clines in these traits were noncoincident, and there was no increase in either inbreeding coefficients or linkage disequilibrium at the centre of the zone. These results could suggest that the hybrid zone is maintained by weak selection against hybrids, conforming to either the tension zone or geographical selection-gradient model. However, a closer examination of clines in pelage and microsatellites indicates that these clines are not sigmoid or stepped in shape but instead plateau at their centre. Sites within the hybrid zone also occur in a distinct habitat, characterized by greater seasonality in precipitation and lower seasonality in temperature. Together, these findings suggest that the hybrid zone may follow the bounded superiority model, with exogenous selection favouring hybrids within the transitional zone. These findings are noteworthy, as examples supporting the bounded superiority model are rare and may indicate a process of ecologically driven speciation without geographical isolation.

Rockfall characterisation and structural protection: A review

Rockfall is an extremely rapid process involving long travel distances. Due to these features, when an event occurs, the ability to take evasive action is practically zero and, thus, the risk of injury or loss of life is high. Damage to buildings and infrastructure is quite likely. In many cases, therefore, suitable protection measures are necessary. This contribution provides an overview of previous and current research on the main topics related to rockfall. It covers the onset of rockfall and runout modelling approaches, as well as hazard zoning and protection measures. It is the aim of this article to provide an in-depth knowledge base for researchers and practitioners involved in projects dealing with the rockfall protection of infrastructures, who may work in the fields of civil or environmental engineering, risk and safety, the earth and natural sciences.

The economic burden of alcohol dependence in europe.

AIMS: To determine the economic burden pertaining to alcohol dependence in Europe. METHODS: Database searching was combined with grey literature searching to identify costs and resource use in Europe relating to alcohol dependence as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) or the World Health Organisation's International Classification of Diseases (ICD-10). Searches combined MeSH headings for both economic terms and terms pertaining to alcohol dependence. Relevant outcomes included direct healthcare costs and indirect societal costs. Main resource use outcomes included hospitalization and drug costs. RESULTS: Compared with the number of studies of the burden of alcohol use disorders in general, relatively few focussed specifically on alcohol dependence. Twenty-two studies of variable quality were eligible for inclusion. The direct costs of alcohol dependence in Europe were substantial, the treatment costs for a single alcohol-dependent patient lying within the range euro1591-euro7702 per hospitalization and the annual total direct costs accounting for 0.04-0.31% of an individual country's gross domestic product (GDP). These costs were driven primarily by hospitalization; in contrast, the annual drug costs for alcohol dependence were low. The indirect costs were more substantial than the direct costs, accounting for up to 0.64% of GDP per country annually. Alcohol dependence may be more costly in terms of health costs per patient than alcohol abuse. CONCLUSIONS: This review confirms that alcohol dependence represents a significant burden for European healthcare systems and society. Difficulties in comparing across cost-of-illness studies in this disease area, however, prevent specific estimation of the economic burden.

Organisation and role of actin microfilaments during cellular growth and morphogenesis in the moss Physcomitrella patens

ABSTRACT The network of actin cytoskeleton is composed of actin filaments (F-actin) that are made by polymerisation of actin monomers and actin binding proteins. It is required for growth and morphogenesis of eukaryotic cells. The labelling of F-actin with constitutively expressed GFP-Talin (Kost et al., 1998) reveals the organisation of cellular actin networks in plants. Due to the lack of information on actin cytoskeleton through gametophytic development of the model moss plant Physcornitrella patens, stable transgenic lines overexpressing GFP-Talin were generated to detect F-actin structures. It is shown that the 35S promoter driven expression is not suitable for F-actin labelling in all cells. When it is replaced by the inducible heat-shock promoter Gmhsp17.3 from soybean, one hour mild heat stress at 37°C followed by recovery at 25°C is enough to induce efficient and transient labelling in all tissues without altering cellular morphology. The optimal observations of F-actin structures at different stages of moss development can be done between 12-18 hours after the induction. By using confocal microscopy, we demonstrate that stellated actin arrays were densely accumulated at the growing tip in regenerating protoplasts, apical protonemal cells and rhizoids and connected with a fine dispersed F-actin mesh. Following three-dimensional growth, the cortical star-like structures are widespread in the meristematic cells of developing bud and young gametophores. On the contrary, undulating networks of actin cables are found at the final stage of cell differentiation. During redifferentiation of mature leaf cells into protonemal filaments the rather stagnant web of actin cables is replaced by diffuse actin meshwork. In eukaryotes, nucleation of the actin monomers prior to their polymerization is driven by the seven-subunit ARP2/3 complex and formins. We cloned the gene encoding the ARP3 subunit of P. patens and generated arp3 mutants of the moss through gene disruption. The knockout of ARP3 affects the elongation of chloronemal cells and blocks further differentiation of caulonemal cells and rhizoids, and the gametophores are slightly stunted compared to wild-type. The arp mutants were created in the heat-shock inducible GFP-Talin strains allowing us to visualise a disorganised actin network and a lack of star-like actin cytoskeleton arrays. We conclude that ARP2/3 dependent nucleation of actin filaments is critical for the growth of filamentous cells, which in turn influences moss colonization. In complementation assays, the overexpression of Physcomitrella and Arab idopsis ARP3 genes in the moss arp3 mutant results in full recovery of wild type phenotype. In contrast the ARP3 subunit of fission yeast is not able to complement the moss arp3 mutant of moss indicating that regulation of the ARP2/3 dependent actin nucleation diverged in different kingdoms. RESUME Le réseau d'actine est composé de filaments de F-actine et d'un ensemble de protéines s'y attachant (Actin binding proteins). Le réseau d'actine est nécessaire à la croissance et à la morphogenèse de toutes les cellules eucaryotes. Chez les plantes, le marquage ainsi que l'étude de l'organisation du réseau d'actine ont été réalisés en utilisant une fusion GFP-Talin (Kost et al., 1998) exprimée sous le control d'un promoteur constitutif. Afin d'étudier les structures F-actine dans les cellules de Physcomitrella Patens et pour combler le manque d'information sur le développement des gamétophores, des lignées transgéniques stables surexprimant GFP-Talin ont été crées. Nous avons démontré que l'utilisation du promoteur 35S est inadéquate pour le marquage complet et homogène des filaments d'actine dans toutes les cellules de P. patens. Par contre, l'utilisation du promoteur inductible Gmhsp17.3 nous a permis de réaliser un marquage transitoire et général dans tous les tissus de la mousse. Une heure de choc thermique à 37°C suivis d'un temps de récupération de 12-18h à 25°C sont les conditions optimales (sans dommages cellulaires) pour l'observation des structures F-actine à différentes étapes de développement de la mousse. En utilisant la microscopie confocale, nous avons observé l'existence de structures F-actine accumulées en forme d'étoiles. Ces structures, qui sont liées au réseau de microfilaments d'actine, ont été observées dans les protoplastes en régénération, les cellules des protonema apicales ainsi que dans les rhizoïdes. En suivant la croissance tridimensionnelle, ces structures en étoiles ont été observées dans les cellules meristématiques des bourgeons et des jeunes gamétophores. Par contre, dans les cellules différentiées ces structures laissent place à des réseaux de câbles épais. Nous avons également remarqué que durant la redifferentiation des cellules foliaires le réseau de câbles de F-actine est remplacé par un réseau de F-actine diffus. Dans les cellules eucaryotes, la nucléation des filaments d'actirie précédant leur polymérisation est contrôlé par sept sous unités du complexe ARP2/3 et par des formines. Nous avons isolé le gène codant pour la sous unité ARP3 de P. patens et nous avons crée des mutants arp3 par intégration ciblée (Knockout). L'élongation des cellules chloronema est clairement affectée dans les mutants arp3. La différentiation des caulonemata et des rhizoïdes est bloquée et les gametophores sont légèrement plus courts comparé au type sauvage. A fin d'étudier l'organisation des filaments d'actines dans les mutants arp3, nous avons aussi réalisé un arp3-knockout dans la lignée Hsp-GFP-Talin. La nouvelle lignée générée nous a permis de visualiser une désorganisation du réseau d'actine et une absence complète de structures de F-actine accumulée en forme d'étoiles. Les résultats obtenus nous amènent à conclure que la nucléation (ARP2/3 dépendante) des filaments d'actine est indispensable à la croissance des cellules filamenteuses. Par conséquent, les filaments d'actine semblent avoir un rôle dans la colonisation des milieux par les mousses. Nous avons également procédé à des essais de complémentation du mutant arp3. La surexpression des gènes ARP3 de Physcomitrella et d'Arabidopsis dans les cellules du mutant arp3 rétabli complètement le phénotype WT. Par contre, le gène ARP3 des levures n'est pas suffisant pour complémenter la même mutation dans les cellules de mousses. Ce résultat démontre que les mécanismes de régulation de la nucléation des filaments d'actine (ARP2/3 dépendante) sont différents entre les différents groupes d'eucaryotes.

Algies après cure de hernie inguinale: que faire [Pain after inguinal hernia repair: what to do?]

Hernia repair one of the most frequently performed operations in general surgery. With the introduction of tension-free mesh repair, recurrence rates dropped well below 5% for open and laparoscopic procedures. However, chronic postoperative pain remains a widely neglected complication with a high socio-economic impact. It occurs in about 10-20% of patients after hernia repair. We review the different types of post-herniorrhaphy pain with the typical diagnostic features and we conclude with a pragmatic algorithm based on our clinical experience.

Constraining 3-D electrical resistance tomography with GPR reflection data forimproved aquifer characterization

Surface-based ground penetrating radar (GPR) and electrical resistance tomography (ERT) are common tools for aquifer characterization, because both methods provide data that are sensitive to hydrogeologically relevant quantities. To retrieve bulk subsurface properties at high resolution, we suggest incorporating structural information derived from GPR reflection data when inverting surface ERT data. This reduces resolution limitations, which might hinder quantitative interpretations. Surface-based GPR reflection and ERT data have been recorded on an exposed gravel bar within a restored section of a previously channelized river in northeastern Switzerland to characterize an underlying gravel aquifer. The GPR reflection data acquired over an area of 240×40 m map the aquifer's thickness and two internal sub-horizontal regions with different depositional patterns. The interface between these two regions and the boundary of the aquifer with then underlying clay are incorporated in an unstructured ERT mesh. Subsequent inversions are performed without applying smoothness constraints across these boundaries. Inversion models obtained by using these structural constraints contain subtle resistivity variations within the aquifer that are hardly visible in standard inversion models as a result of strong vertical smearing in the latter. In the upper aquifer region, with high GPR coherency and horizontal layering, the resistivity is moderately high (N300 Ωm). We suggest that this region consists of sediments that were rearranged during more than a century of channelized flow. In the lower low coherency region, the GPR image reveals fluvial features (e.g., foresets) and generally more heterogeneous deposits. In this region, the resistivity is lower (~200 Ωm), which we attribute to increased amounts of fines in some of the well-sorted fluvial deposits. We also find elongated conductive anomalies that correspond to the location of river embankments that were removed in 2002.

A numeric model to simulate solar individual ultraviolet exposure.

Exposure to solar ultraviolet (UV) light is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors. Individual exposure data remain scarce and development of alternative assessment methods is greatly needed. We developed a model simulating human exposure to solar UV. The model predicts the dose and distribution of UV exposure received on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a rendering engine that estimates the solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by each triangle was calculated, taking into account reflected, direct and diffuse radiation, and shading from other body parts. Dosimetric measurements (n = 54) were conducted in field conditions using a foam manikin as surrogate for an exposed individual. Dosimetric results were compared to the model predictions. The model predicted exposure to solar UV adequately. The symmetric mean absolute percentage error was 13%. Half of the predictions were within 17% range of the measurements. This model provides a tool to assess outdoor occupational and recreational UV exposures, without necessitating time-consuming individual dosimetry, with numerous potential uses in skin cancer prevention and research.