bluuebunny/crossref_metadata_2025 huggingface dataset:
Wound bed preparation from a clinical perspective
Authors: Halim A. S. , Khoo T. L. , Mat Saad A. Z.
Published: September 2012

Wound bed preparation has been performed for over two decades, and the concept is well accepted. The ′TIME′ acronym, consisting of tissue debridement, i nfection or inflammation, moisture balance and edge effect, has assisted clinicians systematically in wound assessment and management. While the focus has usually been concentrated around the wound, the evolving concept of wound bed preparation promotes the treatment of the patient as a whole. This article discusses wound bed preparation and its clinical management components along with the principles of advanced wound care management at the present time. Management of tissue necrosis can be tailored according to the wound and local expertise. It ranges from simple to modern techniques like wet to dry dressing, enzymatic, biological and surgical debridement. Restoration of the bacterial balance is also an important element in managing chronic wounds that are critically colonized. Achieving a balance moist wound will hasten healing and correct biochemical imbalance by removing the excessive enzymes and growth factors. This can be achieved will multitude of dressing materials. The negative pressure wound therapy being one of the great breakthroughs. The progress and understanding on scientific basis of the wound bed preparation over the last two decades are discussed further in this article in the clinical perspectives.
Effect of static magnetic field on experimental dermal wound strength
Authors: Ekici Yahya , Aydogan Cem , Balcik Cenk , Haberal Nihan , Kirnap Mahir , Moray Gokhan , Haberal Mehmet
Published: September 2012

Context: An animal model. Aim: We sought to evaluate the effect of static magnetic fields on cutaneous wound healing. Materials and Methods: Male Wistar rats were used. Wounds were created on the backs of all rats. Forty of these animals (M group) had NeFeB magnets placed in contact with the incisions, either parallel (Pa) and perpendicular (Pr) to the incision. The other 40 animals (sham [S] group) had nonmagnetized NeFeB bars placed in the same directions as the implanted animals. Half of the animals in each group were killed and assessed for healing on postoperative day 7 and the other half on postoperative day 14. The following assessments were done: gross healing, mechanical strength, and histopathology. Statistical Analysis Used: Intergroup differences were compared by using the Mann-Whitney U or t test. Values for P less than 0.05 were accepted as significant. Results and Conclusions: There were no differences between the magnetic and sham animals with respect to gross healing parameters. The mechanical strength was different between groups. On postoperative day 14, the MPr14 had significantly higher scores than the other groups. When static, high-power, magnetic fields are placed perpendicular to the wound, increased wound healing occurs in the skin of the experimental model.
Cellular events and biomarkers of wound healing
Authors: Yussof Shah Jumaat Mohd. , Omar Effat , Pai Dinker R. , Sood Suneet
Published: September 2012

Researchers have identified several of the cellular events associated with wound healing. Platelets, neutrophils, macrophages, and fibroblasts primarily contribute to the process. They release cytokines including interleukins (ILs) and TNF-α, and growth factors, of which platelet-derived growth factor (PDGF) is perhaps the most important. The cytokines and growth factors manipulate the inflammatory phase of healing. Cytokines are chemotactic for white cells and fibroblasts, while the growth factors initiate fibroblast and keratinocyte proliferation. Inflammation is followed by the proliferation of fibroblasts, which lay down the extracellular matrix. Simultaneously, various white cells and other connective tissue cells release both the matrix metalloproteinases (MMPs) and the tissue inhibitors of these metalloproteinases (TIMPs). MMPs remove damaged structural proteins such as collagen, while the fibroblasts lay down fresh extracellular matrix proteins. Fluid collected from acute, healing wounds contains growth factors, and stimulates fibroblast proliferation, but fluid collected from chronic, nonhealing wounds does not. Fibroblasts from chronic wounds do not respond to chronic wound fluid, probably because the fibroblasts of these wounds have lost the receptors that respond to cytokines and growth factors. Nonhealing wounds contain high levels of IL1, IL6, and MMPs, and an abnormally high MMP/TIMP ratio. Clinical examination of wounds inconsistently predicts which wounds will heal when procedures like secondary closure are planned. Surgeons therefore hope that these chemicals can be used as biomarkers of wounds which have impaired ability to heal. There is also evidence that the application of growth factors like PDGF will help the healing of chronic, nonhealing wounds.
Pressure ulcers: Back to the basics
Authors: Agrawal Karoon , Chauhan Neha
Published: September 2012

Pressure ulcer in an otherwise sick patient is a matter of concern for the care givers as well as the medical personnel. A lot has been done to understand the disease process. So much so that USA and European countries have established advisory panels in their respective continents. Since the establishment of these organizations, the understanding of the pressure ulcer has improved significantly. The authors feel that the well documented and well publicized definition of pressure ulcer is somewhat lacking in the correct description of the disease process. Hence, a modified definition has been presented. This disease is here to stay. In the process of managing these ulcers the basic pathology needs to be understood well. Pressure ischemia is the main reason behind the occurrence of ulceration. Different extrinsic and intrinsic factors have been described in detail with review of literature. There are a large number of risk factors causing ulceration. The risk assessment scales have eluded the surgical literature and mostly remained in nursing books and websites. These scales have been reproduced for completion of the basics on decubitus ulcer. The classification of the pressure sores has been given in a comparative form to elucidate that most of the classifications are the same except for minor variations. The management of these ulcers is ever evolving but the age old saying of "prevention is better than cure" suits this condition the most.
Venous ulcers of the lower limb: Where do we stand?
Authors: S. Chatterjee Sasanka
Published: September 2012

Venous ulcers are the most common ulcers of the lower limb. It has a high morbidity and results in economic strain both at a personal and at a state level. Chronic venous hypertension either due to primary or secondary venous disease with perforator paucity, destruction or incompetence resulting in reflux is the underlying pathology, but inflammatory reactions mediated through leucocytes, platelet adhesion, formation of pericapillary fibrin cuff, growth factors and macromolecules trapped in tissue result in tissue hypoxia, cell death and ulceration. Duplex scan with colour flow is the most useful investigation for venous disease supplying information about patency, reflux, effects of proximal and distal compression, Valsalva maneuver and effects of muscle contraction. Most venous disease can be managed conservatively by leg elevation and compression bandaging. Drugs of proven benefit in venous disease are pentoxifylline and aspirin, but they work best in conjunction with compression therapy. Once ulceration is chronic or the patient does not respond to or cannot maintain conservative regime, surgical intervention treating the underlying venous hypertension and cover for the ulcer is necessary. The different modalities like sclerotherapy, ligation and stripping of superficial varicose veins, endoscopic subfascial perforator ligation, endovenous laser or radiofrequency ablation have similar long-term results, although short-term recovery is best with radiofrequency and foam sclerotherapy. For deep venous reflux, surgical modalities include repair of incompetent venous valves or transplant or transposition of a competent vein segment with normal valves to replace a post-thrombotic destroyed portion of the deep vein.
Compression therapy for ulcers: The science and the art
Authors: Gogia Shashi B. , Gogia Arun R.
Published: September 2012

Introduction: Chronic ulcers are characterized by being resistant to all forms of treatment. Recent improvement in compression techniques, notably use of multilayer bandaging has created a need for a re-look into it′s use. Materials and Methods: The authors present two case reports of successful management of chronic ulcers using compression through bandaging where all other forms of treatment had failed. This is followed by a review of literature based on previous articles as well as more recent ones found through Pubmed. Conclusion: It is suggested that, at least in India, compression through proper multilayer bandaging, should be a choice far higher in the treatment ladder than so previously. However, if the technique is improper, it may be harmful so the option is to be exercised with care and only by those who have received adequate training. The need of a team approach, and alongside, wider introduction of more and better training facilities for therapists and nurses is underlined.
Wound coverage considerations for defects of the lower third of the leg
Authors: Bajantri Babu , Bharathi R. Ravindra , Sabapathy S. Raja
Published: September 2012

Anatomical features of the lower third of the leg like subcutaneous bone surrounded by tendons with no muscles, vessels in isolated compartments with little intercommunication between them make the coverage of the wounds in the region a challenging problem. Free flaps continue to be the gold standard for the coverage of lower third leg wounds because of their ability to cover large defects with high success rates and feasibility of using it in acute situations by choosing distant recipient vessels. Reverse flow flaps are more useful for the coverage of the ankle and foot defects than lower third leg defects. The perforators in the lower third leg on which these flaps are based are often damaged during the injury. In medium-sized defects of less than 50 cm2 size, local transposition flaps, perforator flaps, or propeller flaps can be used. Preoperative identification by the Doppler is essential before embarking on these flaps. Of the muscle flaps, the peroneus brevis flap can be used in selected cases with small defects. In spite of all recent developments, cross-leg flaps continue to remain as a useful technique. In rare occasions when other flaps are not possible or when other options fail it can be a life boat. In the author′s practice free flaps continue to be the first choice for coverage of wounds in the lower third leg with gracilis muscle flap for small and medium defects, latissimus dorsi muscle flap for large defects and anterolateral thigh flap when a skin flap is preferred.
Improved wound management by regulated negative pressure-assisted wound therapy and regulated, oxygen- enriched negative pressure-assisted wound therapy through basic science research and clinical assessment
Authors: Topaz Moris
Published: September 2012

Regulated negative pressure-assisted wound therapy (RNPT) should be regarded as a state-of-the-art technology in wound treatment and the most important physical, nonpharmaceutical, platform technology developed and applied for wound healing in the last two decades. RNPT systems maintain the treated wound′s environment as a semi-closed, semi-isolated system applying external physical stimulations to the wound, leading to biological and biochemical effects, with the potential to substantially influence wound-host interactions, and when properly applied may enhance wound healing. RNPT is a simple, safe, and affordable tool that can be utilized in a wide range of acute and chronic conditions, with reduced need for complicated surgical procedures, and antibiotic treatment. This technology has been shown to be effective and safe, saving limbs and lives on a global scale. Regulated, oxygen-enriched negative pressure-assisted wound therapy (RO-NPT) is an innovative technology, whereby supplemental oxygen is concurrently administered with RNPT for their synergistic effect on treatment and prophylaxis of anaerobic wound infection and promotion of wound healing. Understanding the basic science, modes of operation and the associated risks of these technologies through their fundamental clinical mechanisms is the main objective of this review.
Exploiting potency of negative pressure in wound dressing using limited access dressing and suction-assisted dressing
Authors: Kumar Pramod
Published: September 2012

Role of negative pressure dressing and moist wound healing are well established in the treatment of both acute and chronic wounds with certain advantages and disadvantages in both the techniques. Both these techniques prevents wound colonization, but the negative pressure dressing method has proved to have a greater potency to remove secretions, prevent wound invasion and eradication established infection. In both these techniques there is no accessibility to wound environment. Limited access dressing (LAD) is a moist wound dressing with negative pressure. It provides limited access to the wound through two small ports for both dressers and pathogens. The LAD design has notable advantages like wound isolation that reduces chance of wound colonization and safe disposal of infected materials (important factor to reduce hospital-acquired infections), while avoiding some major disadvantages such as opacity of dressing materials, inaccessible offensive smelling wound environment, and relatively high treatment costs. In LAD a definite intermittent negative pressure regimen is followed. The intermittent negative pressure (cycle of 30 minutes suction and 3 1 / 2 hours rest) is effective. Overall, the LAD is a safe and effective alternative to conventional dressing methods. LAD is an excellent research tool for wound healing as frequent/continuous record of wound healing is possible without disturbing the wound healing process. LAD is an effective dressing for limb salvage in cases of acute and chronic complex wounds. Leech effect prevents wound related systematic response syndrome and sepsis. Suction-assisted dressing (SAD) is a combination of semiocclusive dressing with negative pressure. It works by removal of fluids by intermittent (like LAD) negative pressure and preventing bacterial invasion. SAD is especially advantageous where soakage is less, there is no dead tissue covering the wound (e.g., following skin grafting), superficial skin wounds (e.g., donor area) and also where LAD is technically difficult to apply over circumferential trunk and neck dressings under anesthesia.
Trophic ulcers-Practical management guidelines
Authors: Puri Vinita , Venkateshwaran N , Khare Nishant
Published: September 2012

The management of patients with trophic ulcers and their consequences is difficult not only because it is a recurrent and recalcitrant problem but also because the pathogenesis of the ulcer maybe different in each case. Methodically and systematically evaluating and ruling out concomitant pathologies helps to address each patient′s specific needs and hence bring down devastating complications like amputation. With incidence of diabetes being high in our country, and leprosy being endemic too the consequences of neuropathy and angiopathy are faced by most wound care specialists. This article presents a review of current English literature available on this subject. The search words were entered in PubMed central and appropriate abstracts reviewed. Relevant full text articles were retrieved and perused. Cross references from these articles were also reviewed. Based on these articles and the authors′ experiences algorithms for management have been presented to facilitate easier understanding. It is hoped that the information presented in this article will help in management of this recalcitrant problem.
The management of perineal wounds
Authors: Parashar Atul , Sharma Ramesh K.
Published: September 2012

Management of perineal wounds can be very frustrating as these invariably get contaminated from the ano-genital tracts. Moreover, the apparent skin defect may be associated with a significant three dimensional dead space in the pelvic region. Such wounds are likely to become chronic and recalcitrant if appropriate wound management is not instituted in a timely manner. These wounds usually result after tumor excision, following trauma or as a result of infective pathologies like hideradenitis suppurativa or following thermal burns. Many options are available for management of perineal wounds and these have been discussed with illustrative case examples. A review of literature has been done for listing commonly instituted options for management of the wounds in perineum.
Recent advances in topical wound care
Authors: Sarabahi Sujata
Published: September 2012

There are a wide variety of dressing techniques and materials available for management of both acute wounds and chronic non-healing wounds. The primary objective in both the cases is to achieve a healed closed wound. However, in a chronic wound the dressing may be required for preparing the wound bed for further operative procedures such as skin grafting. An ideal dressing material should not only accelerate wound healing but also reduce loss of protein, electrolytes and fluid from the wound, and help to minimize pain and infection. The present dictum is to promote the concept of moist wound healing. This is in sharp contrast to the earlier practice of exposure method of wound management wherein the wound was allowed to dry. It can be quite a challenge for any physician to choose an appropriate dressing material when faced with a wound. Since wound care is undergoing a constant change and new products are being introduced into the market frequently, one needs to keep abreast of their effect on wound healing. This article emphasizes on the importance of assessment of the wound bed, the amount of drainage, depth of damage, presence of infection and location of wound. These characteristics will help any clinician decide on which product to use and where,in order to get optimal wound healing. However, there are no ′magical dressings′. Dressings are one important aspect that promotes wound healing apart from treating the underlying cause and other supportive measures like nutrition and systemic antibiotics need to be given equal attention.
Skin substitutes: An Indian perspective
Authors: Singh A. K. , Shenoy Y. R.
Published: September 2012

There have been numerous alternatives developed to replace skin. These can either be permanent substitutes or temporary substitutes, which need to be replaced later by autologous grafts. These have been tried in recent times as an attempt to reduce the need or in the case of permanent substitutes ,altogether replace autologous skin grafts. However till date no ideal skin substitute has been developed. Various factors have to be considered while choosing one of these substitutes. In a developing country like India awareness and availability of these skin substitutes is not adequate considering the volume of cases that require this modality of treatment. Also there are skin substitutes developed in our country that need to be highlighted. This article is an attempt to review the vast array of skin substitutes that have been developed and consider their utility and feasibility for developing countries.
Abnormal pigmentation within cutaneous scars: A complication of wound healing
Authors: Chadwick Sarah , Heath Rebecca , Shah Mamta
Published: September 2012

Abnormally pigmented scars are an undesirable consequence of cutaneous wound healing and are a complication every single individual worldwide is at risk of. They present a challenge for clinicians, as there are currently no definitive treatment options available, and render scars much more noticeable making them highly distressing for patients. Despite extensive research into both wound healing and the pigment cell, there remains a scarcity of knowledge surrounding the repigmentation of cutaneous scars. Pigment production is complex and under the control of many extrinsic and intrinsic factors and patterns of scar repigmentation are unpredictable. This article gives an overview of human skin pigmentation, repigmentation following wounding and current treatment options.
Telemedicine for wound management
Authors: Chittoria Ravi K.
Published: September 2012

The escalating physiological, psychological, social and financial burdens of wounds and wound care on patients, families and society demand the immediate attention of the health care sector. Many forces are affecting the changes in health care provision for patients with chronic wounds, including managed care, the limited number of wound care therapists, an increasingly ageing and disabled population, regulatory and malpractice issues, and compromised care. The physician is also faced with a number of difficult issues when caring for chronic wound patients because their conditions are time consuming and high risk, represent an unprofitable part of care practice and raise issues of liability. Telemedicine enhances communication with the surgical wound care specialist. Digital image for skin lesions is a safe, accurate and cost-effective referral pathway. The two basic modes of telemedicine applications, store and forward (asynchronous transfer) and real-time transmission (synchronous transfer, e.g. video conference), are utilized in the wound care setting. Telemedicine technology in the hands of an experienced physician can streamline management of a problem wound. Although there is always an element of anxiety related to technical change, the evolution of wound care telemedicine technology has demonstrated a predictable maturation process.
A novel and accurate technique of photographic wound measurement
Authors: Shetty Rahul , Sreekar H. , Lamba Shashank , Gupta Ashish Kumar
Published: September 2012

Context: Wound measurement is an important aspect of wound management. Though there are many techniques to measure wounds, most of them are either cumbersome or too expensive. Aims: To introduce a simple and accurate technique by which wounds can be accurately measured. Settings and Design: This is a comparative study of 10 patients whose wounds were measured by three techniques, i.e. ruler, graph and our technique. Materials and Methods: The graph method was taken as the control measurement. The extent of deviation in wound measurements with our method was compared with the standard technique. The statistical analysis used was ANOVA. Results: The ruler method was highly inaccurate and overestimated the wound size by nearly 50%. Our technique remained consistent and accurate with the percentage of over or underestimation being 2-4% in comparison with the graph method. Conclusions: This technique is simple and accurate and is an inexpensive and non-invasive method to accurately measure wounds.
Bladder Neck Rupture following Perineal Bull Horn Injury: A Surgical Challenge
Authors: Padilla Fernandez B. , Diaz Alferez F.J. , Garcia Garcia M.A. , Herrero Polo M. , Velasquez Saldarriaga J.F. , Lorenzo Gomez M.F.
Published: September 2012

Pelvic-abdominal injuries caused by goring are serious lesions which require rapid diagnosis and urgent treatment in the context of a polytraumatized patient. The simultaneous rupture of both the bladder and the prostatic-membranous urethra occurs in 10%-29% of males with pelvic fractures but bladder neck injuries in adults are rarer. Unstable pelvic fractures, bilateral fractures of the ischiopubic branches (also referred to as fractures from falling astride) and the diastasis of the pubic symphysis are those that have the greatest likelihood of injuring both the posterior urethra and the bladder.

We present a case of perineal bull horn injury with muscle laceration, bone fractures, scrotal avulsion and rupture of the bladder neck involving the right ureter which required two operations to be repaired.
Community Participation and Recovery for Mental Health Service Users: An Action Research Inquiry
Authors: Fieldhouse Jon
Published: September 2012

Introduction:

The social inclusion of individuals with mental health problems is an issue for mental health services, for the individuals who experience stigma, discrimination and exclusion, and for society at large. To develop community-orientated services that are capable of promoting inclusion it will, therefore, be advantageous to all parties to understand what service users find most helpful.

Method:

A 2-year action research project explored the recovery journeys of a group of assertive outreach service users who had progressed from being socially excluded and occupationally deprived to being participants in their local communities. The research aimed to understand how these outcomes were produced and to use this knowledge to inform local service development.

Findings:

This paper focuses on eight qualitative interviews, where service users recounted their stories of community participation and inclusion. The findings show how assertive outreach practitioners harnessed occupation as a basis for building relationships between practitioners and service users, and how this became a conduit towards participation in the mainstream community.

Conclusion:

Facilitating engagement in community-based occupations through creative collaboration helped participants reconnect with cherished roles, achieve long-standing goals and develop feelings of self-efficacy, belonging and wellbeing.
Biogenic volatile organic compound emissions during BEARPEX 2009 measured by eddy covariance and flux-gradient similarity methods
Authors: Park J.-H. , Fares S. , Weber R. , Goldstein A. H.
Published: September 2012

Abstract. The Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX) took place in Blodgett Forest, a Ponderosa pine forest in the Sierra Nevada Mountains of California, during summer 2009. We deployed a Proton Transfer Reaction – Mass Spectrometer (PTR-MS) to measure fluxes and concentrations of biogenic volatile organic compounds (BVOCs). Eighteen ion species including the major BVOC expected at the site were measured sequentially at 5 heights to observe their vertical gradient from the forest floor to above the canopy. Fluxes of the 3 dominant BVOCs methanol, 2-Methyl-3-butene-2-ol (MBO), and monoterpenes, were measured above the canopy by the eddy covariance method. Canopy scale fluxes were also determined by the flux-gradient similarity method (K-theory). A universal K (Kuniv) was determined as the mean of individual K's calculated from the measured fluxes divided by vertical gradients for methanol, MBO, and monoterpenes. This Kuniv was then multiplied by the gradients of each observed ion species to compute their fluxes. The flux-gradient similarity method showed very good agreement with the Eddy Covariance method. Fluxes are presented for all measured species and compared to historical measurements from the same site, and used to test emission algorithms used to model fluxes at the regional scale. MBO was the dominant emission observed followed by methanol, monoterpenes, acetone, and acetaldehyde. The flux-gradient similarity method is shown to be a useful, and we recommend its use especially in experimental conditions when fast measurement of BVOC species is not available.
Biological aerosol particle concentrations and size distributions measured in pristine tropical rainforest air during AMAZE-08
Authors: Huffman J. A. , Sinha B. , Garland R. M. , Snee-Pollmann A. , Gunthe S. S. , Artaxo P. , Martin S. T. , Andreae M. O. , Pöschl U.
Published: September 2012

Abstract. As a part of the AMAZE-08 campaign during the wet season in the rainforest of Central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS) was operated for continuous measurements of fluorescent biological aerosol particles (FBAP). In the coarse particle size range (> 1 μm) the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 104 m−3 (4.0–13.2 × 104 m−3) and 0.72 μg m−3 (0.42–1.19 μg mm−3), respectively, accounting for 24% (11–41%) of total particle number and 47% (25–65%) of total particle mass. During the five-week campaign in February–March 2008 the concentration of coarse-mode Saharan dust particles was highly variable. In contrast, FBAP concentrations remained fairly constant over the course of weeks and had a consistent daily pattern, peaking several hours before sunrise, suggesting observed FBAP was dominated by nocturnal spore emission. This conclusion was supported by the consistent FBAP number size distribution peaking at 2.3 μm, also attributed to fungal spores and mixed biological particles by scanning electron microscopy (SEM), light microscopy and biochemical staining. A second primary biological aerosol particle (PBAP) mode between 0.5 and 1.0 μm was also observed by SEM, but exhibited little fluorescence and no fungal staining. This mode consisted of single bacterial cells, brochosomes and various fragments of biological material. Particles liquid-coated with mixed organic-inorganic material constituted a large fraction of observations, and these coatings contained salts likely from primary biological origin. We provide key support for the suggestion that real-time laser-induce fluorescence (LIF) techniques provide size-resolved concentrations of FBAP as a lower limit for the atmospheric abundance of biological particles. We also show that primary biological particles, fungal spores in particular, are key fractions of supermicron aerosol in the Amazon and that, especially when coated by mixed inorganic material, could contribute significantly to hydrological cycling in such regions of the globe.
Characterisation of GOME-2 formaldehyde retrieval sensitivity
Authors: Hewson W. , Bösch H. , Barkley M. P. , De Smedt I.
Published: September 2012

Abstract. Formaldehyde (HCHO) is an important tracer of tropospheric photochemistry, whose slant column abundance can be retrieved from satellite measurements of solar backscattered UV radiation, using differential absorption retrieval techniques. In this work a spectral fitting sensitivity analysis is conducted on HCHO slant columns retrieved from the Global Ozone Monitoring Experiment 2 (GOME-2) instrument. Despite quite different spectral fitting approaches, the retrieved HCHO slant columns have geographic distributions that generally match expected HCHO sources, though the slant column magnitudes and corresponding uncertainties are particularly sensitive to the retrieval set-up. The choice of spectral fitting window, polynomial order, I0 correction, and inclusion of minor absorbers tend to have the largest impact on the fit residuals. However, application of a reference sector correction using observations over the remote Pacific Ocean, is shown to largely homogenise the resulting HCHO vertical columns, thereby largely reducing any systematic erroneous spectral fitting.
Feasibility study of using a "travelling" CO2 and CH4 instrument to validate continuous in-situ measurement stations
Authors: Hammer S. , Konrad G. , Vermeulen A. T. , Laurent O. , Delmotte M. , Jordan A. , Hazan L. , Conil S. , Levin I.
Published: September 2012

Abstract. In the course of the ICOS (Integrated Carbon Observation System)Demo Experiment a feasibility study on the usefulness of a Travelling Comparison Instrument (TCI) was conducted in order to evaluate continuous atmospheric CO2 and CH4 measurements at two European stations. The aim of the TCI is to independently measure ambient air in parallel to the standard station instrumentation, thus providing a comprehensive comparison that includes the sample intake system, the instrument itself as well as its calibration and data evaluation. Observed differences between the TCI and the Heidelberg gas chromatographic system, which acted as a reference for the TCI, were −0.02 ± 0.08 μmol mol−1 for CO2 and −0.3 ± 2.3 nmol mol−1 for CH4. Over a period of two weeks each, the continuous CO2 and CH4 measurements at two ICOS field stations, Cabauw and OPE, were compared to co-located TCI measurements. At Cabauw mean differences of 0.21 ± 0.06 μmol mol−1 for CO2 and 0.41 ± 0.50 nmol mol−1 for CH4 were found. For OPE the mean differences were 0.13 ± 0.07 μmol mol−1 for CO2 and 0.44 ± 0.36 nmol mol−1 for CH4. Potential causes of these observed differences are leakages or contaminations in the intake lines and/or there flushing pumps. At Cabauw station an additional error contribution originates from insufficient flushing of standard gases. Offsets arising from differences in the working standard calibrations or leakages/contaminations in the drying systems are too small to explain the observed differences. Finally a comprehensive quality management strategy for atmospheric monitoring networks is proposed.
Technical Note: The effects of five different defaunation methods on biogeochemical properties of intertidal sediment
Authors: Tolhurst T. J. , Chapman M. G. , Underwood A. J. , Cruz J. J.
Published: September 2012

Abstract. Various methods have been used to remove organisms from sediments to investigate structure and function of faunal assemblages in intertidal habitats. Nevertheless, little is known about how these treatments affect properties of the sediments themselves, although changing these properties may cause changes in the assemblages, independently of other hypotheses being tested. This study assesses the efficacy of defaunation and effect on selected biogeochemical properties of five different methods of defaunating soft muddy sediments in an estuary. The methods were removal and freezing of sediment, removal and oven-heating, freezing in situ with liquid N2, spraying with formalin and spraying with hydrogen peroxide. The first four of these methods have been used in previous studies, whilst the fifth was considered to be a potentially useful defaunator because it does not leave toxic residues. The first two methods required sediment to be brought back to the lab, disrupting the natural structure of the sediment; the last three were done in situ, with much less disturbance. Variables measured to assess effects of the treatments on the sediment were amount of water, grain size, total carbohydrate, suspension index (relative erosion rate), erosion threshold, chlorophyll a and b, colloidal carbohydrate, Fo (minimal fluorescence) and Fv / Fm (photosynthetic yield). There were no significant effects of any treatment on the first four variables. For the others, effects of defaunation varied from treatment to treatment and with time after treatment. Generally, the greatest disturbance was to the microphytobenthos (MPB, measured by chlorophyll and fluorescence) and related variables. For most treatments, recovery was rapid, but the effects of formalin and H2O2 persisted for a few days. Effects on physical properties of the sediment were mostly minor and insignificant. Removal and freezing or heating, however, caused major changes to the sediments because of the disturbances involved. Choosing the appropriate method of defaunation is very important if interpretations are not to be confounded between the effects of defaunation per se and any effects of changes to other biota (such as microphytobenthos) and/or the properties of sediments caused by the method used to defaunate experimental areas.
Can we predict the duration of an interglacial?
Authors: Tzedakis P. C. , Wolff E. W. , Skinner L. C. , Brovkin V. , Hodell D. A. , McManus J. F. , Raynaud D.
Published: September 2012

Abstract. Differences in the duration of interglacials have long been apparent in palaeoclimate records of the Late and Middle Pleistocene. However, a systematic evaluation of such differences has been hampered by the lack of a metric that can be applied consistently through time and by difficulties in separating the local from the global component in various proxies. This, in turn, means that a theoretical framework with predictive power for interglacial duration has remained elusive. Here we propose that the interval between the terminal oscillation of the bipolar seesaw and three thousand years (kyr) before its first major reactivation provides an estimate that approximates the length of the sea-level highstand, a measure of interglacial duration. We apply this concept to interglacials of the last 800 kyr by using a recently-constructed record of interhemispheric variability. The onset of interglacials occurs within 2 kyr of the boreal summer insolation maximum/precession minimum and is consistent with the canonical view of Milankovitch forcing pacing the broad timing of interglacials. Glacial inception always takes place when obliquity is decreasing and never after the obliquity minimum. The phasing of precession and obliquity appears to influence the persistence of interglacial conditions over one or two insolation peaks, leading to shorter (~ 13 kyr) and longer (~ 28 kyr) interglacials. Glacial inception occurs approximately 10 kyr after peak interglacial conditions in temperature and CO2, representing a characteristic timescale of interglacial decline. Second-order differences in duration may be a function of stochasticity in the climate system, or small variations in background climate state and the magnitude of feedbacks and mechanisms contributing to glacial inception, and as such, difficult to predict. On the other hand, the broad duration of an interglacial may be determined by the phasing of astronomical parameters and the history of insolation, rather than the instantaneous forcing strength at inception.
Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy
Authors: Vannière B. , Magny M. , Joannin S. , Simonneau A. , Wirth S. B. , Hamann Y. , Chapron E. , Gilli A. , Desmet M. , Anselmetti F. S.
Published: September 2012

Abstract. Two lacustrine sediment cores from Lake Ledro in Northern Italy were studied to produce chronologies of flood events for the past 10 000 yr. For this purpose, we have developed an automatic method that objectively identifies the sedimentary imprint of river floods in the downstream lake basin. The automatic counting of flood deposits was based on colour data extracted from processed core photographs, and the count data were processed to capture the flood signal. Automatic quantification was compared with naked-eye counting. Counts were performed twice on the proximal and distal cores to provide an objective and reproducible record of flood frequency. Geophysical and geochemical analyses made it possible to distinguish event deposits from background sedimentation. Flood frequency and reconstructed sedimentary dynamics were compared with lake-level changes and pollen dynamics inferred from vegetation data. The data suggest a record marked by low flood frequency during the early and middle Holocene (10 000–4500 cal BP). Only modest increases during short intervals are recorded at ca. 8000, 7500, and 7100 cal BP. The last third of the Holocene is characterised by a shift toward increased flood frequency at ca. 4500–4000 cal BP. With the exception of two short intervals around 2900–2500 and 1800–1400 cal BP, which show a slightly reduced number of floods, the trend of increasing flood frequency prevailed until the 20th century, reaching a maximum between the 16th and the 19th centuries. Brief-flood frequency increases recorded during the early and middle Holocene can be attributed to cold climatic oscillations. On a centennial time scale, major changes in flood frequency, such as those observed at ca. 4500 and 500 cal BP, can be attributed to large-scale climatic changes such as the Neo-glacial and Little Ice Age, which are under orbital and possibly solar control. The role of climate as the main forcing factor in flood activity is supported by the lake-level records: the major lake-level rises are synchronous with flood frequency increases. However, in the Bronze Age and during the Middle Ages and modern times, forest clearing and land use are indicated by pollen and archaeological data. These human activities have clearly affected the sediment record of flood activity, and they can partially explain the amplitude of the increases in flood activity.
On the relation between Meridional Overturning Circulation and sea-level gradients in the Atlantic
Authors: Kienert H. , Rahmstorf S.
Published: September 2012

Abstract. On the basis of model simulations, we examine what information on changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) can be extracted from associated changes in sea surface height (SSH), specifically from a broad Atlantic north–south gradient as has been suggested previously in the literature. Since a relation between AMOC and SSH changes can only be used as an AMOC diagnostic if it is valid independently of the specific forcing, we consider three different forcing types: increase of CO2 concentration, freshwater fluxes to the northern convection sites and the modification of Southern Ocean winds. We concentrate on a timescale of 100 yr. We find approximately linear and numerically similar relations between a sea-level difference within the Atlantic and the AMOC for freshwater as well as wind forcing. However, the relation is more complex in response to atmospheric CO2 increase, which precludes this sea-level difference as an AMOC diagnostic under climate change. Finally, we show qualitatively to what extent changes in SSH and AMOC strength, which are caused by simultaneous application of different forcings, correspond to the sum of the changes due to the individual forcings, a potential prerequisite for more complex SSH-based AMOC diagnostics.
CCC-based muon telescope for examination of natural caves
Authors: Oláh L. , Barnaföldi G. G. , Hamar G. , Melegh H. G. , Surányi G. , Varga D.
Published: September 2012

Abstract. A portable cosmic muon detector has been developed for geophysical application: searching for large scale underground rock/soil inhomogeneities and underground cavities. The designed muon telescope called Muontomograph is based on the recently developed Closed Cathode Chamber (CCC) technology, which provides a cheap, easy handling, portable, and power efficient detector system, able to work even at extreme conditions (e.g. high humidity, low/high temperature). The muon telescope has about 0.1 m2 detection surface with 10 mrad angular resolution. Tests have been performed in natural caves and artificial tunnel systems as well. In the paper a summary of the first results on tomographed cavities are presented and the geophysical and possible industrial use of the cosmic muon tomograph technology is indicated.
Generating spatial precipitation ensembles: impact of temporal correlation structure
Authors: Rakovec O. , Hazenberg P. , Torfs P. J. J. F. , Weerts A. H. , Uijlenhoet R.
Published: September 2012

Abstract. Sound spatially distributed rainfall fields including a proper spatial and temporal error structure are of key interest for hydrologists to force hydrological models and to identify uncertainties in the simulated and forecasted catchment response. The current paper presents a temporally coherent error identification method based on time-dependent multivariate spatial conditional simulations, which are conditioned on preceding simulations. A sensitivity analysis and real-world experiment are carried out within the hilly region of the Belgian Ardennes. Precipitation fields are simulated for pixels of 10 km × 10 km resolution. Uncertainty analyses in the simulated fields focus on (1) the number of previous simulation hours on which the new simulation is conditioned, (2) the advection speed of the rainfall event, (3) the size of the catchment considered, and (4) the rain gauge density within the catchment. The results for a sensitivity analysis show for typical advection speeds >20 km h−1, no uncertainty is added in terms of across ensemble spread when conditioned on more than one or two previous hourly simulations. However, for the real-world experiment, additional uncertainty can still be added when conditioning on a larger number of previous simulations. This is because for actual precipitation fields, the dynamics exhibit a larger spatial and temporal variability. Moreover, by thinning the observation network with 50%, the added uncertainty increases only slightly and the cross-validation shows that the simulations at the unobserved locations are unbiased. Finally, the first-order autocorrelation coefficients show clear temporal coherence in the time series of the areal precipitation using the time-dependent multivariate conditional simulations, which was not the case using the time-independent univariate conditional simulations. The presented work can be easily implemented within a hydrological calibration and data assimilation framework and can be used as an improvement over currently used simplistic approaches to perturb the interpolated point or spatially distributed precipitation estimates.
On the utility of land surface models for agricultural drought monitoring
Authors: Crow W. T. , Kumar S. V. , Bolten J. D.
Published: September 2012

Abstract. The lagged rank cross-correlation between model-derived root-zone soil moisture estimates and remotely sensed vegetation indices (VI) is examined between January 2000 and December 2010 to quantify the skill of various soil moisture models for agricultural drought monitoring. Examined modeling strategies range from a simple antecedent precipitation index to the application of modern land surface models (LSMs) based on complex water and energy balance formulations. A quasi-global evaluation of lagged VI/soil moisture cross-correlation suggests, when globally averaged across the entire annual cycle, soil moisture estimates obtained from complex LSMs provide little added skill (< 5% in relative terms) in anticipating variations in vegetation condition relative to a simplified water accounting procedure based solely on observed precipitation. However, larger amounts of added skill (5–15% in relative terms) can be identified when focusing exclusively on the extra-tropical growing season and/or utilizing soil moisture values acquired by averaging across a multi-model ensemble.
Surface deformation detected by the space-observed small baseline SAR interferometry over permafrost environment in Tibet Plateau, China
Authors: Chen F. , Lin H.
Published: September 2012

Abstract. The evolution of permafrost and the active layer is highly related to climate change because of its feedback effects involving water and carbon storage. In this study, we firstly examined the relationship of regional water balance, geomorphological process and anthropogenic activities by means of Small Baseline Synthetic Aperture Radar Interferometry (SB-InSAR) to monitor the surface movements overlaid on the permafrost of Tibet Plateau (TP), China, using 3.5-yr observation span of L-band ALOS PALSAR data (June, 2007 to December, 2010). The estimated displacements (primarily in the range of −30 mm yr−1 to 30 mm yr−1) and time-series implied evolutions of the active layer and permafrost beneath. The motion trend along slopes was complicated, and thus interdisciplinary interpretations were required. Water level variations of inland lakes were then detected, although further investigations were required for validation. Anthropogenic influences on this frail permafrost environment were significant, proved by the remarkable surface settlement along the embankment of Qinghai-Tibet Railway. Consequently, it is crucial and necessary to monitor this arid and cold plateau owing to the combination of climate change, geo-hazards prediction as well as the regional sustainable development.