bluuebunny/crossref_metadata_2025 huggingface dataset:
INFLUENCE OF VARIOUS DAILY TASKS ON SEGMENTED TRUNK KINEMATICS
Authors: Breloff Scott P. , Chou Li-Shan
Published: February 2016

Back pain can affect up to 65% of the American population and cost the health care system approximately fifty billion dollars each year. Due to the difficulty with recording spine/trunk movement, several methods and models exist. The myriad of methods and the need for understanding of spine/trunk motion has led to a lack in a ‘gold-standard’ of treatment for individuals with back pain. Therefore, the purpose of this study was to examine the effect of different activities of daily living on the kinematics of individual trunk segments in young adults to determine how common ambulatory tasks will alter trunk motion compared to level walking.

Young healthy adults completed, in a random order, four activities of daily living: level walking, obstacle crossing, stair ascent and descent using a previously validated model. Subjects were outfitted with a full body marker set which included a segmented trunk. Multi-segmented trunk angles between the three inferior segments, sacrum to lower lumbar [SLL], lower lumbar to upper lumbar [LLUL] and upper lumbar to lower thorax [ULLT], were calculated and compared between tasks. Peak flexion angles, instance of peak angle and range of motion were analyzed.

The overall hypothesis that different spine levels will have altered kinematics during various activities of daily living was supported. Stair descent had smaller peak flexion angles than obstacle crossing and stair ascent. The instance of peak angle were different depending on trunk angle and daily task. The most inferior trunk angle — Sacrum-to-Lower Lumbar — had the largest range of motion during all four tasks in all three (sagittal, frontal and transverse) planes of motion.

This study was able to show how various activities of daily living produce different motions in the three inferior segments of a multi-segmented trunk method. The results of this study are the first steps in understanding how the trunk responds on a daily basis and how those responses could lead to back pain.
Sylvian fissure epidermoid cyst presenting with intention tremor
Authors: Shah Abhidha , Makkiyah Feda , Goel Atul
Published: February 2016

Epidermoid tumors are benign tumors which contain keratin, cellular debris, and cholesterol, and are lined with stratified squamous epithelium. They grow in discreet silence sustained over a multitude of years. The tumors most commonly present with headache and seizures. We report the case of a 24-year-old male with a large sylvian fissure epidermoid tumor who presented with intention tremor. The patient was operated, and a near-total excision of the tumor was performed with a resolution of the tremor.
Selective dorsal rhizotomy: A multidisciplinary approach to treating spastic diplegia
Authors: Abou Al-Shaar Hussam , Imtiaz Muhammad , Alhalabi Hazem , Alsubaie Shara , Sabbagh Abdulrahman
Published: February 2016

Background: Spasticity is a motor disorder that interferes with mobility and affects the quality of life. Different approaches have been utilized to address patients with spastic diplegia, among which is selective dorsal rhizotomy (SDR). Although SDR has been shown to be efficacious in treating spastic patients, many neurologists and neurosurgeons are not well aware of the procedure, its indications, and expected outcomes due to the limited number of centers performing this procedure. Objectives: The aim of this study is to describe the collaborative multidisciplinary approach between neurosurgeons, neurophysiologists, and physiotherapists in performing SDR. In addition, we delineate three illustrative cases in which SDR was performed in our patients. Materials and Methods: A retrospective review and analysis of the clinical records of our three patients who underwent SDR was conducted and reported. Patients' outcomes were evaluated and compared to preoperative measurements based on clinical examination of power, tone (Ashworth scale), gait, and range of motion, as well as subjective functional assessment, gross motor function classification system, and gross motor function measure with follow-up at 6, 12, and 24 months postoperatively. A detailed description of our neurosurgical technique in performing SDR in collaboration with neurophysiology and physiotherapy monitoring is provided. Results: The three patients who underwent SDR using our multidisciplinary approach improved both functionally and objectively after the procedure. No intraoperative or postoperative complications were encountered. All patients were doing well over a long postoperative follow-up period. Conclusion: A multidisciplinary approach to treating spastic diplegia with SDR can provide good short-term and long-term outcomes in select patients suffering from spastic diplegia.
Computed tomographic study of posterior cranial fossa, foramen magnum, and its surgical implications in Chiari malformations
Authors: Iqbal Showkathali , Robert Ambooken , Mathew Dominic
Published: February 2016

Objective: The aim of this study is to measure the height and volume of the bony part of the posterior cranial fossa (PCF) and the surface area of the foramen magnum (FM) using computed tomography (CT) scans and to correlate our clinical findings with the available current literature. Materials and Methods: This cross-sectional study was conducted in a tertiary care referral hospital in the Southern part of India during the period from January 2015 to August 2015. A total of 100 CT scans of the suspected head injury patients were collected retrospectively form the basis for this study. The height, volume of PCF and the anteroposterior (AP), transverse diameter, and surface area of the FM were measured. The values of all parameters were subjected to statistical analysis using SPSS version 16. Results: The age of the patients were ranged between 18 and 70 years with the mean age of 41.22 ± 13.93 years. The dimensions of the posterior fossa and FM were larger in males compared to females. The mean height of the posterior fossa was 38.08 (±4.718) mm (P = 0.0001), and the mean volume of the posterior fossa was 157.23 (±6.700) mm3 (P = 0.0001). The mean AP, transverse diameter, and the surface area of the FM were 33.13 (± 3.286) mm, 29.01 (± 3.081) mm, and 763.803 (±138.276) mm2, respectively. Conclusion: The normal dimensions of the posterior fossa and FM were less in females than males and were useful to radiologists and neurosurgeons to better their diagnostic inferences, as well as to determine the proper treatment options in Chiari malformation type I (CMI) and other posterior fossa anomalies. The posterior fossa tissue volume can be reliably measured in patients with CMI using our method. More studies were required because there were variations in dimensions among individuals of different races in different regions of the world.
Utility and challenges in intraoperative consultation of spinal lesions by crush smear cytology
Authors: Dikondwar Aparna , Dani Aarti , Gaikwad Saroj , Tathe Shilpa , Randale Archana , Chawhan Sanjay , Kumbhalkar Dinkar
Published: February 2016

Background: Various methods are used for intraoperative consultation of spinal lesions. Crush smear cytology is one such method that is accurate, rapid, and allows preservation of tissue for paraffin-embedded sections. Aims: To study the cytomorphology of various neoplastic and nonneoplastic lesions involving and compressing the spinal cord. To evaluate accuracy and discuss diagnostic pitfalls of crush smear cytology. Materials and Methods: Over a period of 5 years (January 2008 to October 2012), a total of 57 spinal lesions were referred for intraoperative cytology. In four cases, material was inadequate for evaluation, so we analyzed 53 cases. Results: Majority of lesions were neoplastic accounting for 86.79% whereas nonneoplastic lesions constituted 13.20%. Most of the tumors were low grade (82.92%). Overall accuracy rate was 90.56% with accuracy of 91.30% and 85.71% for neoplastic and inflammatory lesions, respectively. Conclusion: Crush smear technique is a simple, reliable, easy, and rapid method for diagnosing neoplastic and inflammatory lesions involving and compressing the spinal cord. It gives an immediate idea of prognosis so that surgeon can modify the operative procedure, if necessary.
Wall-to-lumen ratio of intracranial arteries measured by indocyanine green angiography
Authors: Nakagawa Daichi , Shojima Masaaki , Yoshino Masanori , Kin Taichi , Imai Hideaki , Nomura Seiji , Saito Toki , Nakatomi Hirofumi , Oyama Hiroshi , Saito Nobuhito
Published: February 2016

Background: The wall-to-lumen ratio (WLR) is an important parameter in vascular medicine because it indicates the character of vascular wall as well as the degree of stenosis. Despite the advances in medical imaging technologies, it is still difficult to measure the thin-walled normal intracranial arteries, and the reports on the WLR of normal intracranial artery are limited. It might be possible to calculate the WLR using the indocyanine green (ICG) angiography, which is used to observe intracranial vessels during microsurgery.
Purpose: To evaluate the WLR of normal intracranial arteries using ICG angiography. Materials and Methods: From the three cases in which ICG angiography was recorded with a ruler during microsurgery, 20 measurement points were chosen for the analysis. The ICG was injected intravenously with a dose of 0.2 mg/kg, and the vessels were inspected at high magnification using an operating microscope equipped with near-infrared illumination system. The vessel outer diameter and the luminal diameter were measured using the images before and after the ICG arrival based on the pixel ratio method using a ruler as reference, respectively. The WLR was calculated as 0.5 × (vessel outer diameter − vessel luminal diameter). Results: The WLR (mean ± standard deviation) of normal intracranial arteries was 0.086 ± 0.022. The WLR tended to be high in small arteries. Conclusion: The WLR of normal intracranial arteries calculated using ICG angiography was consistent with the WLR reported in the previous reports based on human autopsy.
Outcome of laminoplasty in cervical spinal cord injury with stable spine
Authors: Ghasemi Amir , Behfar Behshad
Published: February 2016

Background and Objective: Cervical spinal cord injury (CSCI) with a stable spine has been increasing as the elderly population is dramatically increasing all over the world. In this study, we evaluated the neurological outcome of decompression surgery (laminoplasty) for these patients. Materials and Methods: Forty-one patients with CSCI with stable spine who underwent decompression surgery (laminoplasty) were retrospectively studied. Inclusion criteria were as follows: CSCI without instability, spinal cord contusion in magnetic resonance image (MRI), spinal cord compression rate more than 20%, neurologic deficit American Spinal Cord Injury Association ([ASIA] scale from A to D), and follow-up of at least 12 months. Preoperative neurological state, clinical outcome, and neurological function were measured using the ASIA impairment scale, Japanese Orthopaedic Association (JOA) grading scale, and Hirabayashi recovering rate, respectively. Results: Thirty-three (80.4%) patients showed improvement in ASIA grade at 12-month follow-up. Four (9.7%) patients in ASIA Grade A and 4 (9.7%) patients in ASIA Grade D remain unchanged. The mean JOA score improved from 8.4 ± 6.1 points preoperatively to 11.2 ± 5.4 points at 12 months postoperatively. Improvement in JOA was statistically significant (P < 0.05). The mean Hirabayashi recovery rate was 37.4 ± 25.3%. Conclusion: Surgical decompression (laminoplasty) is helpful in relieving cord compromise and neurological deficit in CSCI with stable spine.
The effect of stents in cerebral aneurysms: A review
Authors: Alkhalili Kenan , Hannallah Jack , Cobb Mary , Chalouhi Nohra , Philips Jessica , Echeverria Angela , Jabbour Pascal , Babiker M , Frakes David , Gonzalez L
Published: February 2016

The etiology of up to 95% of cerebral aneurysms may be accounted for by hemodynamically-induced factors that create vascular injury. The purpose of this review is to describe key physical properties that stents have and how they affect cerebral aneurysms. We performed a two-step screening process . First, a structured search was performed using the PubMed database. The following search terms and keywords were used: “Hemodynamics,” “wall shear stress (WSS),” “velocity,” “viscosity,” “cerebral aneurysm,” “intracranial aneurysm,” “stent,” “flow diverter,” “stent porosity,” “stent geometry,” “stent configuration,” and “stent design.” Reports were considered if they included original data, discussed hemodynamic changes after stent-based treatment of cerebral aneurysms, examined the hemodynamic effects of stent deployment, and/or described the geometric characteristics of both stents and the aneurysms they were used to treat. The search strategy yielded a total of 122 articles, 61 were excluded after screening the titles and abstracts. Additional articles were then identified by cross-checking reference lists. The final collection of 97 articles demonstrates that the geometric characteristics and configurations of deployed stents influenced hemodynamic parameters such as aneurysmal WSS, inflow, and pressure. The geometric characteristics of the aneurysm and its position also had significant influences on intra-aneurysmal hemodynamics after treatment. In conclusion, changes in specific aneurysmal hemodynamic parameters that result from stenting relate to a number of factors including the geometric properties and configurations of deployed stents, the geometric properties of the aneurysm, and the pretreatment hemodynamics.
Dysembryoplastic neuroepithelial tumor: A rare brain tumor not to be misdiagnosed
Authors: Sukheeja Deepti , Mehta Jayanti
Published: February 2016

Dysembryoplastic neuroepithelial tumor (DNET) is a recently described, morphologically unique, and surgically curable low-grade brain tumor which is included in the latest WHO classification as neuronal and mixed neuronal-glial tumor. It is usually seen in children and young adults. The importance of this particular entity is that it is a surgically curable neuroepithelial neoplasm. When recognized, the need for adjuvant radiotherapy and chemotherapy is obviated. We hereby present a case report of an 8-year-old male child who presented with intractable seizures and parieto-occipital space occupying lesion. Histologically, the tumor exhibited features of WHO grade I dysembryoplastic neuroepithelial tumor which was further confirmed by immunohistochemistry.
Safety and efficacy of spinal loop rectangle and sublaminar wires for osteoporotic vertebral compression fracture fixation
Authors: Patil Sanganagouda , Bhojaraj Shekhar , Nene Abhay
Published: February 2016

Background: Natural history of osteoporotic vertebral compression fractures (OVCFs), that is, collapse, loads the rigid pedicle screw rod construct in the absence of anterior column reconstruction, often leading to implant back outs. Semi rigid spinal loop rectangle and sublaminar wire construct allows controlled axial collapse and does not require anterior column reconstruction. Materials and Methods: This is a retrospective study of 50 consecutive patients of OVCFs. The immediate and final follow-up safety (neurologic deficit, implant failure/back out, revision surgeries, and infection) and efficacy (visual analog scale [VAS] score, axial collapse of the fracture, fracture union and retaining, and the attempted segmental deformity correction) parameters were compared to describe the utility of spinal loop rectangle and sublaminar wiring as a novel, low cost modality of spinal instrumentation for treating OVCFs. Results: All the twelve patients with Frankel grade D neurologic deficit improved to Frankel grade E and six patients (out of 8) with Frankel grade C improved to Frankel grade E (and remaining two patients improved to Frankel grade D), following surgery. The average preoperative VAS score of 8.98 (ranging from 5 to 10) improved to 2.76 (ranging from 1 to 10) at final follow-up. Controlled collapse of anterior column, union of OVCF nonunion, and retaining of attempted deformity correction by sublaminar wire anchors cephalad and caudal to the transpedicular decompression was seen in each patient at the final follow-up. Conclusion: Spinal loop rectangle and sublaminar wiring construct are viable alternative options for stabilizing OVCFs.
Green Tea Leaves as a Natural Adsorbent for the Removal of Cr(VI) from Aqueous Solutions
Authors: Jeyaseelan Christine , Gupta Astha
Published: February 2016

Chromium(VI) has been found to be one of the toxic metals present in water obtained from industrial effluents. This study deals with the removal of Cr(VI) using used green tea leaves, which is a waste material. The sorption of Cr(VI) was carried out by using a batch method, and its concentration was determined using an ultraviolet visible spectrophotometer at 540 nm. Parameters such as pH, mass of adsorbate, concentration of adsorbent, time of contact, and temperature were optimized. It was observed that, under optimum conditions, the percentage efficiency of removal of Cr(VI) was up to 99%. Adsorption studies were carried out using Langmuir and Freundlich adsorption isotherms. The values of Δ G, Δ H, and Δ S were also calculated, which showed that the process is spontaneous and the extent of adsorption decreases with the increase in temperature. The kinetic studies were carried out, and it was found that the reactions followed pseudo-second-order kinetics. This technique can be used for the removal of Cr(VI) from water obtained from industries, which have chromium as one of the main pollutants in their effluents.
Potential Role of Omega-3 Fatty Acids on the Myogenic Program of Satellite Cells
Authors: Bhullar Amritpal S. , Putman Charles T. , Mazurak Vera C.
Published: February 2016

Skeletal muscle loss is associated with aging as well as pathological conditions. Satellite cells (SCs) play an important role in muscle regeneration. Omega-3 fatty acids are widely studied in a variety of muscle wasting diseases; however, little is known about their impact on skeletal muscle regeneration. The aim of this review is to evaluate studies examining the effect of omega-3 fatty acids, α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid on the regulation of SC proliferation and differentiation. This review highlights mechanisms by which omega-3 fatty acids may modulate the myogenic program of the stem cell population within skeletal muscles and identifies considerations for future studies. It is proposed that minimally three myogenic transcriptional regulatory factors, paired box 7 (Pax7), myogenic differentiation 1 protein, and myogenin, should be measured to confirm the stage of SCs within the myogenic program affected by omega-3 fatty acids.
High-resolution inventory of ammonia emissions from agricultural fertilizer in China from 1978 to 2008
Authors: Xu P. , Liao Y. J. , Lin Y. H. , Zhao C. X. , Yan C. H. , Cao M. N. , Wang G. S. , Luan S. J.
Published: February 2016

Abstract. The quantification of ammonia (NH3) emissions is essential to the more accurate quantification of atmospheric nitrogen deposition, improved air quality and the assessment of ammonia-related agricultural policy and climate mitigation strategies. The quantity, geographic distribution and historical trends of these emissions remain largely uncertain. In this paper, a new Chinese agricultural fertilizer NH3 (CAF_NH3) emissions inventory has been compiled that exhibits the following improvements: (1) a 1  ×  1 km gridded map on the county level was developed for 2008; (2) a combined bottom-up and top-down method was used for the local correction of emission factors (EFs) and parameters; (3) the temporal patterns of historical time trends for 1978–2008 were estimated and the uncertainties were quantified for the inventories; and (4) a sensitivity test was performed in which a province-level disaggregated map was compared with CAF_NH3 emissions for 2008. The total CAF_NH3 emissions for 2008 were 8.4 TgNH3 yr−1 (a 6.6–9.8 Tg interquartile range). From 1978 to 2008, annual NH3 emissions fluctuated with three peaks (1987, 1996 and 2005), and total emissions increased from 3.2 to 8.4 Tg at an annual rate of 3.0 %. During the study period, the contribution of livestock manure spreading increased from 37.0 to 45.5 % because of changing fertilization practices and the rapid increase in egg, milk, and meat consumption. The average contribution of synthetic fertilizer, which has a positive effect on crop yields, was approximately 38.3 % (minimum: 33.4 %; maximum: 42.7 %). With rapid urbanization causing a decline in the rural population, the contribution of the rural excrement sector varied widely between 20.3 % and 8.5 %. The average contributions of cake fertilizer and straw returning were approximately 3.8 and 4.5 %, respectively, thus small and stable. Collectively, the CAF_NH3 emissions reflect the nation's agricultural policy to a certain extent. An effective approach to decreasing PM2.5 concentrations in China would be to simultaneously decrease NOx, SO2, and NH3 emissions.
Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols
Authors: Riedel T. P. , Lin Y.-H. , Zhang Z. , Chu K. , Thornton J. A. , Vizuete W. , Gold A. , Surratt J. D.
Published: February 2016

Abstract. Isomeric epoxydiols from isoprene photooxidation (IEPOX) have been shown to produce substantial amounts of secondary organic aerosol (SOA) mass and are therefore considered a major isoprene-derived SOA precursor. Heterogeneous reactions of IEPOX on atmospheric aerosols form various aerosol-phase components or "tracers" that contribute to the SOA mass burden. A limited number of the reaction rate constants for these acid-catalyzed aqueous-phase tracer formation reactions have been constrained through bulk laboratory measurements. We have designed a chemical box model with multiple experimental constraints to explicitly simulate gas- and aqueous-phase reactions during chamber experiments of SOA growth from IEPOX uptake onto acidic sulfate aerosol. The model is constrained by measurements of the IEPOX reactive uptake coefficient, IEPOX and aerosol chamber wall losses, chamber-measured aerosol mass and surface area concentrations, aerosol thermodynamic model calculations, and offline filter-based measurements of SOA tracers. By requiring the model output to match the SOA growth and offline filter measurements collected during the chamber experiments, we derive estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions.
Evaluation of VIIRS, GOCI, and MODIS Collection 6 AOD retrievals against ground sunphotometer observations over East Asia
Authors: Xiao Q. , Zhang H. , Choi M. , Li S. , Kondragunta S. , Kim J. , Holben B. , Levy R. C. , Liu Y.
Published: February 2016

Abstract. Persistent high aerosol loadings together with extremely high population densities have raised serious air quality and public health concerns in many urban centers in East Asia. However, ground-based air quality monitoring is relatively limited in this area. Recently, satellite-retrieved Aerosol Optical Depth (AOD) at high resolution has become a powerful tool to characterize aerosol patterns in space and time. Using ground AOD observations from the Aerosol Robotic Network (AERONET) and the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-Asia Campaign, as well as from handheld sunphotometers, we evaluated emerging aerosol products from the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (S-NPP), the Geostationary Ocean Color Imager (GOCI) aboard the Communication, Ocean, and Meteorology Satellite (COMS), and Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) (Collection 6) in East Asia in 2012 and 2013. In the case study in Beijing, when compared with AOD observations from handheld sunphotometers, 51 % of VIIRS Environmental Data Record (EDR) AOD, 37 % of GOCI AOD, 33 % of VIIRS Intermediate Product (IP) AOD, 26 % of Terra MODIS C6 3 km AOD, and 16 % of Aqua MODIS C6 3 km AOD fell within the reference expected error (EE) envelope (±0.05 ± 0.15 AOD). Comparing against AERONET AOD over the Japan–South Korea region, 64 % of EDR, 37 % of IP, 61 % of GOCI, 39 % of Terra MODIS, and 56 % of Aqua MODIS C6 3 km AOD fell within the EE. In general, satellite aerosol products performed better in tracking the day-to-day variability than tracking the spatial variability at high resolutions. The VIIRS EDR and GOCI products provided the most accurate AOD retrievals, while VIIRS IP and MODIS C6 3 km products had positive biases.
Gravity-wave effects on tracer gases and stratospheric aerosol concentrations during the 2013 ChArMEx campaign
Authors: Chane Ming Fabrice , Vignelles Damien , Jegou Fabrice , Berthet Gwenael , Renard Jean-Batiste , Gheusi François , Kuleshov Yuriy
Published: February 2016

Abstract. Coupled balloon-borne observations of Light Optical Aerosol Counter (LOAC), M10 meteorological global positioning system (GPS) sondes, ozonesondes and GPS radio occultation data, are examined to identify gravity-wave (GW) induced fluctuations on tracer gases and on the vertical distribution of stratospheric aerosol concentrations during the 2013 ChArMEx (Chemistry-Aerosol Mediterranean Experiment) campaign. Observations reveal signatures of GWs with short vertical wavelengths less than 4 km in dynamical parameters and tracer constituents which are also correlated with the presence of thin layers of strong local enhancements of aerosol concentrations in the upper troposphere and the lower stratosphere. In particular, this is evident from a case study above Ile du Levant (43.02 °N, 6.46 °E) on 26–29 July 2013. Observations show a strong activity of dominant mesoscale inertia GWs with horizontal and vertical wavelengths of 370–510 km and 2–3 km respectively, and periods of 10–13 h propagating southward at altitudes of 13–20 km and eastward above 20 km during 27–28 July which is also captured by the European Center for Medium range Weather Forecasting (ECMWF) analyses. Ray-tracing experiments indicate the jet-front system to be the source of observed GWs. Simulated vertical profiles of dynamical parameters with large stratospheric vertical wind maximum oscillations ± 40 mms−1 are produced for the dominant mesoscale GW using the simplified linear GW theory. Parcel advection method reveals signatures of GWs in the ozone mixing ratio and the specific humidity. Simulated vertical wind perturbations of the dominant GW and small-scale perturbations of aerosol concentration (aerosol size of 0.2–0.7 μm) are in phase in the lower stratosphere. Present results support the importance of vertical wind perturbations in the GW-aerosol relation. The observed mesoscale GW induces a strong modulation of the amplitude of tracer gases and the stratospheric aerosol background.
Global combustion sources of organic aerosols: Model comparison with 84 AMS factor analysis data sets
Authors: Tsimpidi A. P. , Karydis V. A. , Pandis S. N. , Lelieveld J.
Published: February 2016

Abstract. Emissions of organic compounds from biomass, biofuel and fossil fuel combustion strongly influence the global atmospheric aerosol load. Some of the organics are directly released as primary organic aerosol (POA). Most are emitted in the gas phase and undergo chemical transformations (i.e., oxidation by hydroxyl radical) and form secondary organic aerosol (SOA). In this work we use the global chemistry climate model EMAC with a computationally efficient module for the description of organic aerosol (OA) composition and evolution in the atmosphere (ORACLE). The tropospheric burden of open biomass and anthropogenic (fossil and biofuel) combustion particles is estimated to be 0.59 Tg and 0.63 Tg, respectively, accounting for about 30 % and 32 % of the total tropospheric OA load. About 30 % of the open biomass burning and 10 % of the anthropogenic combustion aerosols originate from direct particle emissions while the rest is formed in the atmosphere. A comprehensive dataset of aerosol mass spectrometer (AMS) measurements along with factor-analysis results from 84 field campaigns across the Northern Hemisphere are used to evaluate the model results. Both the AMS observations and the model results suggest that over urban areas both POA (25–40 %) and SOA (60–75 %) contribute substantially to the overall OA mass while further downwind and in rural areas the POA concentrations decrease substantially and SOA dominates (80–85 %). EMAC does a reasonable job in reproducing POA and SOA levels during most of the year. However, it tends to underpredict POA and SOA concentrations during winter indicating that the model misses a wintertime source of OA (e.g., residential biofuel use) and a SOA formation pathway (e.g., multiphase oxidation).
Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010
Authors: Pandey S. , Houweling S. , Krol M. , Aben I. , Chevallier F. , Dlugokencky E. J. , Gatti L. V. , Gloor M. , Miller J. B. , Detmers R. , Machida T. , Röckmann T.
Published: February 2016

Abstract. This study investigates the constraint provided by greenhouse gas measurements from space on surface fluxes. Imperfect knowledge of the light path through the atmosphere, arising from scattering by clouds and aerosols, can heavily bias column measurements retrieved from space. To minimize the impact of such biases, ratios of total column retrieved CH4 and CO2 (Xratio) have been used. We apply the ratio inversion method described in Pandey et al. (2015) to retrievals from the Greenhouse Gas Observing SATellite (GOSAT). The ratio inversion method uses the measured Xratio as a weak constraint on CO2 fluxes. In contrast, the more common approach of inverting proxy CH4 retrievals (Frankenberg et al., 2005) prescribes atmospheric CO2 fields and optimizes only CH4 fluxes. The TM5-4DVAR inverse modeling system is used to simultaneously optimize the fluxes of CH4 and CO2 for 2009 and 2010. The results are compared to proxy inversions using model-derived-XCO2 mixing ratios (XCO2model) from CarbonTracker and MACC. The performance of the inverse models is evaluated using aircraft measurements from the HIPPO, CONTRAIL and AMAZONICA projects. Xratio and XCO2model are compared with TCCON retrievals to quantify the relative importance of errors in these components of the proxy XCH4 retrieval (XCH4proxy). We find that the retrieval errors in Xratio (mean = 0.61 %) are generally larger than the errors in XCO2model (mean = 0.24 % and 0.01 % for CarbonTracker and MACC, respectively). On the annual time scale, the CH4 fluxes from the different satellite inversions are generally in agreement with each other, suggesting that errors in XCO2model do not limit the overall accuracy of the CH4 flux estimates. On the seasonal time scale, however, larger differences are found due to uncertainties in XCO2model, particularly over Australia and in the tropics. The ratio method stays closer to the a priori CH4 flux in these regions, because it is capable of simultaneously adjusting the CO2 fluxes. Over Tropical South America, comparison to independent measurements shows that CO2 fields derived from the ratio method are less realistic than those used in the proxy method. However, the CH4 fluxes are more realistic, because the impact of unaccounted systematic uncertainties is more evenly distributed between CO2 and CH4. The ratio inversion estimates an enhanced CO2 release from Tropical South America during the dry season of 2010, which is in accordance with the findings of Gatti et al. (2014) and Vanderlaan et al. (2015). The performance of the ratio method is encouraging, because despite the added non-linearity due to the assimilation of Xratio and the significant increase in the degree of freedom by optimizing CO2 fluxes, still consistent results are obtained.
Long-term variability of aerosol optical thickness in Eastern Europe over 2001–2014 according to the measurements at the Moscow MSU MO AERONET site with additional cloud and NO2 correction
Authors: Chubarova N. Y. , Poliukhov A. A. , Gorlova I. D.
Published: February 2016

Abstract. The atmospheric aerosol properties were obtained within the framework of the AERONET program at the Moscow State University Meteorological Observatory (Moscow MSU MO) over the 2001–2014 period. The quality data control has revealed the necessity of additional cloud screening and NO2 correction. The application of additional cloud screening according to hourly visual cloud observations provides a decrease in monthly average aerosol optical thickness (AOT) at 500 nm of up to 0.03 compared with the standard data set. We also show that the additional NO2 correction of the AERONET version 2 data is needed in large megalopolis, like Moscow, with 12 million residents and NOx emission rates of about 100 kt yr−1. According to the developed method, we estimated monthly mean NO2 content, which provides an additional decrease of 0.01 for AOT at 340 nm, and of about 0.015 – for AOT at 380 and 440 nm. The ratios of NO2 optical thickness to AOT at 380 and 440 nm are about 5–6 % in summer and reach 15–20 % in winter when both factors have similar effects on UV irradiance. Seasonal cycle of AOT at 500 nm is characterized by a noticeable summer and spring maxima, and a minimum in winter conditions, changing from 0.08 in December and January up to 0.3 in August. The application of the additional cloud screening removes a local AOT maximum in February. Statistically significant negative trends in annual AOT for UV and mid-visible spectral range have been obtained both for average and 50 % quantile values. The pronounced negative changes were observed in most months with the rate of about −1–5 % yr−1 and could be attributed to the negative trends in emissions (E) of different aerosol precursors of about 135 Gg yr−2 in ESOx, 54 Gg yr−2 in ENMVOC, and slight negative changes in NOx over the European part of Russia. No significant influence of natural factors on temporal AOT variations has been revealed.
Ionospheric correction of GPS radio occultation data in the troposphere
Authors: Zeng Z. , Sokolovskiy S. , Schreiner W. , Hunt D. , Lin J. , Kuo Y.-H.
Published: February 2016

Abstract. For inversions of the GPS radio occultation (RO) data in the neutral atmosphere, this study investigates an optimal transition height for replacing the standard ionospheric correction using the linear combination of the L1 and L2 bending angles with the correction of the L1 bending angle by the L1–L2 bending angle extrapolated from above. The optimal transition height depends on the RO mission (i.e., the receiver and firmware) and is different between rising and setting occultations and between L2P and L2C GPS signals. This height is within the range of approximately 10–20 km. One fixed transition height, which can be used for the processing of currently available GPS RO data, can be set to 20 km. Analysis of the L1CA and the L2C bending angles shows that in some occultations the errors of standard ionospheric correction substantially increase around the strong inversion layers (such as the top of the boundary layer). This error increase is modeled and explained by the horizontal inhomogeneity of the ionosphere.
Global assessment of Vegetation Index and Phenology Lab (VIP) and Global Inventory Modeling and Mapping Studies (GIMMS) version 3 products
Authors: Marshall M. , Okuto E. , Kang Y. , Opiyo E. , Ahmed M.
Published: February 2016

Abstract. Earth observation-based long-term global vegetation index products are used by scientists from a wide range of disciplines concerned with global change. Inter-comparison studies are commonly performed to keep the user community informed on the consistency and accuracy of such records as they evolve. In this study, we compared two new records: (1) Global Inventory Modeling and Mapping Studies (GIMMS) normalized difference vegetation index version 3 (NDVI3g) and (2) Vegetation Index and Phenology Lab (VIP) version 3 NDVI (NDVI3v) and enhanced vegetation index 2 (EVI3v). We evaluated the two records via three experiments that addressed the primary use of such records in global change research: (1) leaf area index (LAI), (2) vegetation climatology, and (3) trend analysis of the magnitude and timing of vegetation productivity. Unlike previous global studies, a unique Landsat 30 m spatial resolution and in situ LAI database for major crop types on five continents was used to evaluate the performance of not only NDVI3g and NDVI3v but also EVI3v. The performance of NDVI3v and EVI3v was worse than NDVI3g using the in situ data, which was attributed to the fusion of GIMMS and MODIS data in the VIP record. EVI3v has the potential to contribute biophysical information beyond NDVI3g and NDVI3v to global change studies, but we caution its use due to the poor performance of EVI3v in this study. Overall, the records were most consistent at northern latitudes during the primary growing season and southern latitudes and the tropics throughout much of the year, while the records were less consistent at northern latitudes during green-up and senescence, and in the great deserts of the world throughout much of the year. These patterns led to general agreement (disagreement) between trends in the magnitude (timing) of NDVI over the study period. Bias in inter-calibration of the VIP record at northernmost latitudes was suspected to contribute most to these discrepancies.
Controls on microalgal community structures in cryoconite holes upon high-Arctic glaciers, Svalbard
Authors: Vonnahme T. R. , Devetter M. , Žárský J. D. , Šabacká M. , Elster J.
Published: February 2016

Abstract. Glaciers are known to harbor surprisingly complex ecosystems. On their surface, distinct cylindrical holes filled with meltwater and sediments are considered hot spots for microbial life. The present paper addresses possible biological interactions within the community of prokaryotic cyanobacteria and eukaryotic microalgae (microalgae) and relations to their potential grazers, such as tardigrades and rotifers, additional to their environmental controls. Svalbard glaciers with substantial allochthonous input of material from local sources reveal high microalgal densities. Small valley glaciers with high sediment coverages and high impact of birds show high biomasses and support a high biological diversity. Invertebrate grazer densities do not show any significant negative correlation with microalgal abundances but rather a positive correlation with eukaryotic microalgae. Shared environmental preferences and a positive effect of grazing are the proposed mechanisms to explain these correlations. Most microalgae found in this study form colonies (< 10 cells, or > 25 µm), which may protect them against invertebrate grazing. This finding rather indicates grazing as a positive control on eukaryotic microalgae by nutrient recycling. Density differences between the eukaryotic microalgae and prokaryotic cyanobacteria and their high distinction in redundancy (RDA) and principal component (PCA) analyses indicate that these two groups are in strong contrast. Eukaryotic microalgae occurred mainly in unstable cryoconite holes with high sediment loads, high N : P ratios, and a high impact of nutrient input by bird guano, as a proxy for nutrients. In these environments autochthonous nitrogen fixation appears to be negligible. Selective wind transport of Oscillatoriales via soil and dust particles is proposed to explain their dominance in cryoconites further away from the glacier margins. We propose that, for the studied glaciers, nutrient levels related to recycling of limiting nutrients are the main factor driving variation in the community structure of microalgae and grazers.
A 368-year maximum temperature reconstruction based on tree ring data in northwest Sichuan Plateau (NWSP), China
Authors: Zhu Liangjun , Zhang Yuandong , Li Zongshan , Guo Binde , Wang Xiaochun
Published: February 2016

Abstract. We present a reconstruction of July–August mean maximum temperature variability for northern West Sichuan Plateau (NWSP), China based on a chronology of tree-ring widths over the period 1646–2013 AD. A regression model explains 37.1 % of the variance of July–August mean maximum temperature during the calibration period from 1954 to 2012. Seven major cold periods were identified including 1708–1711, 1765–1769, 1818–1821, 1824–1828, 1832–1836, 1839–1842 and 1869–1877, and three major warm periods occurred between 1655–1668, 1719–1730 and 1858–1859 in our reconstruction. Comparison with other nearby temperature reconstructions and spatial correlations with gridded land surface temperature dates revealed that our temperature reconstruction has high spatial representativeness. 20th century rapid warming wasn’t obvious in the NWSP mean maximum temperature reconstruction, which implied that mean maximum temperature might play an important and different role in global change as unique temperature indicators. Multi-taper method (MTM) spectral analysis revealed significant periodicities of 170-, 49–114-, 25–32-, 5.7-, 4.6–4.7-, 3.0–3.1-, 2.5- and 2.1–2.3-year quasi-cycles at a 95 % confidence level. The mean maxi mum temperature variability in northwest Sichuan may be affected by ENSO, PDO, AMO and solar activity.
Long-term observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN)
Authors: Birmili W. , Weinhold K. , Merkel M. , Rasch F. , Sonntag A. , Wiedensohler A. , Bastian S. , Schladitz A. , Löschau G. , Cyrys J. , Pitz M. , Gu J. , Kusch T. , Flentje H. , Quass U. , Kaminski H. , Kuhlbusch T. A. J. , Meinhardt F. , Schwerin A. , Bath O. , Ries L. , Wirtz K. , Fiebig M.
Published: February 2016

Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative atmospheric observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both, climate and health related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at seventeen observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan).
Adaptive cycles of floodplain vegetation response to flooding and drying
Authors: Thapa R. , Thoms M. C. , Parsons M. , Reid M.
Published: February 2016

Abstract. Flooding is a key driver of floodplain vegetation productivity. Adaptive cycles provide a model for examining the productivity of semi-arid floodplain vegetation in response to hydrology. We examined the response of vegetation productivity (measured as NDVI) through a hypothesised adaptive cycle to determine whether the cycle repeats over time and how it is affected by differently sized flood events. The area of floodplain inundation was associated with an adaptive cycle that repeated in four flood events through the following phases: wetting (exploitation phase), wet (conservation phase), drying (release phase) and dry (reorganisation phase). Vegetation productivity responses corresponded to these phases. The area and quality of floodplain vegetation productivity followed the hypothesised pattern of higher-quality vegetation vigour in the wetting and wet phases, lower vigour in the drying phase and lowest vigour in the dry phase. There were more transitions between NDVI classes in the wet phase, which was dominated by two-way transitions. Overall, the wetting, wet and drying phases were dominated by smaller-probability class changes, whereas in the dry phase, higher-probability class changes were more prominent. Although the four flood events exhibited an adaptive cycle the duration of the adaptive-cycle phases, and the nature of vegetation productivity response, differed with the character of the flood event. Vegetation response in two of the adaptive-cycle phases – the release and reorganisation phases – were as hypothesised, but in the exploitation and conservation phases, changes in vegetation productivity were more dynamic. The character of vegetation response through the adaptive cycle also indicates that semi-arid floodplain vegetation productivity is more vulnerable to changing state during the conservation and release phases and not during the exploitation and reorganisation phases as resilience theory suggests. Overall, the adaptive cycle represents a new model to improve our understanding of the complexity of change in semi-arid floodplain vegetation productivity through cycles of flooding and drying. Changes in vegetation productivity could initiate structural changes in floodplain vegetation communities, with commensurate influences on floodplain sediment dynamics.
On a neck, on a spit: controls on the shape of free spits
Authors: Ashton A. D. , Nienhuis J. , Ells K.
Published: February 2016

Abstract. We investigate the controls upon the shape of freely extending spits using a one-contour-line model of shoreline evolution. In contrast to existing frameworks that suggest that spits are oriented in the direction of alongshore sediment transport and that wave refraction around the spit end is the primary cause of recurving, our results suggest that spit shoreline shapes are perhaps best understood as graded features arising from a complex interplay between distinct morphodynamic elements: the headland updrift of the spit, the erosive "neck" (which may be overwashing), and the depositional "hook". Between the neck and the hook lies a downdrift-migrating "fulcrum point" which tends towards a steady-state trajectory set by the angle of maximum alongshore sediment transport. Model results demonstrate that wave climate characteristics affect spit growth; however, we find that the rate of headland retreat exerts a dominant control on spit shape, orientation, and progradation rate. Interestingly, as a spit forms off of a headland, the rate of sediment input to the spit itself emerges through feedbacks with the downdrift spit end, and in many cases faster spit progradation may coincide with reduced sediment input to the spit itself. Furthermore, as the depositional hook rests entirely beyond the maximum in alongshore sediment transport, this shoreline reach is susceptible to high-angle wave instability throughout and, as a result, spit depositional signals may be highly autogenic.