bluuebunny/crossref_metadata_2025 huggingface dataset:
Vegetation and climatec. 12 300–9000 cal. yr BP at Andøya, NW Norway
Authors: VORREN KARL‐DAG , ELVERLAND ELLEN , BLAAUW MAARTEN , RAVNA ERLING K. , JENSEN CHRISTIN A. H.
Published: February 2009

Owing to proximity of the North Atlantic Stream and the shelf, the Andøya biota are assumed to have responded rapidly to climatic changes taking place after the Weichselian glaciation. Palynological, macrofossil, loss‐on‐ignition, tephra and14C data from three sites at the northern part of the island of Andøya were studied. The period 12 300–11 950 cal. yr BP was characterized by polar desert vegetation, and 11 950–11 050 cal. yr BP by a moisture‐demanding predominantly low‐arcticOxyriavegetation. During the period 11 050–10 650 cal. yr BP, there was a climatic amelioration towards a sub‐arctic climate and heaths dominated byEmpetrum. After 10 650 cal. yr BP theOxyriavegetation disappeared. As early as about 10 800 cal. yr BP the bryozoanCristatella mucedoindicated a climate sufficient forBetulawoodland. However, tree birch did not establish until 10 420–10 250 cal. yr BP, indicating a time‐lag for the formation ofBetulaecotypes adapted to the oceanic climate of Andøya. From about 10 150 to 9400 cal. yr BP the summers were dry and warm. There was a change towards moister, though comparatively warm, climatic conditions about 9400 cal. yr BP. The present data are compared with evidence from marine sediments and the deglaciation history in the region. It is suggested that during most of the period 11 500–10 250 cal. yr BP a similar situation as in present southern Greenland existed, with birch woodland in the inner fjords near the ice sheet and low‐arctic heath vegetation along the outer coast.
PHYSIOLOGICAL RESPONSES OF ECKLONIA RADIATA (LAMINARIALES) TO A LATITUDINAL GRADIENT IN OCEAN TEMPERATURE1
Authors: Staehr Peter A. , Wernberg Thomas
Published: February 2009

We tested the ability of sporophytes of a small kelp, Ecklonia radiata (C. Agardh) J. Agardh, to adjust their photosynthesis, respiration, and cellular processes to increasingly warm ocean climates along a latitudinal gradient in ocean temperature (∼4°C). Tissue concentrations of pigment and nutrients decreased with increasing ocean temperature. Concurrently, a number of gradual changes in the metabolic balance of E. radiata took place along the latitudinal gradient. Warm‐acclimatized kelps had 50% lower photosynthetic rates and 90% lower respiration rates at the optimum temperature than did cool‐acclimatized kelps. A reduction in temperature sensitivity was also observed as a reduction in Q10‐values from cool‐ to warm‐acclimatized kelps for gross photosynthesis (Q10: 3.35 to 1.45) and respiration (Q10: 3.82 to 1.65). Respiration rates were more sensitive to increasing experimental temperatures (10% higher Q10‐values) than photosynthesis and had a higher optimum temperature, irrespective of sampling location. To maintain a positive carbon balance, E. radiata increased the critical light demand (Ec) exponentially with increasing experimental temperature. The temperature dependency of Ec was, however, weakened with increasing ocean temperature, such that the critical light demand was relaxed in kelp acclimated to higher ocean temperatures. Nevertheless, calculations of critical depth limits suggested that direct effects of future temperature increases are unlikely to be as strong as effects of reduced water clarity, another globally increasing problem in coastal areas.
USING A NONANALYTICAL APPROACH TO MODEL NONLINEAR DYNAMICS IN PHOTOSYNTHESIS AT THE PHOTOSYSTEM LEVEL1
Authors: Laney Samuel R. , Letelier Ricardo M. , Abbott Mark R.
Published: February 2009

Nonlinear dynamics in photon capture and uptake at the photosystem level may have a strong effect on photosynthetic yield. However, the magnitude of such effects is difficult to estimate theoretically because nonlinear systems often cannot be represented accurately using equations. A nonanalytical simulation was developed that used a simple decision tree and Monte Carlo methods, instead of equations, to model how a population of photosystems absorbs and utilizes photons from an ambient light field. This simulation replicated realistic kinetics in the closure and variable fluorescence yield of PSII on the single‐turnover timescale, as well as the saturating behavior in light‐driven electron flow that is observed in nature with increasing irradiance. This simulation indicated that the transfer of absorbed photon energy among PSII units can introduce strong nonlinear enhancement in light‐driven electron flow. However, this effect was seen only in populations with particular photosynthetic states as determined by physiological properties of PSII. Other populations with the same degree of energy transfer but with different photosynthetic states exhibited little enhancement in electron flow and, in some cases, a reduction. This nonanalytical approach provides a simple means to quantify theoretically how nonlinear dynamics in photosynthesis arise at the photosystem level and how these dynamics may act to enhance or constrain photosynthetic rates and yields. Such simulations can provide quantitative insight into different physiological bases of nonlinear light‐harvesting dynamics and identify those that would have the strongest theoretical influence and thus warrant closer experimental examination.
PHENOTYPIC PLASTICITY INDUCED IN TRANSPLANT EXPERIMENTS IN A MUTUALISTIC ASSOCIATION BETWEEN THE RED ALGA JANIA ADHAERENS (RHODOPHYTA, CORALLINALES) AND THE SPONGE HALICLONA CAERULEA (PORIFERA: HAPLOSCLERIDA): MORPHOLOGICAL RESPONSES OF THE ALGA1
Authors: Enríquez Susana , Ávila Enrique , Carballo José Luis
Published: February 2009

The association between the red macroalga Jania adhaerens J. V. Lamour. and the sponge Haliclona caerulea is the most successful life‐form between 2 and 4 m depth in Mazatlán Bay (Mexican Pacific). J. adhaerens colonizes the rocky intertidal area and penetrates into deeper areas only when it lives in association with H. caerulea. The aposymbiotic form of the sponge has not been reported in the bay. To understand the ecological success of this association, we examined the capacity of J. adhaerens to acclimate in Mazatlán Bay using transplant experiments. The transplanted aposymbiotic J. adhaerens did not survive the first 2 weeks; however, J. adhaerens when living in association with H. caerulea, acclimated easily to depth, showing no sign of mortality during the 103 d of the experiment. We conclude that the ability of J. adhaerens to colonize in deeper areas in this hydrodynamic environment may in part rely on the protection provided by the sponge to the algal canopy. Both species contribute to the shape of the associated form. Nevertheless, the morphological variation in the association appears to be dominated by the variation in J. adhaerens canopy to regulate pigment self‐shading under light‐limited conditions and/or tissue resistance under high hydrodynamics. Consequently, our results are consistent with light as the abiotic controlling factor, which regulates the lower depth distribution of the association in Mazatlán Bay, through limiting the growth rate of J. adhaerens. Hydrodynamics may determine the upper limit of the association by imposing high mass losses.
ENVIRONMENTAL MODULATION OF KARLOTOXIN LEVELS IN STRAINS OF THE COSMOPOLITAN DINOFLAGELLATE, KARLODINIUM VENEFICUM (DINOPHYCEAE)1
Authors: Adolf Jason E. , Bachvaroff Tsvetan R. , Place Allen R.
Published: February 2009

We examined the influence of N or P depletion, alternate N‐ or P‐sources, salinity, and temperature on karlotoxin (KmTx) production in strains of Karlodinium veneficum (D. Ballant.) J. Larsen, an ichthyotoxic dinoflagellate that shows a high degree of variability of toxicity in situ. The six strains examined represented KmTx 1 (CCMP 1974, MD 2) and KmTx 2 (CCMP 2064, CCMP 2283, MBM1) producers, and one strain that did not produce detectable karlotoxin under nutrient‐replete growth conditions (MD 5). We hypothesized that growth‐limiting conditions would result in higher cell quotas of karlotoxin. KmTx was present in toxic strains during all growth phases and increased in stationary and senescent phase cultures under low N or P, generally 2‐ to 5‐fold but with some observations in the 10‐ to 15‐fold range. No karlotoxin was observed under low‐N or low‐P conditions in the nontoxic strain MD 5. Nutrient‐quality (NO3, NH4, urea, and glycerophosphate) did not affect growth rate, but growth on NH4 produced 2‐ to 3‐fold higher cellular toxicity and a 50% higher ratio of KmTx 1‐1:KmTx 1‐3 in CCMP 1974. CCMP 1974 showed higher cellular toxicity at low salinity (≤5 ppt) and high temperature (25°C). Our results suggested that given the presence of a toxic strain of K. veneficum in situ, the existence of environmental conditions that favor cellular accumulation of karlotoxin is likely a significant factor underlying K. veneficum–related fish kills that require both high cell densities (104 · mL−1) and high cellular toxin quotas relative to those generally observed in nutrient‐replete cultures.
COCCOLITH FUNCTION AND MORPHOGENESIS: INSIGHTS FROM APPENDAGE‐BEARING COCCOLITHOPHORES OF THE FAMILY SYRACOSPHAERACEAE (HAPTOPHYTA)1
Authors: Young Jeremy R. , Andruleit Harald , Probert Ian
Published: February 2009

The morphology of three remarkable genera of coccolithophores,Ophiaster, Michaelsarsia,andCalciopappus,is reviewed based on new images using field emission scanning electron microscopy. Each of these genera characteristically forms coccospheres with long appendages formed of highly modified coccoliths, which radiate from either the circum‐flagellar pole of the coccosphere (CalciopappusandMichaelsarsia) or the antapical pole (Ophiaster). For each genus, it is shown that the appendage coccoliths can also occur in an alternative orientation appressed to the main coccosphere. It is hypothesized that the appendage coccoliths are initially deployed in the appressed orientation and that extension of the appendages is a dynamic response to environmental stress. The observations suggest that coccoliths are more sophisticatedly adapted to specific functions than has been assumed and that the cytoskeleton plays more active roles in coccolith morphogenesis and deployment than has previously been inferred.
Hepatitis C virus (HCV)‐specific T‐cell responses among recombinant immunoblot assay‐3–indeterminate blood donors: a confirmatory evidence of HCV exposure
Authors: Bes Marta , Esteban Juan Ignacio , Casamitjana Natàlia , Piron Maria , Quer Josep , Cubero María , Puig Lluís , Guardia Jaime , Sauleda Sílvia
Published: February 2009

BACKGROUND: Blood donors are routinely screened for hepatitis C virus (HCV) infection. Some show weak anti‐HCV responses, often restricted to a single antigen on confirmatory immunoblot (recombinant immunoblot assay [RIBA]) testing. The aim of this study was to investigate the extent to which such RIBA‐indeterminate donors had previously been exposed to HCV.

STUDY DESIGN AND METHODS: T‐cell responses to HCV recombinant proteins (core, NS3, and NS3 helicase) were analyzed using an interferon‐γ (IFN‐γ) enzyme‐linked immunospot (ELISpot) assay and quantification of cytokines in culture supernatants in 27 RIBA‐indeterminate donors, 60 RIBA‐confirmed donors (48 with and 12 without HCV RNA), and 30 RIBA‐negative donors.

RESULTS: HCV‐specific T‐cell responses were identified in 13 (48%) RIBA‐indeterminate donors, 33 (55%) RIBA‐confirmed donors, and 4 (13%) RIBA‐negative controls (p = 0.008 and p < 0.001, respectively). The magnitude of the T‐cell response among indeterminate donors was similar to that of RIBA‐confirmed donors for all HCV antigens and the specificity of the ELISpot results was confirmed by antigen‐specific cytokine production (interleukin‐2 and IFN‐γ) in short‐term culture supernatants.

CONCLUSIONS: These findings confirm that approximately half of RIBA‐indeterminate donors have resolved a previous HCV infection and suggest that ELISpot might be a useful tool to clarify the status of such donors and help in their counseling and management.
The Future of Nuclear Power: Value Orientations and Risk Perception
Authors: Whitfield Stephen C. , Rosa Eugene A. , Dan Amy , Dietz Thomas
Published: February 2009

Since the turn of the 21st century, there has been a revival of interest in nuclear power. Two decades ago, the expansion of nuclear power in the United States was halted by widespread public opposition as well as rising costs and less than projected increases in demand for electricity. Can the renewed enthusiasm for nuclear power overcome its history of public resistance that has persisted for decades? We propose that attitudes toward nuclear power are a function of perceived risk, and that both attitudes and risk perceptions are a function of values, beliefs, and trust in the institutions that influence nuclear policy. Applying structural equation models to data from a U.S. national survey, we find that increased trust in the nuclear governance institutions reduces perceived risk of nuclear power and together higher trust and lower risk perceptions predict positive attitudes toward nuclear power. Trust in environmental institutions and perceived risks from global environmental problems do not predict attitudes toward nuclear power. Values do predict attitudes: individuals with traditional values have greater support for, while those with altruistic values have greater opposition to, nuclear power. Nuclear attitudes do not vary by gender, age, education, income, or political orientation, though nonwhites are more supportive than whites. These findings are consistent with, and provide an explanation for, a long series of public opinion polls showing public ambivalence toward nuclear power that persists even in the face of renewed interest for nuclear power in policy circles.
Improving Risk‐Based Decision Making for Terrorism Applications
Authors: Cox, Jr Louis Anthony
Published: February 2009

How can we best allocate limited defensive resources to reduce terrorism risks? Dillon et al.'s Antiterrorism Risk‐Based Decision Aid (ARDA) system provides a useful point of departure for addressing this crucial question by exhibiting a real‐world system that calculates risk reduction scores for different portfolios of risk‐reducing countermeasures and using them to rank‐order different possible risk mitigation alternatives for Navy facilities. This comment points out some potential limitations of any scoring system that does not take into account risk externalities, interdependencies among threats, uncertainties that are correlated across targets, and attacker responses to alternative allocations of defensive resources. In at least some simple situations, allocations based on risk reduction scores and comparisons can inadvertently increase risks by providing intelligent attackers with valuable information, or they can fail to reduce risks as effectively as nonscoring, optimization‐based approaches. These limitations of present scoring methods present exciting technical challenges and opportunities for risk analysts to develop improved methods for protecting facilities and infrastructure against terrorist threats.
Low‐Temperature Densification of TiN–TiB2 Composites Through Reactive Hot Pressing with Excess Ti Additions
Authors: Rangaraj Lingappa , Divakar Canchi , Jayaram Vikram
Published: February 2009

Reactive hot pressing of Ti and BN powder mixtures is used to produce dense TiNx–TiB2 composites. The effect of excess Ti along with a small addition, ∼1 wt% Ni, on the reaction and densification of the composite was investigated. A composite of ∼99.9% relative density (RD) was produced at 1200°C at 40 MPa for 30 min with 1 wt% Ni, whereas composites produced without Ni are porous and contain residual reactants. The microstructural studies on composite samples with excess Ti produced at short durations indicate the presence of a transient (Ni–Ti) phase from which Ti is finally removed to form substoichiometric TiNx. The hardness of the dense TiNx–TiB2 composite is ∼22 GPa. The densification mechanism in this system is contrasted with the role of nonstoichiometry in the Zr–B4C system.
Molten Salt Synthesis of Bi4(V0.85Co0.15)2O11−δ (BICOVOX) Ceramic Powders
Authors: Roy B. , Fuierer Paul Anton
Published: February 2009

Cobalt (15 at.%)‐doped bismuth vanadate, Bi4(V0.85Co0.15)2O11−δ (BICOVOX) is known to have high oxygen ion conduction. However, the conductivity is highly anisotropic due to its layered structure. In this paper, we report the synthesis of BICOVOX powders with platelet habit by molten salt synthesis using a NaCl–KCl eutectic mixture as the reaction medium. The effects of treatment temperature and time on the morphology and phase content of the BICOVOX powders were investigated. By this method, it is possible to synthesize powders with platelets of major face dimension ∼50 μm and aspect ratio (major face dimension to thickness) as high as 15.
Oxidation of ZrB2–SiC: Influence of SiC Content on Solid and Liquid Oxide Phase Formation
Authors: Karlsdottir Sigrun N. , Halloran John W.
Published: February 2009

The effect of SiC concentration on the liquid and solid oxide phases formed during oxidation of ZrB2–SiC composites is investigated. Oxide‐scale features called convection cells are formed from liquid and solid oxide reaction products upon oxidation of the ZrB2–SiC composites. These convection cells form in the outermost borosilicate oxide film of the oxide scale formed on the ZrB2–SiC during oxidation at high temperatures (≥1500°C). In this study, three ZrB2–SiC composites with different amounts of SiC were tested at 1550°C for various durations of time to study the effect of the SiC concentration particularly on the formation of the convection cell features. A calculated ternary phase diagram of a ZrO2–SiO2–B2O3 (BSZ) system was used for interpretation of the results. The convection cells formed during oxidation were fewer and less uniformly distributed for composites with a higher SiC concentration. This is because the convection cells are formed from ZrO2 precipitates from a BSZ oxide liquid that forms upon oxidation of the composite at 1550°C. Higher SiC‐containing composites will have less dissolved ZrO2 because they have less B2O3, which results in a smaller amount of precipitated ZrO2 and consequently fewer convection cells.
Mechanical and Thermophysical Properties of Zr–Al–Si–C Ceramics
Authors: He Ling‐Feng , Bao Yi‐Wang , Wang Jing‐Yang , Li Mei‐Shuan , Zhou Yan‐Chun
Published: February 2009

The mechanical and thermophysical properties of quaternary‐layered carbides, Zr2[Al(Si)]4C5 and Zr3[Al(Si)]4C6 have been investigated and compared with those of Zr2Al3C4 and Zr3Al3C5. These four carbides are generally alike in mechanical and thermophysical properties due to their similar crystal structures that consisting of alternatively stacked ZrC layers and Al3C2/[Al(Si)]4C3 slabs. The layer thickness of zirconium carbide and aluminum carbide has effects on their properties. Thicker layer of zirconium carbide and/or thinner layer of aluminum carbides are in favor of stiffness, hardness, thermal, and electrical conductivities, but go against density, specific stiffness, Debye temperature, and coefficient of thermal expansion.
Development and Characterization of Porous Composites for Solid Oxide Fuel Cell Anode Conduction Layers Using Ceramic‐Filled Highly Porous Ni Foam
Authors: Corbin Stephen F. , Clemmer Ryan M. C. , Yang Quan
Published: February 2009

Porous Ni‐yttria stabilized zirconia (YSZ) composites are the most common materials used for solid oxide fuel cell anodes. In conventional anodes, percolation of the Ni phase for acceptable conductivity requires relatively high Ni contents (i.e., >35 vol% of solids) which can reduce cell reliability due to increased coefficient of thermal expansion (CTE) mismatch with the YSZ electrolyte and damage produced by redox cycling. In this study, the incorporation of highly porous Ni foam into an anode structure was investigated in order to produce an anode conduction layer with high conductivity values at lower Ni volumes. This was done by developing techniques for pasting various YSZ based slurries into a Ni foam structure followed by sintering. The electrical conductivity, dimensional stability, and CTE of these structures were measured as a function of Ni, YSZ, and porous volume. Sintered anodes made with Ni‐foam exhibited a superior combination of conductivity and CTE compared with conventional anode structures. For example, a Ni foam–YSZ composite with a nickel loading of 13 vol% has a CTE of 10.7 × 10−6 K−1, but with a similar electrical conductivity to a conventional anode (∼3000 S/cm) which requires at least 30 vol% Ni resulting in a CTE >13 × 10−6 K−1. Alteration of the paste composition produced a porous composite with engineered porosity and good dimensional stability.
Facile Synthesis of Si3N4 Nanocrystals Via an Organic–Inorganic Reaction Route
Authors: Zhu Hui‐Ling , Han Fu‐Dong , Bi Jian‐Qiang , Bai Yu‐Jun , Qi Yong‐Xin , Pang Lin‐Lin , Wang Cheng‐Guo , Li Shao‐Jie , Lu Cheng‐Wei
Published: February 2009

Silicon nitride (Si3N4) nanocrystals were synthesized at about 250°C by a simple organic–inorganic reaction between CH3SiCl3 and NaN3. The yield of Si3N4 is no <70 wt% based on the amount of precursor CH3SiCl3 used in the reaction and TGA analysis. X‐ray diffraction indicates the formation of a mixture of α‐ and β‐Si3N4. Particles with size from 40 to 100 nm are dominant in the products examined by transmission electron microscopy. X‐ray photoelectron spectroscopy gives an atomic ratio of Si:N around 0.75:1. The formation of nanocrystalline Si3N4 during the organic–inorganic reaction goes through an intermediate product of NaSi2N3, which is important for understanding the reaction mechanism.
Fabrication of Millimeter‐Wave Electromagnetic Bandgap Crystals Using Microwave Dielectric Powders
Authors: Lu Xuesong , Lee Yoonjae , Yang Shoufeng , Hao Yang , Ubic Rick , Evans Julian R. G. , Parini Clive G.
Published: February 2009

Electromagnetic bandgap (EBG) structures active in the 90–110 GHz region widely used by security imaging radar were created using different ceramics by a rapid prototyping method informed by finite difference time domain modeling. This solid free‐forming method uses a high volatility solvent‐based ceramic paste extruded through fine nozzles allowing ceramic powders to be assembled on a multiaxis building platform avoiding machining, etching, or the alignment of loose rods and created to designs downloaded directly from a computer file. Lattices were made from two high dielectric constant ceramics: La(Mg0.5, Ti0.5)O3and (Zr0.8, Sn0.2)TiO4and compared with those of Al2O3demonstrating three EBG structures with different dimensions and dielectric constants but with the same bandgap. The effects of manufacturing tolerances on bandgap frequency are investigated by simulation.
Sr3LaNb3O12: A New Low Loss and Temperature Stable A4B3O12‐Type Microwave Dielectric Ceramic
Authors: Fang Liang , Zhang Hui , Yu Qian , Su Heping , Wu Bolin , Cui Xueming
Published: February 2009

The microwave dielectric properties of dense ceramics of a new A4B3O12type cation‐deficient hexagonal perovskite Sr3LaNb3O12are reported. Single‐phase powders can be obtained from the mixed‐oxide route at 1320°C and dense ceramics (>96% of the theoretical X‐ray density) with uniform microstructures (5–12 um) can be obtained by sintering in air at 1430°C. The ceramic exhibits a moderate dielectric constant ɛr∼36, a high quality factorQ×f∼45 327 GHz, and a low temperature coefficient of resonant frequency τfof −9 ppm/°C.
Anthropology and the Beijing Olympics
Authors: Brownell Susan
Published: February 2009

Janine R Wedel is contributing editor of “Research on Policy,” the AAA Interest Group for the Anthropology of Public Policy column in Anthropology News.
A UVB phototherapy protocol with very low dose increments as a treatment of atopic dermatitis
Authors: Wulf H. C. , Bech‐Thomsen N.
Published: February 2009

From 1991 to 1992, 15 patients with atopic dermatitis were treated with a new UVB treatment regimen guided by skin reflectance measurements. The new treatment was characterized by very low dose increments from start to end of therapy. The median cumulative dose increment during therapy was only 20%. The severity of the disease, the efficacy of the treatment, the occurence of adverse effects and the cumulative UVB dose were obtained from the case records. This data were compared in an open study with the data obtained from 17 patients with atopic dermatitis who were treated from 1988 to 1991 at the department with a standard UVB treatment regimen with stepwise dose increments. There was no difference in the severity of the disease at the beginning of the therapy between the two groups. The skin reflectance‐guided low‐dose UVB therapy was not significantly faster (3.5 weeks) than the regimen with stepwise dose increments (4.5 weeks). The cumulative UV exposure was four times lower with the new treatment regimen (34 standard erythema doses) compared with the old regimen (161 standard erythema doses), P<0.001. The healing score was significantly higher with the new treatment regimen compared with the old, P<0.05. This study indicates that skin reflectance‐guided UVB phototherapy may enable the dermatologist to lower the cumulative UVB exposure significantly without losing effect.
A hazard assessment of artificial tanning units
Authors: Moseley H. , Davidson M. , Ferguson J.
Published: February 2009

As a result of increasing concern over the use of artificial tanning units, many local government recreation departments are phasing out the use of sunbeds on their premises, resulting in some clients switching to high street parlours about which little is known. An Environmental Health survey was conducted in all 32 tanning premises within a local government area (Perth & Kinross, Scotland). A number of significant problems emerged in the private sector. In this group, there was no form of cumulative UV exposure control in 89% of premises and 81% failed to give adequate advice and information to customers. We conducted UV spectral irradiation measurements in 38 tanning units using a double grating spectroradiometer. When a carcinogenic weighting factor was applied to these measurements, it was found that a 10 min exposure in a high intensity stand‐up cabinet carried the same carcinogenic risk as approximately 30 min of local (56° North) mid‐day summer sunlight or 10 min of Mediterranean sunlight at mid‐day. A questionnaire completed by 57 customers revealed a wide pattern of usage; 6 (10%) had more than 20 h exposure in the previous 12 months and 3 (5%) had made regular use of sunbeds for the previous 16 to 20 years. These results indicate that there is a need for continuing public education and surveillance of commercial artificial tanning units.
Measurement of cutaneous erythema by means of photodensitometry: application to cutaneous photosensitivity
Authors: Demange L. , Léonard F. , Morel M. , Kalis B.
Published: February 2009

We have developed a photodensitometry method to evaluate the intensity of cutaneous erythema objectively. The method measures the optical density of photographic slides of cutaneous erythema. It combines techniques used commonly but separately by investigators: diffuse transmittance spectroscopy (which is a variant of diffuse reflectance spectroscopy) and photography. We have used this method to study photosensitivity in 22 volunteers who received increasing doses of ultraviolet radiation to the back. Our work confirms the usefulness of an important parameter in photobiology: the regression slope of the curve representing the erythema index, a function of the logarithm of the dose applied.
Changes of minimal erythema dose after water and salt water baths
Authors: Gambichler T. , Schröpl F.
Published: February 2009

Knowledge about the influence of salt water baths on UV irradiation, especially balneophototherapy, is incomplete. The aim of this study was to investigate the influence of various concentrated salt solutions on the minimal erythema dose (MED). We determined the MEDdry (UVB) in 24 healthy, previously UV unexposed subjects on the inner forearm. Subjects were divided randomly into two groups of 12. Subsequently, the MEDwet was assessed on each forearm after 30 min tap water or 5% salt water bath (group A), respectively, or after 30 min 10% or 20% salt water bath (group B), respectively. Compared with the MEDdry, a significantly decreased MEDwet, was observed after all exposures (group A?F= 18.94; P<0.001; group B?F=11.73; P<0.006). A maximal relative decrease in MEDdry of about 51.4% was observed after the 10% salt water bath. The 5% salt solution caused a modest relative decrease in MEDwet of 23.4%. We observed a markedly increased photosensitivity to UVB after all exposures, without a linear correlation between the MED and the salt water concentration. A determination of MED during balneophototherapy should be carried out after bathing in order to reduce the cumulative UV dose and to prevent acute photodamage.
A comparison of erythema efficacy of ultraviolet B irradiation from Philips TL12 and TL01 lamps
Authors: Leenutaphong V. , Sudtim S.
Published: February 2009

The erythema efficacy of UVB irradiation from Philips TL12 and TL01 lamps has been evaluated and compared. Thirty‐seven healthy Thai volunteers were irradiated on the previously unexposed lower back with TL12 and TL01 lamps in doses ranging 100 to 550 mJ/cm2 and 360 to 2020 mJ/cm2, respectively. Erythema was evaluated clinically and measured by a narrow‐band spectrophotometer before exposure and 24 h after exposure. The threshold doses of UVB that induced barely perceptible erythema (MEDb) with well‐defined border erythema (MEDw) and the steepness of the dose‐response curves for erythema (DRAE) were compared. We found that MEDb and MEDw of the TL01 lamps were 4.19 and 4.52 times those of TL12 lamps, which were similar to those calculated from the CIE erythema action spectrum (4.2). However, the DRAE of the two lamps were quite similar. Because the initial dosage of UVB phototherapy is usually given as a percentage of a patient's MED, the initial exposure of TL01‐UVB phototherapy should be about 4.2 times that of TL12‐UVB.
Meloxicam in acute UV dermatitis — a pilot study
Authors: Bayerl C. , Pagung R. , Jung E. G.
Published: February 2009

The non‐steroidal anti‐inflammatory drug (NSAID) meloxicam is a preferential cyclooxygenase‐2 (COX‐2) antagonist. The UV protective potential of this drug was studied to compare it with the reported beneficial effects of such preferentially COX‐1 specific NSAIDs as indomethacin and acetylsalicylic acid in the literature. In a pilot study (open‐label, non‐randomized, non‐controlled, unblinded), 10 patients received UV irradiation with the minimal erythema dose (MED), first with meloxicam (7.5 mg/die) to reduce post‐operative pain and second without ingestion of meloxicam. The factor of UV protection was evaluated. In six of ten patients meloxicam showed no benefit, whereas four of ten patients had a 1.3‐ up to 3‐fold UV protection. In this study, the benefit in UV protection of meloxicam as a prefential COX‐2 antagonist was not above the reported benefit of the “old” COX‐1 inhibiting NSAIDS.
PUVA‐bath photochemotherapy (PUVA‐soak therapy) of recalcitrant dermatoses of the palms and soles
Authors: Behrens S. , von Kobyletzki G. , Gruss C. , Reuther T. , Altmeyer P. , Kerscher M.
Published: February 2009

PUVA‐bath therapy has proven to avoid many side effects associated with oral 8‐methoxypsoralen (8‐MOP) treatment. In order to investigate the effectiveness of topical PUVA‐bath therapy (PUVA‐soak therapy) on chronic palmoplantar dermatoses, 30 patients with plaque‐type psoriasis, pustular psoriasis, endogenous eczema, dyshidrotic eczema and hyperkeratotic dermatitis of the palms and soles were treated over 8 weeks with PUVA‐soak using 8‐MOP. No additional treatment except skin moisturising cream such as unguentum emulsificans aquosum was used during the study period. The single UVA‐doses applied ranged from 0.3 to 3.0 J/cm2 (mean single dose of 1.8 J/cm2), with a mean cumulative dose of 48.6 J/cm2 per patient. Altogether 26 of 30 patients responded well within 8 weeks of treatment with 63% of all patients showing a complete remission and 23% showing considerable improvement, as shown by flattening of plaques, decreased scaling and erythema, as well as decreased vesicle and pustule formation. The condition responding best to our therapy was palmoplantar psoriasis followed by atopic eczema. Hyperkeratotic dermatitis displayed the poorest responding rates in this study. Unwanted side effects such as erythema, pain, blistering or patchy hyperpigmentation were not observed in any of the patients. We conclude that PUVA‐soak therapy can be highly efficient in the treatment of palmoplantar dermatoses, especially in the management of palmoplantar psoriasis.
Sunbed use in Buenos Aires, Argentina
Authors: Chouela E. , Pellerano G. , Bessone A. , Ducard M. , Poggio N. , Abeldaño A.
Published: February 2009

The objectives were to survey tanning salons in a defined geographic area of Buenos Aires city and to assess the information offered to consumers regarding chronic exposure to ultraviolet radiation, types of radiation used, and safety measures employed. A prospective study using a standardized interview with limited multiple choice responses for data collection was conducted. Results of the interview survey were that 35% of the establishments (tanning salons) said they used UVA exclusively, 6% UVB, and 25% both; 35% did not know the type of radiation to which their clients were exposed. Sunbeds were promoted as healthy in 56% of the tanning salons, whereas potential risks were mentioned in only 15%. One to 3 sessions on the same day were allowed by 84%, while 40% allowed customers to choose the number of weekly sessions. The use of goggles was optional in 65% of the establishments and 21% did not even provide goggles. Use of sunscreens was not compulsory, and none of the salons had associated physicians. Previous history of skin cancer, sunburn or potential photosensitive drug intake were never recorded, and the age of access was not restricted in 71% of the establishments. In Argentina there are no guidelines to regulate the operation of tanning salon establishments or the equipment they use, and there are no specific measures taken to prevent skin and ocular pathologies. Ways to reduce the risks of ocular and skin pathologies from artificial tanning in Argentina are urgently needed.
Protection against endogenous and UVB‐induced oxidative damage in stratum corneum lipids by an antioxidant‐containing cosmetic formulation
Authors: Pelle E. , Muizzuddin N. , Mammone T. , Marenus K. , Maes D.
Published: February 2009

A 16‐week human clinical study was carried out to determine the ability of antioxidants in a cosmetic vehicle to inhibit the induction of lipid peroxidation in stratum corneum lipids. The study consisted of a twice daily application of material for 12 weeks followed by a 4‐week regression phase. Stratum corneum lipids were collected and then exposed to 500 mJ/cm2 of ultraviolet B (UVB) radiation in order to avoid excessive erythemal damage to the subjects. Lipid peroxides were assayed by a methylene blue derivative assay and expressed per unit area of skin. During the treatment period, decreases in the level of lipid peroxides were observed on the sites treated with the compositions containing antioxidants, as compared to the untreated sites, and expressed as percent differences. Decreases were observed in endogenous as well as UV‐induced lipid peroxides followed by a return to baseline levels. These results demonstrate that antioxidants in a topical cosmetic formulation were effective in protecting human stratum corneum lipids against endogenous oxidation or if challenged by 500 mJ/cm2 UVB.
Xeroderma pigmentosum variant associated with multiple cancers
Authors: Kuwamoto K. , Miyauchi‐Hashimoto H. , Isei T. , Horio T.
Published: February 2009

A 62‐year‐old Japanese man with xeroderma pigmentosum (XP) variant is reported. The patient had developed at least 6 basal cell carcinomas, a squamous cell carcinoma, and a malignant melanoma on sun‐exposed areas, and an atypical carcinoid on the right lung. In vivo phototesting showed a normal response. The minimal erythema dose of ultraviolet B (UVB) was not lowered and no delayed peaking of the erythema reaction was observed. His skin fibroblasts exhibited higher sensitivity to UV irradiation, but a normal level of unscheduled DNA and RNA synthesis. Cell fusions with XP group A, C, D, E, F, and G cells after UV irradiation were all complemented. Previous reports together with this case suggest that older XP variant patients have a high frequency of not only skin cancers, but also internal malignancies.
UV transmission and UV protection factor (UPF) measured on split skin following exposure to UVB radiation — correlation with the minimal erythema dose (MED)
Authors: Hoffmann K. , Kaspar K. , von Kobyletzki G. , Stücker M. , Altmeyer P.
Published: February 2009

In this study the ultraviolet (UV) transmission of split skin exposed to UVB radiation and of non‐exposed skin was compared in the 280–390 nm wavelength range and quantified. In addition, the correlation between the increase in the minimal erythema dose (MED) associated with a defined exposure to UVB and the ultraviolet protection factor (UPF) calculated from the transmission data was investigated. The study population consisted of 12 patients. Two pieces of split skin of the same thickness (0.3 mm) were taken from the right thigh of each patient. One specimen was removed from an area of non‐exposed healthy skin and the other from an area which had been exposed to UVB radiation for a period of 12 days in which the initial dose of 1/3 MED was raised by 1/3 MED every 4 days. The split skin specimens were stretched over a special frame; subsequently, the UV transmission was determined with a spectrophotometer. The mean values obtained for UV transmission were all significantly below the initial data for non‐exposed split skin. In the UV range of 280–390 nm, the transmission measured in the exposed specimens was 49.1% of the value measured in the non‐exposed split skin (P<0.05). The corresponding values for the UVA range (315–390 nm) and the UVB range (280315 nm) were 50.1% and 29.5%, respectively (P<0.05), based on the initial transmission data obtained from non‐exposed skin. The clinical determination of MED after 12 days of exposure to UVB yielded mean values that were 3.2 times the initial values. Moreover, the mean UPFs calculated from the transmission data measured at the end of the 12‐day exposure period were also about three times the initial values. The present study has thus established a significant correlation between the clinical MED values and the UPFs calculated from the transmission data measured following exposure to UVB.
Immediate pigment darkening thresholds of human skin to monochromatic (362 nm) ultraviolet A radiation are fluence rate dependent
Authors: Kollias N. , Bykowski J. L.
Published: February 2009

When human skin is irradiated with ultraviolet radiation (340–100 nm) there is an immediate pigment response, termed Immediate Pigment Darkening (IPD). This reaction is thought to be due to photooxidation of preexisting melanin, precursors and/or melanin metabolites because it appears during exposure. It has been demonstrated that UVA‐induced skin reactions, including erythema and pigmentation, are oxygen dependent. Therefore, these reactions should also be irradiance (fluence rate) dependent. The purpose of this investigation was to determine the dependence of the IPD threshold on fluence rate. We exposed the forearm of 12 volunteers (skin type II‐V) to monochromatic UVA radiation (362 nm) at a range of fluence rates of 6–115 mW/cm2 and determined the fluence at which pigment was perceptible. The threshold fluence for the IPD reaction increased by a factor of 2.7 as the fluence rate increased by a factor of 18. Therefore, we conclude that the IPD reaction following exposure to 362 nm radiation is dependent on fluence rate, and independent of skin type.
Relationship between constitutive skin color and ultraviolet light sensitivity in Koreans
Authors: Lee J. H. , Kim T. Y.
Published: February 2009

The assessment of skin sensitivity to ultraviolet (UV) radiation is important in treating a variety of skin diseases and preventing the deleterious effects of UV Although there are many ways to predict the sensitivity to UVR, controversies exist over their objectivity, correlation, and applicability in various races. For the purpose of evaluating the relationship of skin color and UV responsiveness, this study was performed to assess the validity of constitutive skin color for an individual's UV sensitivity in 80 healthy Korean volunteers. The subjects were divided into two groups: a young‐aged group with 40 subjects aged 20–39 years and an old‐aged group with 40 subjects aged 43–63 years. A minimal erythema dose (MED) of UVB and minimal immediate pigment darkening dose (MIPDD) of UVA were assessed using a fluorescent lamp (Panasol II, National Biologic Co., Twinberg, USA) and a metal‐halide lamp (Dermalight 2001, Mutzhas, Munich, Germany), respectively. The constitutive skin color of buttock was measured with a Minolta Chroma Meter CR‐300 (Osaka, Japan), using the CIE (Commission International de l'Eclairege) L*a*b* system. Of the three L*a*b*, we used the L* value to estimate the skin color. For the MED and L* values, the values were inversely proportionate (P<0.05) in the young‐aged group; however, no correlation existed in the old‐aged group. No relationships existed among Fitzpatrick skin type and MED, skin type and MIPDD. The results of this study indicated that the constitutive skin colors in the young‐aged group can be an objective and adequate predictor of cutaneous UV sensitivity.
Marginal Bone Level Changes and Prosthetic Maintenance of Mandibular Overdentures Supported by 2 Implants: A 5‐Year Randomized Clinical Trial
Authors: Cehreli Murat Cavit , Uysal Serdar , Akca Kivanc
Published: February 2009

Background: Documentation of early loading of mandibular overdentures supported by different implant systems is scarce.

Purpose: This study aimed to compare the biologic and prosthetic outcome of mandibular overdentures supported by unsplinted early‐loaded one‐ and two‐stage oral implants after 5 years of function.

Materials and Methods: Twenty‐eight consecutive patients were screened following an inclusion and exclusion criteria, and randomly allocated to treatment groups. Ball‐retained mandibular overdentures were fabricated on two unsplinted Straumann® (Institut Straumann AG, Basel, Switzerland) and Brånemark® (Nobel Biocare AB, Göteborg, Sweden) dental implants and subjected to an early‐loading protocol. During the 5‐year period, prosthetic complications were recorded. At 5‐years of function, plaque, peri‐implant inflammation, bleeding, and calculus index scores were recorded, and standard periapical radiographs were obtained from each implant for measurement of marginal bone loss.

Results: All implants survived during the observation period. The peri‐implant inflammation, bleeding, and calculus index scores around Straumann and Brånemark implants were similar (p > .05). The marginal bone loss around Brånemark implants (1.21 ± 0.1) was higher than Straumann implants (0.73 ± 0.06) at 5 years of function (p = .002). Kaplan–Meier tests revealed that 1‐ and 5‐year survival of overdentures on Straumann and Brånemark implants were similar (p = .85). Wear of the ball abutment in the Brånemark group was higher than in the Straumann group (p < .05). Complications regarding the retainer and the need for occlusal adjustments were higher in the Straumann group (p < .05). Chi‐square test revealed that the frequency of retightening of the retainer was higher in the Straumann group than in the Brånemark group (p < .05).

Conclusions: Mandibular overdentures supported by unsplinted early‐loaded Straumann and Brånemark implants lead to similar peri‐implant soft tissue and prosthetic outcomes, although higher marginal bone loss could be observed around Brånemark implants after 5 years.
Effect of Implant Design on Preservation of Marginal Bone in the Mandible
Authors: Van de Velde Tommie , Collaert Bruno , Sennerby Lars , De Bruyn Hugo
Published: February 2009

Background: Implant design and surface may have an influence on the marginal bone response during immediate functional loading.

Aim: The purpose of this study was to radiographically study the effect of implant design on marginal bone preservation at immediately loaded implants used for prosthetic rehabilitation of the completely edentulous mandible.

Materials and Methods: A total of 39 patients, previously treated with five implants for support of a full‐arch fixed bridge in the mandible, were included in the study. Either machined Brånemark® implants (Ma) (Nobel Biocare AB, Gothenburg, Sweden) or surface modified Astra Tech® implants with (Mi) or without a microthreaded neck (Ti) (TiOblast, AstraTech AB, Mölndal, Sweden) were used. All fixtures were loaded with a provisional glass fiber or metal‐reinforced screw‐retained restoration within 24 hours. The provisional restorations were replaced by a 12‐unit screw‐retained metal‐ceramic or metal‐resin cantilever bridge after 3 months. Bone loss from baseline to 1 year of loading was measured by means of intraoral radiographs. Only patients with baseline and 1‐year radiographs of all implants were selected for comparison. Statistical analysis was carried out on both patient and implant levels.

Results: The survival rates after 1 year in function were 98.6, 100, and 100% for the Ma, Ti, and Mi implants, respectively. The overall mean bone loss after 1 year was 1.03 mm (SD 0.87; range −0.77 to 2.5). The mean bone loss was calculated to 1.52 (SD 0.66) for the Ma group, 0.79 (SD 0.79) for the Ti group, and 0.70 (SD 1.01) for the Mi group. There was a significant difference between Ma and Ti (p = .023) and between Ma and Mi (p = .046) groups but not within Ti and Mi implants (p = .70). These conclusions were also valid when the statistical analysis was performed on implant level.

Conclusions: There is no impact of design and surface on implant survival in the completely edentulous mandible. Bone preservation in immediately loaded implants in the mandible is influenced by implant design and significantly better on surface‐modified AstraTech implants compared with machined Brånemark implants. In the mandible, a microthread design of the implant collar does not seem to improve bone preservation.