Atmosphere-Snow Exchange Explains Surface Snow Isotope Variability.

The climate signal imprinted in the snow isotopic composition allows to infer past climate variability from ice core stable water isotope records. The concurrent evolution of vapor and surface snow isotopic composition between precipitation events indicates that post-depositional atmosphere-snow humidity exchange influences the snow and hence the ice core isotope signal. To date, however, this is not accounted for in paeleoclimate reconstructions from isotope records. Here we show that vapor-snow exchange explains 36% of the summertime day-to-day δ18O variability of the surface snow between precipitation events, and 53% of the δD variability. Through observations from the Greenland Ice Sheet and accompanying modeling we demonstrate that vapor-snow exchange introduces a warm bias on the summertime snow isotope value relevant for ice core records. In case of long-term variability in atmosphere-snow exchange the relevance for the ice core signal is also variable and thus paleoclimate reconstructions from isotope records should be revisited.

Non-Equilibrium Fractionation Factors for D/H and 18O/16O During Oceanic Evaporation in the North-West Atlantic Region.

Ocean isotopic evaporation models, such as the Craig-Gordon model, rely on the description of nonequilibrium fractionation factors that are, in general, poorly constrained. To date, only a few gradient-diffusion type measurements have been performed in ocean settings to test the validity of the commonly used parametrization of nonequilibrium isotopic fractionation during ocean evaporation. In this work, we present 6 months of water vapor isotopic observations collected from a meteorological tower located in the northwest Atlantic Ocean (Bermuda) with the objective of estimating nonequilibrium fractionation factors (k, ‰) for ocean evaporation and their wind speed dependency. The Keeling Plot method and Craig-Gordon model combination were sensitive enough to resolve nonequilibrium fractionation factors during evaporation resulting into mean values of k 18 = 5.2 ± 0.6‰ and k 2 = 4.3 ± 3.4‰. Furthermore, we evaluate the relationship between k and 10-m wind speed over the ocean. Such a relationship is expected from current evaporation theory and from laboratory experiments made in the 1970s, but observational evidence is lacking. We show that (a) in the observed wind speed range [0-10 m s-1], the sensitivity of k to wind speed is small, in the order of -0.2‰ m-1 s for k 18, and (b) there is no empirical evidence for the presence of a discontinuity between smooth and rough wind speed regime during isotopic fractionation, as proposed in earlier studies. The water vapor d-excess variability predicted under the closure assumption using the k values estimated in this study is in agreement with observations over the Atlantic Ocean.

Evidence of Isotopic Fractionation During Vapor Exchange Between the Atmosphere and the Snow Surface in Greenland.

Several recent studies from both Greenland and Antarctica have reported significant changes in the water isotopic composition of near-surface snow between precipitation events. These changes have been linked to isotopic exchange with atmospheric water vapor and sublimation-induced fractionation, but the processes are poorly constrained by observations. Understanding and quantifying these processes are crucial to both the interpretation of ice core climate proxies and the formulation of isotope-enabled general circulation models. Here, we present continuous measurements of the water isotopic composition in surface snow and atmospheric vapor together with near-surface atmospheric turbulence and snow-air latent and sensible heat fluxes, obtained at the East Greenland Ice-Core Project drilling site in summer 2016. For two 4-day-long time periods, significant diurnal variations in atmospheric water isotopologues are observed. A model is developed to explore the impact of this variability on the surface snow isotopic composition. Our model suggests that the snow isotopic composition in the upper subcentimeter of the snow exhibits a diurnal variation with amplitudes in δ18O and δD of ~2.5‰ and ~13‰, respectively. As comparison, such changes correspond to 10-20% of the magnitude of seasonal changes in interior Greenland snow pack isotopes and of the change across a glacial-interglacial transition. Importantly, our observation and model results suggest, that sublimation-induced fractionation needs to be included in simulations of exchanges between the vapor and the snow surface on diurnal timescales during summer cloud-free conditions in northeast Greenland.

The environmental and host-associated bacterial microbiota of Arctic seawater-farmed Atlantic salmon with ulcerative disorders.

The Norwegian aquaculture of Atlantic salmon (Salmo salar L.) is hampered by ulcerative disorders associated with bacterial infections. Chronic ulceration may provide microenvironments that disturb the normal microbial biodiversity of external surfaces. Studying the composition of microbial communities in skin ulcers will enhance our understanding of ulcer aetiology. To achieve this, we tested marine farmed Atlantic salmon and sampled the base and edge of ulcers at the end of winter (April) and end of summer (September), in addition to skin mucus of healthy individuals. In order to assess microbiota associated with the host and obtain insight into the environmental ecology, we also sampled sea water, the sediment layer underneath the farm facility and the distal intestine of Atlantic salmon. The skin microbiota of Atlantic salmon was different from that of the surrounding water. Residential Tenacibaculum and Arcobacter species persistently dominated the cutaneous skin and ulcer mucus surfaces of Atlantic salmon during both winter and summer periods. The intestinal microbiota was dominated by Mycoplasma with an increase in Aliivibrio and Alcaligenes abundance in the intestine of fish with ulcerative disorder at the end of winter. These findings suggest the presence of resilient microbes in the mucus surfaces of Atlantic salmon.

The effectiveness of conically shaped compared with cylindrically shaped interdental brushes - a randomized controlled clinical trial.

AIM: The purpose of this study was to compare the effectiveness of conically shaped versus cylindrically shaped interdental brushes (IDB) in patients receiving supportive periodontal therapy. MATERIALS AND METHODS: Periodontal maintenance patients volunteered to be enrolled into this randomized controlled examiner-blind parallel study. At baseline and after 3 months, plaque scores, bleeding upon pocket probing scores and probing pocket depth (PPD) were assessed. The type of IDB (conical or cylindrical) was randomly assigned to each patient and individual instruction was provided regarding the method of use and the appropriate size. Only those approximal sites that had sufficient space for the IDB were eligible, and for those sites the data were analysed separately. Analyses were performed for all eligible approximal surfaces and a sub-analysis was performed for vestibular and lingual surfaces. RESULTS: In total, 51 participants attended the baseline and the 3-month clinical appointments. Overall, there was no difference between conical and cylindrical IDBs. However, the conical IDB showed significantly higher plaque and bleeding scores at the lingual approximal sites. The cause of this difference was an increase in plaque and bleeding scores compared with baseline. With respect to the PPD, no difference between the IDBs was observed. CONCLUSION: Within the limitations of this experiment, the conical IDBs are less effective than cylindrical IDBs with respect to lingual approximal plaque removal. Thus, in patients receiving supportive periodontal therapy, the cylindrical shape should be the first choice of IDB to obtain and maintain gingival health around natural teeth.

Ice-vapor equilibrium fractionation factor of hydrogen and oxygen isotopes: experimental investigations and implications for stable water isotope studies.

RATIONALE: The equilibrium fractionation factors govern the relative change in the isotopic composition during phase transitions of water. The commonly used results, which were published more than 40 years ago, are limited to a minimum temperature of -33°C. This limits the reliability in cold regions. With recent instrumental developments it is now possible to test the accuracy of the earlier results as well as extend the temperature range. METHODS: Novel measurements were made of the ice-vapor equilibrium fractionation factor α between 0°C and -40°C, from a unique experimental setup using both a Picarro cavity ringdown spectrometer and a TC/EA IRMS system. Using both systems allows for continuous monitoring of the equilibrium state of the system as well as testing for reproducibility. RESULTS: The results of the experiments show fractionation factors for δ(2) H and δ(18) O values, with a temperature dependency in accordance with theory for equilibrium fractionation. We obtain the following expressions for the temperature dependency of the fractionation coefficients: ln(αδ2H)=0.2133-(203.10/T+(48888/T2 ln(αδ18O)=0.0831-(49.192/T)+(8312.5/T2). Compared with previous experimental work, a significantly larger α for δ(2) H is obtained while, for δ(18) O, α is larger for temperatures below -20°C and slightly lower for temperatures above this. CONCLUSIONS: Using the new values for α, a Rayleigh distillation model shows significant changes in both magnitude and shape of an annual deuterium excess signal in Greenland. This emphasizes the importance of a well-defined value of α for accurate studies of the processes in the hydrological cycle and underlines the significance of the differences between the results of this work and earlier work.

Influence of air intake on the concentration of free fatty acids and vacuum fluctuations during automatic milking.

The main objective of the study was to determine whether the amount of air intake during quarter milking influences the concentration of free fatty acids (FFA) and vacuum fluctuations at the teat end when milking automatically. Air intake in the teat cup was restricted from the normal inlet of 4.5 to 7 L/min to 1.7 and 0 L/min on 2 farms and experiments were carried out as half-udder studies with 40 cows. Blockage of the air inlet reduced FFA from 1.02 to 0.77 mEq/100 g of fat in one herd and from 1.50 to 1.17 mEq/100 g of fat in the other herd. Milk yield per milking was the most significant factor influencing FFA. Air intake accounted for <20% of the variation in FFA concentration. Characteristics of the cow explained the most variation, which could mainly be assigned to the effects of milk yield, fat percentage, fat globule size, and fat globule size distribution. The interval between milkings was not significant when adjusting for milk yields. Blockage of the air inlet caused vacuum fluctuations at the teat end to increase from 15.4 to 21.5 kPa for one model of an automatic milking system (AMS), but from 12.8 to 53.6 kPa for another model. Measurements made with a flow simulator and water revealed that the AMS model and water flow were the most important factors influencing vacuum fluctuations, and that interactions existed between the diameter of the short milk tube and air intake. Free fatty acids in bulk milk from 5,980 herds averaged 0.75 mEq/L of milk for conventional herds and varied from 0.77 to 0.94 mEq/L of milk for the 5 AMS models on the Danish market. Fault detection in 55 herds pointed out that the most frequent faults in conventional herds were air leakages and intake of too much air in the cluster, whereas AMS herds had problems with the cooling and stirring of milk. Correction of the cooling faults caused FFA to decrease by 0.52 mEq/L in the AMS herds. We concluded that air intake during automatic milking is not the most important factor in reducing FFA, whereas milk yield per milking matters the most. More attention should be paid to the cooling and stirring of milk. Reducing the air intake causes vacuum fluctuations during milking to increase significantly.

Neisseria gonorrhoeae PilV, a type IV pilus-associated protein essential to human epithelial cell adherence.

Type IV pili (Tfp) of Neisseria gonorrhoeae, the Gram-negative etiologic agent of gonorrhea, facilitate colonization of the human host. Tfp are assumed to play a key role in the initial adherence to human epithelial cells by virtue of the associated adhesin protein PilC. To examine the structural and functional basis for adherence in more detail, we identified potential genes encoding polypeptides sharing structural similarities to PilE (the Tfp subunit) within the N. gonorrhoeae genome sequence database. We show here that a fiber subunit-like protein, termed PilV, is essential to organelle-associated adherence but dispensable for Tfp biogenesis and other pilus-related phenotypes, including autoagglutination, competence for natural transformation, and twitching motility. The adherence defect in pilV mutants cannot be attributed to reduced levels of piliation, defects in fiber anchoring to the bacterial cell surface, or to unstable pilus expression related to organelle retraction. PilV is expressed at low levels relative to PilE and copurifies with Tfp fibers in a PilC-dependent fashion. Purified Tfp from pilV mutants contain PilC adhesin at reduced levels. Taken together, these data support a model in which PilV functions in adherence by promoting the functional display of PilC in the context of the pilus fiber.

Randomized controlled trial of vestibular rehabilitation combined with cognitive-behavioral therapy for dizziness in older people.

OBJECTIVE: To evaluate the effectiveness of vestibular rehabilitation combined with cognitive behavioral therapy in the treatment of dizziness in older people. STUDY DESIGN AND SETTING: A randomized controlled design was used with patients recruited via an advertisement. Nine patients completed treatment and 10 served as waiting-list controls. The intervention lasted 7 weeks with 5 weekly group sessions and consisted of vestibular exercises. Cognitive behavioral therapy components were added to promote relaxation, reduce anxiety, and avoidance of feared situations and movements. RESULTS: Statistically significant improvements on walking time, 2 dizziness provocative movements, and on the Dizziness Handicap Inventory, but no effects on the Romberg or anxiety and depression. Of the treated patients, 89% reached statistical significant improvement on the total inventory score. CONCLUSION: Cognitive behavioral therapy combined with vestibular rehabilitation decreases dizziness in older people. SIGNIFICANCE: These findings indicate that cognitive behavioral therapy can be combined with vestibular rehabilitation in the treatment of dizziness.

Longitudinal follow-up of tinnitus complaints.

OBJECTIVE: To investigate the long-term outcome of patients with tinnitus, the long-term effects of cognitive behavioral therapy, and what properties of tinnitus predict distress at follow-up. DESIGN: A longitudinal follow-up of a consecutive sample of patients with tinnitus initially seen by a clinical psychologist. SETTING: Department of Audiology, University Hospital, Uppsala, Sweden. PARTICIPANTS: A consecutive series of 189 patients with tinnitus treated between January 1988 and March 1995 were sent a postal questionnaire booklet. One hundred forty-six (77 women and 69 men) provided usable responses, in all yielding a 77% response rate. MAIN OUTCOME MEASURES: A questionnaire was derived from a structured interview "Questions About Your Tinnitus." Also included were the Tinnitus Reaction Questionnaire and tinnitus-matching data. RESULTS: Questionnaire data showed that many patients with tinnitus still experienced distress an average of 4.9 years after admission. Tolerance of tinnitus increased over time overall. For patients who had received cognitive behavioral therapy (59%), there was a reduction in tinnitus-related distress. Further, an open-ended question showed that the benefits from treatment outnumbered the deficits. Multiple regression analysis showed that tinnitus maskability at admission was a significant predictor of distress at follow-up. CONCLUSIONS: Severe tinnitus shows some signs of improvement over time, especially when psychological treatment has been given. Tinnitus maskability is an important prognostic factor of future tinnitus annoyance.

Parameters affecting gene expression from the Pm promoter in gram-negative bacteria.

The Pm promoter inserted chromosomally or in broad-host-range replicons based on plasmid RSF1010 or RK2 are useful systems for both high- and low-level expression of cloned genes in several gram-negative bacterial species. The positive Pm regulator XylS is activated by certain substituted benzoic acid derivatives, and here we show that these effectors induce expression of Pm at similar relative ranking levels in both Escherichia coli and Pseudomonas aeruginosa However, the kinetics of expression was not the same in the two organisms. Different carbon sources and dissolved oxygen levels displayed limited effects on expression, but surprisingly the pH of the growth medium was found to be of major importance. By combining the effects of genetic and environmental parameters, expression from Pm could be varied over a ten-thousand- to a hundred-thousand-fold continuous range, and as an example of its applications we showed that Pm can be used to control the xanthan biosynthesis in Xanthomonas campestris.

Pm promoter expression mutants and their use in broad-host-range RK2 plasmid vectors.

By coupling the Pm/xylS promoter system to minimal replicons of the broad-host-range plasmid RK2 we recently showed that such vectors are useful for both high- and low-level inducible expression of cloned genes in gram-negative bacteria. In this report, we extend this potential by identifying point mutations in or near the -10 transcriptional region of Pm. Point mutations leading to gene-independent enhancements of expression levels of the induced state or reduced background expression levels were identified using Escherichia coli as a host. By combining these mutations an additive effect in expression levels from the constructed Pm was observed. The highest induced expression level was obtained by inserting an E. coli consensus sigma70 - 10 recognition region. Most of the remaining activities in the reduced-background mutations appeared to originate from a transcriptional start site other than Pm. The effects of some of these mutations were also analyzed in Pseudomonas aeruginosa and were found to act similarly, but less pronounced in this host.

Social competence and behavioural problems in children with hearing impairment.

The focus in this study is on social competence and behavioural problems in a group (n=57) of hearing-impaired 7- to 12-year-old children. Results were related to hearing status, school placement, and gender. Parent and teacher questionnaires were used to measure two aspects of social competence, prosocial orientation and social initiative, and three aspects of behavioural problems, externalizing, internalizing, and concentration problems. A sample of 214 normally-hearing children was used as a comparison group. Overall, the results showed only minor differences between the two groups, with the exception that the hearing-impaired children showed less social initiative in parent ratings. There were no relationships between social functioning and hearing status or school placement (mainstream vs. special classes for hearing-impaired children) nor any clear pattern of gender differences. These findings indicate that hearing-impaired children in Sweden fare well. The results are discussed in terms of the need for longitudinal studies and possible interventions targeted at social behaviours.

Distinguishing levels of tinnitus distress.

Degrees of tinnitus distress were explored in a sample of 216 patients who completed audiological measures and were assessed in a structured interview conducted by a clinical psychologist. The Klockhoff and Lindblom grading system was used and its inter-rater reliability assessed in a subsample showing a high degree of correspondence. Results from the interview are reported in terms of variability of tinnitus, characteristics of problematic situations, distress caused by tinnitus, possibilities to cope, and other influencing factors. Finally, a set of discriminant analyses were conducted on the data set resulting in a final model which included pitch, minimal masking level (MML), tolerance in relation to onset, and avoidance of situations because of tinnitus. This model correctly classified 73% of the subjects into the two levels of distress (grade II and III). There may be a potential role for MML as an outcome variable in tinnitus treatment research.

Performance in functional balance tests during menopausal hormone replacement: a double-blind placebo-controlled study.

BACKGROUND AND PURPOSE: Recent studies have indicated that oestrogens might have an effect on postural control. The purpose of this study was to investigate the short-term effect of hormone replacement therapy (HRT) on postural control in menopausal women and to analyse the correlation between sway velocity measures and results of functional balance tests. SUBJECTS: 100 menopausal women who were randomized to receive either HRT or placebo for three months were included in the study. METHOD: The balance function was measured with nine different static and dynamic functional balance tests. The sway velocities were measured on a computerized force platform. RESULTS: No significant differences were found between the two groups in the results of the functional balance tests after the three-month placebo-controlled period or in the changes over time. However, some significant improvements occurred within both groups over this three-month period. The correlations between different sway velocities and the results of the functional balance tests were all very low (r < 0.35). CONCLUSION: It can not be concluded that HRT had a positive effect on the performance in the functional balance tests, as some improvement occurred in both groups. The low correlations indicate that the sway velocity and functional balance tests measure different aspects of balance function.

Actual and perceived postural sway during balance specific and non-specific proprioceptive stimulation.

A group of patients with balance complaints (n = 16) was compared with a group of normal subjects (n = 17) by means of posturography, subjective assessments of balance, anxiety and unsteadiness when standing on a force platform with eyes closed. Postural instability was induced by vibratory stimulation of the calf muscles (20, 40, 60, 80 and 100 Hz). As a control condition, the arm (biceps) was stimulated at similar frequencies. In order to control for arousal, blood pressure and heart beat were assessed. Furthermore, questionnaire responses on psychological measures were collected. Results showed clear differences between the groups in terms of imbalance and self-reports. However, the 2 groups displayed similar increases of imbalance during calf stimulation and no increase during arm stimulation. Patients generally rated less increase of unsteadiness when the calf was stimulated than did the controls. No differences in arousal were found between the groups or within conditions. Results are discussed in terms of the proposed desynchrony between symptoms and complaints.

Better postural balance in elderly women receiving estrogens.

OBJECTIVE: The amount of bone mass and the tendency to fall are main risk factors for hip fractures and both deteriorate with advancing age. The dynamics between estrogen exposure and fracture protection seem too rapid to be explained by an effect on bone mass only. Postural balance function may be another potential mechanism for the fracture-protecting effect of estrogens. STUDY DESIGN: We examined 16 long-term users of 17 beta-estradiol implants (20 mg) (mean age 67.9 years and mean duration of treatment 17.3 years [3.3 to 34 years]) and 16 age-matched (+/-2 years) nonusers (mean age 68.3 years). Postural balance (sway velocity) was measured by static posturography before and after blindfolding and application of vibration stimulus (20 to 100 Hz) to the calf muscles to disturb the proprioception and to induce imbalance. RESULTS: Sway velocities were significantly lower in estrogen users than in nonusers (p = 0.0067) and similar to those in young premenopausal women. The differences were accentuated after provocation by blindfolding and by increasing frequencies of vibration stimulus to the calf muscle. Serum levels of estradiol and estradiol/sex hormone-binding globulin were negatively and follicle-stimulating hormone levels positively associated with sway velocity (p = 0.0194, p = 0.0036, and p = 0.0052, respectively) and independent of age (p = 0.02 to 0.005), supporting causality between estrogen exposure and postural balance. CONCLUSIONS: These data indicate that postural balance function is better preserved in long-term estrogen users than in nonusers. Effects on postural balance function may be one mechanism explaining the rapid increase in distal forearm fractures early after menopause and the rapid dynamics between estrogen exposure and hip fracture protection and may potentially reduce the fracture risk in elderly women starting estrogen replacement therapy in spite of marginal increases in bone mass.

Construction and use of a versatile set of broad-host-range cloning and expression vectors based on the RK2 replicon.

The plasmid vectors described in this report are derived from the broad-host-range RK2 replicon and can be maintained in many gram-negative bacterial species. The complete nucleotide sequences of all of the cloning and expression vectors are known. Important characteristics of the cloning vectors are as follows: a size range of 4.8 to 7.1 kb, unique cloning sites, different antibiotic resistance markers for selection of plasmid-containing cells, oriT-mediated conjugative plasmid transfer, plasmid stabilization functions, and a means for a simple method for modification of plasmid copy number. Expression vectors were constructed by insertion of the inducible Pu or Pm promoter together with its regulatory gene xylR or xylS, respectively, from the TOL plasmid of Pseudomonas putida. One of these vectors was used in an analysis of the correlation between phosphoglucomutase activity and amylose accumulation in Escherichia coli. The experiments showed that amylose synthesis was only marginally affected by the level of basal expression from the Pm promoter of the Acetobacter xylinum phosphoglucomutase gene (celB). In contrast, amylose accumulation was strongly reduced when transcription from Pm was induced. CelB was also expressed with a very high induction ratio in Xanthomonas campestris. These experiments showed that the A. xylinum celB gene could not complement the role of the bifunctional X. campestris phosphoglucomutase-phosphomannomutase gene in xanthan biosynthesis. We believe that the vectors described here are useful for cloning experiments, gene expression, and physiological studies with a wide range of bacteria and presumably also for analysis of gene transfer in the environment.

Improved broad-host-range RK2 vectors useful for high and low regulated gene expression levels in gram-negative bacteria.

This report describes the construction and use of improved broad-host-range expression vectors based on the previously constructed pJB137 and pJB653 plasmids (Blatny et al., 1997). These vectors contain the minimal replicon of RK2 and the inducible Pu or Pm promoters together with their regulatory xylR or xylS genes, respectively, from the Pseudomonas putida TOL plasmid pWWO. A set of ATG vectors were derived from pJB653, and these vectors are characterized by the relatively small size, the presence of multiple cloning sites downstream of Pm, the establishment of their nucleotide sequence, the presence of RK2 oriT, and different antibiotic selection markers. The copy numbers of all the vectors can easily be modified by using copy-up mutations of the trfA gene, required for initiation of replication of RK2 replicons. The vectors were used to study the expression levels of the Acetobacter xylinum phosphoglucomutase gene celB and the two commonly used reporter genes luc and cat in Escherichia coli, Pseudomonas aeruginosa, and Xanthomonas campestris. Good induction properties and tight regulation of Pm were achieved in all three species tested, and higher gene expression levels were obtained by using the ATG vectors compared to pJB653. By introducing different trfA copy-up mutations into the vectors, a wide range of gene expression levels from Pu and Pm were obtained in E. coli. Induced expression levels of luc, cat, and celB from Pm were found to be comparable to or higher than those from the Ptrc and PT7 promoters located on high copy number plasmids. The induced levels of Luc activity were higher in P. aeruginosa than in E. coli, indicating that these vectors may be useful for maximization of gene expression in strains other than E. coli. We believe that the well-characterized vectors described here are useful for gene expression studies and routine cloning experiments in many Gram-negative bacteria.