bluuebunny/crossref_metadata_2025 huggingface dataset:
Injection of mineral dust into the free troposphere during fire events observed with polarization lidar at Limassol, Cyprus
Authors: Nisantzi A. , Mamouri R. E. , Ansmann A. , Hadjimitsis D.
Published: November 2014

Abstract. Four-year observations (2010–2014) with EARLINET polarization lidar and AERONET sun/sky photometer at Limassol (34.7° N, 33° E), Cyprus, were used to study the soil dust content in lofted fire smoke plumes advected from Turkey. This first systematic attempt to characterize less than 3-day-old smoke plumes in terms of particle linear depolarization ratio (PDR), measured with lidar, contributes to the more general effort to properly describe the life cycle of free-tropospheric smoke–dust mixtures from the emission event to phases of long-range transport (> 4 days after emission). We found significant PDR differences with values from 9 to 18% in lofted aerosol layers when Turkish fires contributed to the aerosol burden and of 3–13 % when Turkish fires were absent. High Ångström exponents of 1.4–2.2 during all these events with lofted smoke layers, occurring between 1 and 3 km height, suggest the absence of a pronounced particle coarse mode. When plotted vs. travel time (spatial distance between Limassol and last fire area), PDR decreased strongly from initial values around 16–18% (1 day travel) to 4–8% after 4 days of travel caused by deposition processes. This behavior was found to be in close agreement with findings described in the literature. Computation of particle extinction coefficient and mass concentrations, derived from the lidar observations, separately for fine-mode dust, coarse-mode dust, and non-dust aerosol components show extinction-related dust fractions on the order of 10% (for PDR =4%, travel times > 4 days) and 50% (PDR =15%, 1 day travel time) and respective mass-related dust fractions of 25% (PDR =4%) to 80% (PDR =15%). Biomass burning should therefore be considered as another source of free tropospheric soil dust.
Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)
Authors: You Y. , Kanawade V. P. , de Gouw J. A. , Guenther A. B. , Madronich S. , Sierra-Hernández M. R. , Lawler M. , Smith J. N. , Takahama S. , Ruggeri G. , Koss A. , Olson K. , Baumann K. , Weber R. J. , Nenes A. , Guo H. , Edgerton E. S. , Porcelli L. , Brune W. H. , Goldstein A. H. , Lee S.-H.
Published: November 2014

Abstract. We report measurements of ambient amines and ammonia with a fast response chemical ionization mass spectrometer (CIMS) in a southeastern US forest and a moderately polluted midwestern site during the summer. At the forest site, mostly C3-amines (from pptv to tens of pptv) and ammonia (up to 2 ppbv) were detected, and they both showed temperature dependencies. Aerosol-phase amines measured thermal-desorption chemical ionization mass spectrometer (TDCIMS) showed a higher mass fraction in the evening with cooler temperatures and lower in the afternoon with warmer temperatures, a trend opposite to the gas-phase amines. Concentrations of aerosol-phase primary amines measured with Fourier transform infrared spectroscopy (FTIR) from micron and submicron particles were 2 orders of magnitude higher than the gas-phase amines. These results indicate that gas to particle conversion is one of the major processes that control the ambient amine concentrations at this forest site. Temperature dependencies of C3-amines and ammonia also imply reversible processes of evaporation of these nitrogen-containing compounds from soil surfaces in daytime and deposition to soil surfaces at nighttime. During the transported biomass burning plume events, various amines (C1–C6) appeared at the pptv level, indicating that biomass burning is a substantial source of amines in the southeastern US. At the moderately polluted Kent site, there were higher concentrations of C1- to C6-amines (pptv to tens of pptv) and ammonia (up to 6 ppbv). C1- to C3-amines and ammonia were well correlated with the ambient temperature. C4- to C6-amines showed frequent spikes during the nighttime, suggesting that they were emitted from local sources. These abundant amines and ammonia may in part explain the frequent new particle formation events reported from Kent. Higher amine concentrations measured at the polluted site than at the rural forested site highlight the importance of constraining anthropogenic emission sources of amines.
OH-initiated heterogeneous oxidation of tris-2-butoxyethyl phosphate: implications for its fate in the atmosphere
Authors: Liu Y. , Huang L. , Li S.-M. , Harner T. , Liggio J.
Published: November 2014

Abstract. A particle-phase relative rates technique is used to investigate the heterogeneous reaction between OH radicals and tris-2-butoxyethyl phosphate (TBEP) at 298 K by combining aerosol time-of-flight mass spectrometry (C-ToF-MS) data and positive matrix factor (PMF) analysis. The derived second-order rate constants (k2) for the heterogeneous loss of TBEP is (4.44 ± 0.45) × 10−12 cm3 molecule−1 s−1, from which an approximate particle-phase lifetime was estimated to be 2.6 (2.3–2.9) days. However, large differences in the rate constants for TBEP relative to a reference compound were observed when comparing internally and externally mixed TBEP/organic particles, and upon changes in the RH. The heterogeneous degradation of TBEP was found to be depressed or enhanced depending upon the particle mixing state and phase, highlighting the complexity of heterogeneous oxidation in the atmosphere. The effect of gas-particle partitioning on the estimated overall lifetime (gas + particle) for several organophosphate esters (OPEs) was also examined through the explicit modeling of this process. The overall atmospheric lifetimes of TBEP, tris-2-ethylhexyl phosphate (TEHP) and tris-1,3-dichloro-2-propyl phosphate (TDCPP) were estimated to be 1.9, 1.9 and 2.4 days respectively, and are highly dependent upon particle size. These results demonstrate that modeling the atmospheric fate of particle-phase toxic compounds for the purpose of risk assessment must include the gas-particle partitioning process, and in the future include the effect of other particulate components on the evaporation kinetics and/or the heterogeneous loss rates.
High-precision dual-inlet IRMS measurements of the stable isotopes of CO2 and the N2O / CO2 ratio from polar ice core samples
Authors: Bauska T. K. , Brook E. J. , Mix A. C. , Ross A.
Published: November 2014

Abstract. An important constraint on mechanisms of past carbon cycle variability is provided by the stable isotopic composition of carbon in atmospheric carbon dioxide (δ13C-CO2) trapped in polar ice cores, but obtaining very precise measurements has proven to be a significant analytical challenge. Here we describe a new technique to determine the δ13C of CO2 at very high precision, as well as measuring the CO2 and N2O mixing ratios. In this method, ancient air is extracted from relatively large ice samples (~400 g) with a dry-extraction "ice grater" device. The liberated air is cryogenically purified to a CO2 and N2O mixture and analyzed with a microvolume-equipped dual-inlet IRMS (Thermo MAT 253). The reproducibility of the method, based on replicate analysis of ice core samples, is 0.02‰ for δ13C-CO2 and 2 ppm and 4 ppb for the CO2 and N2O mixing ratios, respectively (1σ pooled standard deviation). Our experiments show that minimizing water vapor pressure in the extraction vessel by housing the grating apparatus in a ultralow-temperature freezer (−60 °C) improves the precision and decreases the experimental blank of the method to −0.07 ± 0.04‰. We describe techniques for accurate calibration of small samples and the application of a mass-spectrometric method based on source fragmentation for reconstructing the N2O history of the atmosphere. The oxygen isotopic composition of CO2 is also investigated, confirming previous observations of oxygen exchange between gaseous CO2 and solid H2O within the ice archive. These data offer a possible constraint on oxygen isotopic fractionation during H2O and CO2 exchange below the H2O bulk melting temperature.
Quantitative infrared absorption cross sections of isoprene for atmospheric measurements
Authors: Brauer C. S. , Blake T. A. , Guenther A. B. , Sharpe S. W. , Sams R. L. , Johnson T. J.
Published: November 2014

Abstract. Isoprene (C5H8, 2-methyl-1,3-butadiene) is a volatile organic compound (VOC) and is one of the primary contributors to annual global VOC emissions. Isoprene is produced primarily by vegetation as well as anthropogenic sources, and its OH- and O3-initiated oxidations are a major source of atmospheric oxygenated organics. Few quantitative infrared studies have been reported for isoprene, limiting the ability to quantify isoprene emissions via remote or in situ infrared detection. We thus report absorption cross sections and integrated band intensities for isoprene in the 600–6500 cm−1 region. The pressure-broadened (1 atmosphere N2) spectra were recorded at 278, 298, and 323 K in a 19.94 cm path-length cell at 0.112 cm−1 resolution, using a Bruker IFS 66v/S Fourier transform infrared (FTIR) spectrometer. Composite spectra are derived from a minimum of seven isoprene sample pressures, each at one of three temperatures, and the number densities are normalized to 296 K and 1 atm.
Characterization and verification of ACAM slit functions for trace gas retrievals during the 2011 DISCOVER-AQ flight campaign
Authors: Liu C. , Liu X. , Kowalewski M. G. , Janz S. J. , González Abad G. , Pickering K. E. , Chance K. , Lamsal L. N.
Published: November 2014

Abstract. The Airborne Compact Atmospheric Mapper (ACAM), an ultraviolet/visible/near-infrared spectrometer, has been flown on board the NASA UC-12 aircraft during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) campaigns to provide remote sensing observations of tropospheric and boundary layer pollutants from its radiance measurements. To improve the trace gas retrieval from ACAM measurements, we perform detailed characterization and verification of ACAM slit functions. The wavelengths and slit functions of ACAM measurements are characterized for the air quality channel (~304–500 nm) through cross-correlation with a high-resolution solar irradiance reference spectrum after necessarily accounting for atmospheric gas absorption and the Ring effect in the calibration process. The derived slit functions, assuming a hybrid combination of asymmetric Gaussian and top-hat slit functions, agree very well with the laboratory-measured slit functions. Comparisons of trace gas retrievals between using derived and measured slit functions demonstrate that the cross-correlation technique can be reliably used to characterize slit functions for trace gas retrievals.
Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin
Authors: Hagens M. , Slomp C. P. , Meysman F. J. R. , Seitaj D. , Harlay J. , Borges A. V. , Middelburg J. J.
Published: November 2014

Abstract. Coastal areas are impacted by multiple natural and anthropogenic processes and experience stronger pH fluctuations than the open ocean. These variations can weaken or intensify the ocean acidification signal induced by increasing atmospheric pCO2. The development of eutrophication-induced hypoxia intensifies coastal acidification, since the CO2 produced during respiration decreases the buffering capacity of the hypoxic bottom water. To assess the combined ecosystem impacts of acidification and hypoxia, we quantified the seasonal variation in pH and oxygen dynamics in the water column of a seasonally stratified coastal basin (Lake Grevelingen, the Netherlands). Monthly water column chemistry measurements were complemented with estimates of primary production and respiration using O2 light-dark incubations, in addition to sediment-water fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TA). The resulting dataset was used to set up a proton budget on a seasonal scale. Temperature-induced seasonal stratification combined with a high community respiration was responsible for the depletion of oxygen in the bottom water in summer. The surface water showed strong seasonal variation in process rates (primary production, CO2 air–sea exchange), but relatively small seasonal pH fluctuations (0.46 units on the total hydrogen ion scale). In contrast, the bottom water showed less seasonality in biogeochemical rates (respiration, sediment–water exchange), but stronger pH fluctuations (0.60 units). This marked difference in pH dynamics could be attributed to a substantial reduction in the acid-base buffering capacity of the hypoxic bottom water in the summer period. Our results highlight the importance of acid-base buffering in the pH dynamics of coastal systems and illustrate the increasing vulnerability of hypoxic, CO2-rich waters to any acidifying process.
Policy support, economic incentives and the adoption of irrigation technology in China
Authors: Cremades R. , Wang J. , Morris J.
Published: November 2014

Abstract. The challenges China faces in terms of water availability in the agricultural sector are exacerbated by the sector's low irrigation efficiency. To increase irrigation efficiency, promoting irrigation technology has been emphasized by policy makers in China. The overall goal of this paper is to understand the effect of policy support and economic incentives on the adoption of irrigation technology in China. Based on a unique dataset collected at household and village levels from seven provinces in China, results indicated that household-based irrigation technology has become noticeable in almost every Chinese village. In contrast, only about half of Chinese villages have adopted community-based irrigation technology. Despite the relatively high adoption level of household-based irrigation technology at the village level, its actual adoption on crop-sown areas was not high, and it was even lower for community-based irrigation technology. The econometric analyses results revealed that policy supports via subsidies and extension services have played an important role in promoting the adoption of irrigation technology. Strikingly, the present irrigation pricing policy has played significant but contradictory roles in promoting the adoption of different types of irrigation technology. Irrigation pricing showed a positive impact on household-based irrigation technology, and a negative impact on community-based irrigation technology, possibly related to their substitution relationship, because having higher adoption of household-based irrigation technology reduce the incentives to invest in community-based irrigation technology. The paper finally concludes and discusses some policy implications.
The impact of aerosol optical depth assimilation on aerosol forecasts and radiative effects during a wild fire event over the United States
Authors: Chen D. , Liu Z. , Schwartz C. S. , Lin H.-C. , Cetola J. D. , Gu Y. , Xue L.
Published: November 2014

Abstract. The Gridpoint Statistical Interpolation three-dimensional variational data assimilation (DA) system coupled with the Weather Research and Forecasting/Chemistry (WRF/Chem) model was utilized to improve aerosol forecasts and study aerosol direct and semi-direct radiative feedbacks during a US wild fire event. Assimilation of MODIS total 550 nm aerosol optical depth (AOD) retrievals clearly improved WRF/Chem forecasts of surface PM2.5 and organic carbon (OC) compared to the corresponding forecasts without aerosol data assimilation. The scattering aerosols in the fire downwind region typically cooled layers both above and below the aerosol layer and suppressed convection and clouds, which led to an average of 2% precipitation decrease during the fire week. This study demonstrated that, even with no input of fire emissions, AOD DA improved the aerosol forecasts and allowed a more realistic model simulation of aerosol radiative effects.
Modelling climate change responses in tropical forests: similar productivity estimates across five models, but different mechanisms and responses
Authors: Rowland L. , Harper A. , Christoffersen B. O. , Galbraith D. R. , Imbuzeiro H. M. A. , Powell T. L. , Doughty C. , Levine N. M. , Malhi Y. , Saleska S. R. , Moorcroft P. R. , Meir P. , Williams M.
Published: November 2014

Abstract. Accurately predicting the response of Amazonia to climate change is important for predicting changes across the globe. However, changes in multiple climatic factors simultaneously may result in complex non-linear responses, which are difficult to predict using vegetation models. Using leaf and canopy scale observations, this study evaluated the capability of five vegetation models (CLM3.5, ED2, JULES, SiB3, and SPA) to simulate the responses of canopy and leaf scale productivity to changes in temperature and drought in an Amazonian forest. The models did not agree as to whether gross primary productivity (GPP) was more sensitive to changes in temperature or precipitation. There was greater model–data consistency in the response of net ecosystem exchange to changes in temperature, than in the response to temperature of leaf area index (LAI), net photosynthesis (An) and stomatal conductance (gs). Modelled canopy scale fluxes are calculated by scaling leaf scale fluxes to LAI, and therefore in this study similarities in modelled ecosystem scale responses to drought and temperature were the result of inconsistent leaf scale and LAI responses among models. Across the models, the response of An to temperature was more closely linked to stomatal behaviour than biochemical processes. Consequently all the models predicted that GPP would be higher if tropical forests were 5 °C colder, closer to the model optima for gs. There was however no model consistency in the response of the An–gs relationship when temperature changes and drought were introduced simultaneously. The inconsistencies in the An–gs relationships amongst models were caused by to non-linear model responses induced by simultaneous drought and temperature change. To improve the reliability of simulations of the response of Amazonian rainforest to climate change the mechanistic underpinnings of vegetation models need more complete validation to improve accuracy and consistency in the scaling of processes from leaf to canopy.
Extreme temperature days and their potential impacts on southern Europe
Authors: Cardil A. , Molina D. M. , Kobziar L. N.
Published: November 2014

Abstract. Extreme-temperature events have consequences for human health and mortality, forest disturbance patterns, agricultural productivity, and the economic repercussions of these consequences combined. To gain insight into whether extreme-temperature events are changing in light of global climate dynamics, the annual numbers of high-temperature days (those with temperatures higher than 20, 22.5, and 25 °C at 850 hPa) were analyzed across southern Europe from the years 1978 to 2012. A significant increase in the frequency of these days was found in many areas over the time period analyzed, and patterns in the spatial distribution of these changes were identified. We discuss the potential consequences of the increases in high-temperature days with regards to forest fire risk, human health, agriculture, energy demands, and some potential economic repercussions.
50-year return-period wet-snow load estimation based on weather station data for overhead line design in France
Authors: Ducloux H. , Nygaard B. E.
Published: November 2014

Abstract. Historically, as far as wet-snow loads were concerned, overhead line design was often based on experience or long-term applications with positive results. New standard like CENELEC EN 50341-1 (2012) take into account characteristic loads, i.e. 50-year return-period loads, for the overhead line design. This article proposes a method to estimate characteristic wet-snow loads based on meteorological data recorded at weather stations. The model used to calculate those loads is mainly inspired by a recent article written by Nygaard et al. (2013a) in which a new parameterization is proposed for the classical cylindrical wet-snow accretion model, as described in ISO 12494 standard (2001), annex C. After a complete description of the model and its parameterization adapted to French wet-snow events, the statistical issues are examined. Then, the model is used with the meteorological data of 87 weather stations in order to calculate wet-snow loads whose relevance has been positively tested according to real damages recorded in a complete wet-snow event database. At last, the characteristic loads of those 87 stations have been determined according to all the loads generated by the model and processed by a peak-over-threshold (POT) method. A practical method to determine the 90% confidence intervals of those characteristic values is given. As it is demonstrated that there is only one value of the ice class (IC) masses proposed by ISO 12494 in each confidence interval, characteristic loads can be easily expressed in terms of ICs. That method shows that ICs ranging from R1 (0.5 kg m−1) to R5 (5 kg m−1) could be used for overhead line design in France.
Regional debris flow susceptibility analysis in mountainous peri-urban areas through morphometric and land cover indicators
Authors: Rogelis M. C. , Werner M.
Published: November 2014

Abstract. A method for assessing regional debris flow susceptibility at the watershed scale, based on an index composed of a morphometric indicator and a land cover indicator, is proposed and applied in 106 peri-urban mountainous watersheds in Bogotá, Colombia. The indicator of debris flow susceptibility is obtained from readily available information common to most peri-urban mountainous areas and can be used to prioritise watersheds that can subsequently be subjected to detailed hazard analysis. Susceptibility is considered to increase with flashiness and the possibility of debris flows occurring. Morphological variables recognised in the literature to significantly influence flashiness and occurrence of debris flows are used to construct the morphometric indicator by applying principal component analysis. Subsequently, this indicator is compared with the results of debris flow propagation to assess its capacity in identifying the morphological conditions of a watershed that make it able to transport debris flows. Propagation of debris flows was carried out using the Modified Single Flow Direction algorithm, following identification of source areas by applying thresholds identified in the slope–area curve of the watersheds. Results show that the morphometric variables can be grouped into four indicators: size, shape, hypsometry and (potential) energy, with energy being the component that best explains the capability of a watershed to transport debris flows. However, the morphometric indicator was found to not sufficiently explain the records of past floods in the study area. Combining the morphometric indicator with land cover indicators improved the agreement and provided a more reliable assessment of debris flow susceptibility in the study area. The analysis shows that, even if morphometric parameters identify a high disposition to the occurrence of debris flow, improving land cover can reduce the susceptibility. However, if favourable morphometric conditions are present but deterioration of the land cover in the watershed takes place, then the susceptibility to debris flow events increases. The indicator of debris flow susceptibility is useful in the identification of flood type, which is a crucial step in flood risk assessment especially in mountainous environments, and it can be used as input for prioritisation of flood risk management strategies at regional level and for the prioritisation and identification of detailed flood hazard analysis. The indicator is regional in scope, and therefore it is not intended to constitute a detailed assessment but to highlight watersheds that could potentially be more susceptible to damaging floods than others in the same region.
On the glacial and interglacial thermohaline circulation and the associated transports of heat and freshwater
Authors: Ballarotta M. , Falahat S. , Brodeau L. , Döös K.
Published: November 2014

Abstract. The thermohaline circulation (THC) and the oceanic heat and freshwater transports are essential for understanding the global climate system. Streamfunctions are widely used in oceanography to represent the THC and estimate the transport of heat and freshwater. In the present study, the regional and global changes of the THC, the transports of heat and freshwater and the timescale of the circulation between the Last Glacial Maximum (LGM, ≈ 21 kyr ago) and the present-day climate are explored using an Ocean General Circulation Model and streamfunctions projected in various coordinate systems. We found that the LGM tropical circulation is about 10% stronger than under modern conditions due to stronger wind stress. Consequently, the maximum tropical transport of heat is about 20% larger during the LGM. In the North Atlantic basin, the large sea-ice extent during the LGM constrains the Gulf Stream to propagate in a more zonal direction, reducing the transport of heat towards high latitudes by almost 50% and reorganising the freshwater transport. The strength of the Atlantic Meridional Overturning Circulation depends strongly on the coordinate system. It varies between 9 and 16 Sv during the LGM, and between 12 to 19 Sv for the present day. Similar to paleo-proxy reconstructions, a large intrusion of saline Antarctic Bottom Water takes place into the Northern Hemisphere basins and squeezes most of the Conveyor Belt circulation into a shallower part of the ocean. These different haline regimes between the glacial and interglacial period are illustrated by the streamfunctions in latitude–salinity coordinates and thermohaline coordinates. From these diagnostics, we found that the LGM Conveyor Belt circulation is driven by an enhanced salinity contrast between the Atlantic and the Pacific basin. The LGM abyssal circulation lifts and makes the Conveyor Belt cell deviate from the abyssal region, resulting in a ventilated upper layer above a deep stagnant layer, and an Atlantic circulation more isolated from the Pacific. An estimate of the timescale of the circulation reveals a sluggish abyssal circulation during the LGM, and a Conveyor Belt circulation that is more vigorous due to the combination of a stronger wind stress and a shortened circulation route.
The efficacy of a “double-D-shaped” wire marker for radiographic measurement of acetabular cup orientation and wear
Authors: Derbyshire Brian , Raut Videshnandan V.
Published: November 2014

Historically, wire markers were attached to cemented all-plastic acetabular cups to demarcate the periphery and to measure socket wear. The wire shape was either a semi-circle passing over the pole of the cup, or a circle around the cup equator. More recently, “double-D” shaped markers were introduced with a part-circular aspect passing over the pole and a semi-circular aspect parallel to the equatorial plane. This configuration enabled cup retroversion to be distinguished from anteversion. In this study, the accuracy of radiographic measurement of cup orientation and wear was assessed for cups with “double-D” and circular markers.

Each cup was attached to a measurement jig which could vary the anteversion/retroversion and internal/ external rotation of the cup. A metal femoral head was fixed within the socket and radiographic images were created for all combinations of cup orientation settings. The images were measured using software with automatic edge detection, and cup orientation and zero-wear accuracies were determined for each setting.

The median error for cup version measurements was similar for both types of wire marker (0.2° double-D marker, −0.24° circular marker), but measurements of the circular marker were more repeatable. The median inclination errors were 2.05° (double-D marker) and 0.23° (circular marker). The median overall “zero wear” errors were 0.19 mm (double-D marker) and 0.03 mm (circular marker). Measurements of the circular wire marker were much more repeatable.
The usage of image trigonometry in bone measurements
Authors: Dymond Ian W. , Ashforth James A. , Dymond Graeme F. , Spirakis Thanos , Learmonth Ian D.
Published: November 2014

The entire musculo-skeletal system responds dynamically to stresses and strains applied to it. Restoring normal biomechanics contributes to the normal function that ensures that physiological stresses and strains are preserved. Appropriate preoperative planning is mandatory to restore normal biomechanics at reconstructive surgery. Effective preoperative planning depends on the ability to reproducibly make accurate measurements of lengths and angles from plain radiographs. Measurement has become an integral part of orthopaedics to define morphological abnormality, to plan for reconstruction and for comparative research. The most prevalent method of measurement is usually based on lines drawn on radiographs with no accurate reference to the actual geometry of the structures. This two-dimensional projection of an asymmetrical three-dimensional structure leads to inaccuracy and consequently to a compromise in the overall precision of many procedures. In addition it is also difficult to monitor the progression of disease as the exact relationship of the bones and joints to each other, and to prosthetics, cannot be accurately recorded. This paper presents a method of digitally measuring relevant bone parameters in a geometric manner in order to achieve accurate, repeatable measurements.
The human hip joint and its long-term load intake – how x-ray density distribution mirrors bone strength
Authors: Hoechel Sebastian , Alder Marc , Wirz Dieter , Müller-Gerbl Magdalena
Published: November 2014

The aim of this study was to gain information about the topographical distribution of the mechanical strength of the subchondral bone plate of the hip joint and evaluate the correlation to its density distribution. Our intention was to describe a method of visualising and monitoring the long-term load intake of the hip using conventional CT-data in a way which might be applied in clinical practice.

We examined the lunate surface of the acetabulum (facies lunata) and femoral head in 25 cases, looking at the density of the subchondral bone plate by computed tomography osteoabsorptiometry (CT-OAM) and determined its mechanical strength by indentation testing using an osteo-penetrometer. The resulting distribution patterns were matched and statistically analysed, showing an inhomogeneous but regular and reproducible distribution of mineralisation and mechanical strength throughout the joint surface. Maximal density was found anterosuperiorly and near the rim of the facies lunata and in the superior area of the femoral head. For each specimen a correlation of density and strength (r2 = 0.77 – 0.97) was found (p<0.01).

The density distribution pattern shown by CT-OAM allows conclusions to be drawn about the distribution of strength and therefore the long term load intake within the subchondral bone plate of the hip. Using conventional CT-data, the method can be used in the clinical setting for evaluation and monitoring.
A comparison of reversed locking compression-distal femoral plates and blade plates in osteotomies for young adult hip pathology
Authors: MacLean Simon B.M. , Evans Scott , O'Hara John N.
Published: November 2014

The aim of this study was to compare fixation of proximal femoral osteotomies using reverse contralateral LCP-Distal Femoral Plates (LCP-DF) with the more traditional blade plate technique.

This was a retrospective review over six years of a single surgeon's practice within a tertiary orthopaedic unit. Patient demographics were collected, along with indication for surgery. Radiological outcomes, fixation failures and the need for revision surgery were recorded. Forty-six patients were identified; 23 patients in the LCP-DF plate group (7 females, 16 males. Mean age 18.3 years old) and 23 patients in the blade plate group (6 females, 17 males. Mean age 19.1 years old).

The patients’ presenting conditions were; 26 Perthes’; eight hip dysplasia; 11 slipped capital femoral epiphysis; one fibrous dysplasia. Osteotomy type included; 13 Double osteotomy, 11 Imhauser; 13 pure valgus; eight valgus + rotation;

There was one revision for implant failure in the LCP-DF group. In the blade plate group, there were four implant failures – three requiring revision operations (p = 0.155). In the LCP-DF group the mean neck-shaft angle difference compared to the contralateral side (if normal) or 135 degrees (if abnormal) was 0.58°. In the condylar plate group the mean difference was 4.37°.

The use of a contralateral LCP-DF plate in the reverse contralateral position to stabilise proximal femoral osteotomies in our cohort confers advantages over blade plate technology. We have found that the plate is stiffer, is easier to use and provides increased screw placement options over standard proximal femoral locking plates.
Successful treatment of isolated, partial thickness ligamentum teres (LT) tears with debridement and capsulorrhaphy
Authors: Amenabar Tomas , O'Donnell John
Published: November 2014

Background

To determine if the addition of anterior capsular tightening to the treatment of partial ligamentum teres (LT) tears by debridement will diminish the recurrence rate of symptoms due to LT retears.

Method

A prospective case series, including all patients treated for an isolated LT tear from June 2009 to August 2011. Arthroscopically the tear was debrided using radiofrequency (RF) and the joint capsule was tightened using either RF or suture plication. All the patients were prospectively assessed with the Modified Harris Hip Score (MHHS) and the Non Arthritic Hip Score (NAHS). A total of 1574 hip arthroscopies were performed from June 2009 to November 2011. Isolated partial LT tears, were found in 27 hips (26 patients). The average age was 24.4 years (range 12-45). There were 24 females and two males.

Results

Over an average follow-up period of 32 months (range 23-49), MHHS and NAHS preoperative outcome scores improved significantly. No revision surgery was required for a recurrent tear.

conclusion

Debridement of partial thickness LT tears, with additional anterior capsule tightening, has been shown to lead to improvents in MHHS and NAHS, with no recurrence of symptoms due to LT retear in the short to medium term.
Trochanteric non-union following revision hip replacement is associated with a poor functional outcome: a matched, case-control study
Authors: Amin Anish K. , Bergman Neil
Published: November 2014

The aim of this study was to determine the functional outcome in patients with a trochanteric non-union following revision total hip replacement. Twenty-five consecutive patients with a unilateral, trochanteric non-union were individually matched for age, sex, body mass index and duration of follow-up to two control groups: 1) 25 patients who had a primary total hip replacement (‘primary controls’); and 2) 25 patients who had a revision total hip replacement (‘revision controls’). At a mean follow up of approximately four years, the Harris hip score (HHS) for the cases was significantly worse compared to the primary control group (p<0.0001) and the revision control group (p<0.0001), with an overall ‘poor’ outcome in over half of the patients. The physical component of the Short Form-12 (SF-12) score was also significantly worse for the cases compared to the primary control group (p = 0.001), while the difference in the mental component approached significance (p = 0.057). There was no difference in the SF-12 scores between the cases and the revision control group (p = 0.1 and p = 0.4, respectively). A non-union of the greater trochanter is associated with a poor functional outcome following revision total hip replacement.
A Pain in the Backside: A Case Report of Coxa Saltans Occurring at the Proximal Hamstring Origin
Authors: Shur Natalie , Dandachli Wael , Findlay Iain , Beech Zine , Bankes Marcus J. K.
Published: November 2014

Coxa saltans occurring at the proximal hamstring origin has been rarely reported in the literature. It is better known as occurring at the iliotibial band or the iliopsoas tendon. We report a case of coxa saltans due to subluxation of the origin of the long head of biceps femoris tendon at the ischial tuberosity. This was successfully treated using a mini-open surgical technique. Six weeks postoperatively, the snapping and the associated pain were abolished and the patient was able to resume their participation in athletic activities.
Gait Metric Profile and Gender Differences in Hip Osteoarthritis Patients. A Case-Controlled Study
Authors: Khashan Morsi , Mor Amit , Beer Yiftah , Rath Ehud , Morgensteren David R. , Debi Ronen , Elbaz Avi
Published: November 2014

Purpose

Hip osteoarthritis (OA) is a slowly progressive destructive disease that results in alterations in joint loads and biomechanics to which patients adapt compensatory alterations and abnormal gait patterns. This prospective cross-sectional, case-controlled study examined these alterations in gait metrics and evaluated gender differences in gait spatiotemporal parameters. Correlations between function and gait metrics were also investigated.

Basic Procedures

Hip OA patients (138 females and 122 males) and healthy controls (14 females and 26 males) matched for age and gender underwent the same investigative protocol consisting of a spatiotemporal gait analysis followed by functional evaluations using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the SF-36 Health Survey (SF-36).

Main Findings

Differences between the patient and the control groups were significant in all the spatiotemporal parameters. There were significant gender differences within the hip OA group in all parameters except for cadence and single limb support percentage. WOMAC and SF-36 scores revealed significant differences between the study and control groups in most components. Significantly higher scores in the three components of the WOMAC as well as in six SF-36 score components were found among males compared to females in the patient group.

Principal Conclusions

Gait, WOMAC and SF-36 were effective objective and subjective tools for evaluating a large cohort of patients with hip OA, and can be highly useful for supplementing the assessment of hip OA severity and enhancing treatment efficacy during the course of the disease.
Hypothermia and Low Body Temperature are Common and Associated with High Mortality in Hip Fracture Patients
Authors: Uzoigwe Chika E. , Khan Asif , Smith Robert P. , Venkatesan Murali , Balasubramanian Sivaraman , Isaac Sherif , Chami George
Published: November 2014

Hip fractures remain one of the commonest injuries treated by orthopaedic surgeons. Despite recent initiatives, the fracture engenders a very high mortality. The UK National Hip Fracture Database reports a 30-day mortality of 8%. The pathophysiology that results in such high mortality remains imperfectly understood. The significance of thermal dysregulation in polytrauma is becoming increasingly recognised. Hypothermia is a common feature of polytrauma and is associated with adverse outcomes. No previous studies have explored the prevalence and outcomes of hip fracture patients with hypothermia and/or low body temperature. We sought to evaluate this.

We prospectively collected the demographic details and admission tympanic temperature of all patients presenting to our institution with hip fracture. Patient mortality was also recorded.

Seven hundred and eighty-one patients were included. The mean age was 80 years. 38% (300) had a temperature below 36.5°C. 4% (30) presented with a tympanic temperature greater than 37.5°C. The 30-day mortality for patients with a normal admission temperature (between 36.5° and 37.5°C) was 5.1%. This value was 15.3% for those whose admission temperature was less than 36.5°C (p<0.0001). Correcting for potential confounders of age and gender, those with an admission temperature of less than 36.5°C had a 2.8 fold increase in the odds of mortality at 30-days compared with those with an admission temperature of between 36.5° and 37.5°C (p<0.0005).

Low body temperature is strongly linked to 30-day mortality in hip fracture patients.
Effect of Home Grinding on Properties of Brewed Coffee
Authors: Murray Christopher , Laredo Thamara
Published: November 2014

We present measurements of particle size distribution, density, loss of coffee on brewing and caffeine content in brewed coffee (as measured using Fourier Transform Infrared Spectroscopy) as a function of grinding time using a blade-type grinder. In general, there is not a lack of correlation between coffee properties and grinding for grinding times in excess of 42 s, but mass loss on brewing and caffeine content are both increased with grinding times between 0 and 42 s. In addition, we present evidence that this dependence of the composition of brewed coffee on grinding time is a function of increased coffee particle surface area that results from grinding, rather than increased loss of grounds into the brewed beverage or increased percolation time. Finally, we present a general recommendation for determining equivalency between small amounts of finely ground coffee and larger amounts of coarser-ground coffee.
Determination of potential glacial refugia and possible migration routes of Campylocentrum (Vandeae, Orchidaceae) species through the Darién Gap
Authors: Kolanowska Marta
Published: November 2014

The possible glacial refugia of four Campylocentrum species reported from the Darién Gap are estimated based on the ecological niche modeling. The potential migration routes of the studied species are presented. The current ranges of all species designated based on the available floristic data are compared with their potential habitats distribution.
Transcription mediated insulation and interference direct gene cluster expression switches
Authors: Nguyen Tania , Fischl Harry , Howe Françoise S , Woloszczuk Ronja , Serra Barros Ana , Xu Zhenyu , Brown David , Murray Struan C , Haenni Simon , Halstead James M , O'Connor Leigh , Shipkovenska Gergana , Steinmetz Lars M , Mellor Jane
Published: November 2014

In yeast, many tandemly arranged genes show peak expression in different phases of the metabolic cycle (YMC) or in different carbon sources, indicative of regulation by a bi-modal switch, but it is not clear how these switches are controlled. Using native elongating transcript analysis (NET-seq), we show that transcription itself is a component of bi-modal switches, facilitating reciprocal expression in gene clusters. HMS2, encoding a growth-regulated transcription factor, switches between sense- or antisense-dominant states that also coordinate up- and down-regulation of transcription at neighbouring genes. Engineering HMS2 reveals alternative mono-, di- or tri-cistronic and antisense transcription units (TUs), using different promoter and terminator combinations, that underlie state-switching. Promoters or terminators are excluded from functional TUs by read-through transcriptional interference, while antisense TUs insulate downstream genes from interference. We propose that the balance of transcriptional insulation and interference at gene clusters facilitates gene expression switches during intracellular and extracellular environmental change.
Synaptic plasticity and cognitive function are disrupted in the absence of Lrp4
Authors: Gomez Andrea M , Froemke Robert C , Burden Steven J
Published: November 2014

Lrp4, the muscle receptor for neuronal Agrin, is expressed in the hippocampus and areas involved in cognition. The function of Lrp4 in the brain, however, is unknown, as Lrp4−/− mice fail to form neuromuscular synapses and die at birth. Lrp4−/− mice, rescued for Lrp4 expression selectively in muscle, survive into adulthood and showed profound deficits in cognitive tasks that assess learning and memory. To learn whether synapses form and function aberrantly, we used electrophysiological and anatomical methods to study hippocampal CA3–CA1 synapses. In the absence of Lrp4, the organization of the hippocampus appeared normal, but the frequency of spontaneous release events and spine density on primary apical dendrites were reduced. CA3 input was unable to adequately depolarize CA1 neurons to induce long-term potentiation. Our studies demonstrate a role for Lrp4 in hippocampal function and suggest that patients with mutations in Lrp4 or auto-antibodies to Lrp4 should be evaluated for neurological deficits.
Epigenetic modulation of type-1 diabetes via a dual effect on pancreatic macrophages and β cells
Authors: Fu Wenxian , Farache Julia , Clardy Susan M , Hattori Kimie , Mander Palwinder , Lee Kevin , Rioja Inmaculada , Weissleder Ralph , Prinjha Rab K , Benoist Christophe , Mathis Diane
Published: November 2014

Epigenetic modifiers are an emerging class of anti-tumor drugs, potent in multiple cancer contexts. Their effect on spontaneously developing autoimmune diseases has been little explored. We report that a short treatment with I-BET151, a small-molecule inhibitor of a family of bromodomain-containing transcriptional regulators, irreversibly suppressed development of type-1 diabetes in NOD mice. The inhibitor could prevent or clear insulitis, but had minimal influence on the transcriptomes of infiltrating and circulating T cells. Rather, it induced pancreatic macrophages to adopt an anti-inflammatory phenotype, impacting the NF-κB pathway in particular. I-BET151 also elicited regeneration of islet β-cells, inducing proliferation and expression of genes encoding transcription factors key to β-cell differentiation/function. The effect on β cells did not require T cell infiltration of the islets. Thus, treatment with I-BET151 achieves a ‘combination therapy’ currently advocated by many diabetes investigators, operating by a novel mechanism that coincidentally dampens islet inflammation and enhances β-cell regeneration.
Making connections
Authors: Kenney Justin W , Frankland Paul W
Published: November 2014

Deleting a gene called Sema5A, which has been linked to autism in humans, causes neurons to form more connections in mice, and also alters how these mutant mice interact with other mice.
Extratropical cyclones in a warmer, moister climate: A recent Atlantic analogue
Authors: Li Muxingzi , Woollings Tim , Hodges Kevin , Masato Giacomo
Published: November 2014

Current climate model projections do not exhibit a large change in the intensity of extratropical cyclones. However, there are concerns that current models represent moist processes poorly, and this provides motivation for investigating observational evidence for how cyclones behave in warmer climates. In the North Atlantic in particular, recent decades provide a clear contrast between warm and cold climates due to Atlantic Multidecadal Variability. In this paper we investigate these periods as analogues which may provide a guide to future cyclone behavior. While temperature and moisture rise in recent warm periods as in the projections, differences in energetics and temperature gradients imply that these periods are only partial analogues. The main result from current reanalyses is that while increased cyclone‐associated precipitation is seen in the recent warm periods, there is no robust evidence of an increase in cyclone intensity by other measures, such as maximum wind speed or vorticity. A set of low‐ and high‐resolution model simulations are also studied, suggesting that changes in cyclone intensity may be different in higher‐resolution reanalyses.