bluuebunny/crossref_metadata_2025 huggingface dataset:
An assessment of the accuracy of tattoo marks in aligning treatment fields for pelvic radiotherapy
Authors: Mowbray J. , Bonnett D. E.
Published: August 2006

Electronic portal imaging (EPI) has been used in the assessment of the accuracy of radiotherapy treatments in the pelvis. The daily reproducibility of any treatment is primarily dependent on the effectiveness of the set-up method. Treatments of radical planned volumes within the pelvis are subject to field placement errors (FPE) which could potentially compromise the successful outcome of radiotherapy treatment. Increasing use of shaped treatment fields to limit the dose delivered to surrounding normal tissues has prompted a more detailed examination of set-up methods.

Within the radiotherapy department at the Leicester Royal Infirmary it was noted that tattooed marks on the anterior or posterior and the lateral skin surface, marked at simulation, could not always be aligned for daily radiotherapy treatment.

An assessment of the relative merit of the anterior/posterior or the lateral tattoos in determining the isocentre position in the superior-inferior (cranio-caudal) plane is presented. This study showed that changes in the use of tattoo marks during set-up would have reduced the incidence of FPE >5 mm for a small sample group of patients. Implementation of changes in clinical practice, or research using a larger sample group is now needed to verify any improvement in accuracy using a modified treatment set-up technique.
The effect of the recommendation of two different physical activity strategies on fatigue experienced during radiotherapy
Authors: Flinton D. M. , Thorne R. J. , Waller S. , Nelson N. , Thapar-Francis P. , Cherry P.
Published: August 2006

Patients undergoing cancer treatments, including radiotherapy, frequently report fatigue during their treatment. Recent research indicates that structured exercise programmes can alleviate fatigue and, in light of this research, many centres are now advocating activity as part of the strategy with which to combat fatigue. The aim of this investigation was to see how well this strategy would be received by patients and what effect it would have on fatigue levels. Of the 147 patients who agreed to take part in the study 123 completed all the questionnaires. Fiftyfour of the patients received the standard advice whilst 69 received the modified advice. Fatigue was measured at four time points using the MFI scale. Fatigue scores at the end of treatment were significantly higher than at the start of treatment but there was no difference in fatigue scores between the two groups of patients receiving the different advice. Activity levels between the two groups were comparable, as was their change in activity level compared to normal, indicating a reluctance to use this strategy.
An overview of age-related macular degeneration and its management using external beam radiotherapy
Authors: Newnham John
Published: August 2006

This paper aims to provide an overview of age related macular degeneration (ARMD) and its radiotherapy management.

ARMD is already the leading cause of adult blindness in the western world. The neovascular form of ARMD is responsible for some 85% of blindness caused by ARMD as a whole. Its aetiology is unknown. The natural course of the disease is rapid progression from onset to disciform scarring and accompanying loss of visual acuity. Laser photocoagulation is only suitable for 10% of patients with neovascular ARMD. Initial studies using low dose fractionated external beam radiotherapy have demonstrated stable visual acuity over the range of 40–93% at short term follow-up. Only transient acute side effects have been observed. No radiation-induced retinopathy or vasculopathy have been observed. Common radiotherapy macula techniques are reviewed, field sizes examined and criteria for a simple macula technique proposed. A subset of patients with rapidly progressing neovascular ARMD may be candidates for rapid treatment starts. Although follow up times have been short, radiotherapy is a promising option for those patients facing imminent blindness due to rapidly progressive neovascular ARMD.
Interprofessional work in cancer care: towards team work through interprofessional education
Authors: Hammick M. , Robertshaw H.
Published: August 2006

This paper explores some of the characteristics associated with learning about the care and management of people with cancer in an interprofessional setting. Most cancer patients have contact with a variety of health care professionals on their cancer journey. This journey is explored for a woman with breast cancer who experiences, reports and receives advice for the chronic fatigue that many such patients have during and after treatments. Recent literature, especially that informed by patients’ viewpoints, indicates that some patients perceive their care as fragmented and can be given conflicting advice from different professionals within the team. This paper demonstrates that working in an interprofessional way is full of complexities for the practitioners involved and argues for interprofessional education as a way towards more effective team work when two or more health care professionals are members of that team.

The paper discusses theoretical aspects of interprofessional education, with a focus on knowledge development through shared learning and how this may be achieved for students studying cancer care. Barriers to the effective development of interprofessional knowledge are elaborated upon.
The effect of implementing ICRU 50 in breast radiotherapy technique: the significance of inhomogeneities and off axis ratios
Authors: Cornelius N.
Published: August 2006

This report examines the recommendations of The International Commission for Radiation Units and Measurements, ICRU 50 and a typical interpretation of them. It hypothesises that there is a small identifiable group of patients that may be at risk of long term damage due to current radiotherapy treatment to the breast.

The report emphasises the variation in dose obtained when the whole volume of the irradiated breast is considered. The dose distribution beyond the central contour and the effect of lung density is analysed. Even if three-dimensional planning and inhomogeneity correction factors are not available, consideration must be given to their significance.

This report acknowledges that the ICRU reference point is a much-needed method of comparing radiotherapy treatments between hospitals, but points out that it was not intended to be a means of determining dosimetry, despite the suggestion that it may be advantageous if its relative dose is 100%.

The report concludes that there should be greater awareness and attention paid to the recommendation that heterogeneity should be within +7 and −5% of the prescribed dose.
Issues surrounding the use of helical CT for the imaging and planning of lung tumours
Authors: Eddy A.
Published: August 2006

In this article several issues will be discussed. Firstly, the efficacy of using helical CT data to image the thorax, and delineate volumes (clinical target volumes (CTV) and planning target volumes (PTV). Secondly, the practicalities of using CT data sets for dose inhomogeneity corrections and planning in the thorax. And thirdly, the associated problems of organ motion and immobilisation in this region.
Radiotherapy dose and fractionation regimens prescribed for Non-Hodgkin's Lymphoma (a local study)
Authors: Young W. , Meredith C.
Published: August 2006

Background: Non-Hodgkin's Lymphomas (NHL) are considered to be a highly radiosensitive group of diseases with radiotherapy playing a major role in their treatment. It is recognised that the different grades and stages of NHL require different treatment approaches with current recommendations including combined chemotherapy and radiotherapy, chemotherapy alone or radiotherapy alone. Despite these recommendations there still remains a variation in the radiotherapy dose and fractionation regimens prescribed for NHL and this could be attributed to a lack of written treatment protocols for these patients. This paper gives an overview of the literature and reports on a small local study.

Method: A retrospective study recorded the treatment details of 35 patients treated with radiotherapy for NHL between April and September 1996 in a major radiotherapy centre. An analysis of the various radiotherapy dose and fractionation regimens identified was carried out and an attempt to identify the rationale behind the variations was made by correlating them to the grade of disease, the age of the patients, the prescribing consultants and whether chemotherapy was part of the treatment regimen.

Results: Thirteen consultants were identified as prescribing treatment for NHL. Forty-nine percent of patients presented as low, 11% intermediate and 31% high grade NHL. Of the 60% of patients who underwent chemotherapy the majority (62%) were prescribed Cyclophosphamide, Hydroxydaunorubicin, Oncovin (Vincristine) and Prednisolone (the CHOP regimen). Nineteen different radiotherapy dose and fractionation regimens were identified, 20 Gy in 5 fractions being the most common. No correlation was found between the age of the patients and the radiotherapy dose delivered. A strong positive relationship (r = 0.95) was identified between the radiotherapy dose and the number of fractions. There was no effect on the radiotherapy dose delivered between the different grades of disease or whether chemotherapy was administered.

Conclusions: It is considered that the implementation of a NHL treatment protocol is important and in an attempt to initiate this, specific NHL teams should be formed.
Strategies to reduce clinical file server downtime
Authors: Jackson David J. B.
Published: August 2006

Radiotherapy departments are increasingly reliant on networked computers to co-ordinate all aspects of radiotherapy treatment such as treatment planning, verification or simulation. This paper suggests three relatively inexpensive strategies that can be applied to file servers within such networks. If they are implemented, the additional resilience of the network will increase the number of clinically available hours as most common hardware problems can be scheduled for repair outside routine clinical use.
Complementary medicine in cancer care: legal issues of medical negligence and redress
Authors: White Peter
Published: August 2006

Aims: To compare and contrast how the law relating to medical negligence in England and Wales applies to conventional and complementary practice and to outline some of the legal issues which may arise. Methods: A thorough review of the literature was used to collect relevant information. This involved a comparative analysis of documentation, including Statutory Powers, Statutory Instruments, case law, books and journal publications. Results and discussion: Complementary therapists, regardless of whether they are private or NHS employees, are bound by the same duty of care for their patients as conventional practitioners and the same legal rules apply. If complementary therapists claim to possess special skills, then they are liable for actions arising out of clinical practice, in the same way as conventional practitioners. State registration, for the mainstream complementary therapies, is one way of improving the status of such professions as they become an integral part of the management of cancer patients. However, until they are fully integrated, a balance must be achieved so as to overcome any conflicts of interest between complementary and conventional healthcare practitioners and to facilitate acceptance of the former into the healthcare team. Conclusions: As complementary therapies are integrated into the care of cancer patients, controls and regulations must be implemented, possibly influenced by a legal framework, so as to establish a foundation for enhancing or adding authority to the ethical issues and guidelines which already exist.
Part 3: Autonomy, paternalism, advocacy and consent
Authors: Smith G. E.
Published: August 2006

In the past 50 years, informed consent has become a fundamental principle of health care ethics. With the introduction of new technology and new techniques in radiotherapy practice, practitioners must be aware of the ethical dimensions of their work and be able to organize their understanding of the issues. Informed consent is based on the recognition of the patient as an autonomous agent. This paper commences by defining autonomy and its supposed opposite concept – paternalism, as well as discussing patient advocacy and illustrating these concepts in the context of informed consent in radiotherapy practice. Practitioners must mould themselves not only to be knowledgeable and skilled professionals but also to be respectful and caring human beings.
A randomised controlled trial to test a non-metallic deodorant used during a course of radiotherapy
Authors: Gee A. , Moffitt D. , Churn M. , Errington R.D.
Published: August 2006

Background: Radiotherapy skin reactions have been well documented in the past. Until recently, washing of the treated area and the use of perfumed products that contain metals has not been advocated during treatment. The aims of this study were to assess the skin reactions of patients using a non-metallic deodorant and to see whether there were any psychological benefits from being able to use the deodorant.

Method: 41 women attending for radiotherapy to either the breast or breast and axilla were recruited into the trial. They were randomised into one of two groups. Complete data was obtained for 36 patients. 20 patients used the deodorant and 16 did not. Any skin reactions noted were recorded on a weekly basis. Patients were also asked to complete a questionnaire relating to feelings and activities and to comment on the deodorant if they had used it.

Results: Skin reactions did seem to be slightly worse in the patients using deodorant, and it was only in this group of patients that axillary reactions were noted. However, neither of these results were statistically significant. The use of the deodorant did not have any impact on the psychological well being of the patients, but patients using it had found it pleasant to use and the majority said that they would use it again.

Conclusion: Further study is indicated to look at skin reactions using the deodorant with a larger sample of patients.
Hormonanalysen im Urin
Authors: Mohaupt  , von Vigier
Published: August 2006

Hormonanalysen im Urin werden vorwiegend angewendet, um Störungen des Steroidhormonmetabolismus, um eine erhöhte Produktion biogener Amine und um nicht invasiv humanes β-Choriogonadotropin als Proteinhormon als Indikator einer Schwangerschaft nachweisen zu können. Diese Untersuchungen müssen gegebenenfalls von Plasma-/ Serumbestimmungen komplementiert werden. Klinische Daten einschließlich der aktuellen Medikation sowie das Urinkreatinin als Bezugsgröße sind unabdingbar zur seriösen Beurteilung einer Urinuntersuchung. Die wichtigsten Krankheitsbilder, die mittels Steroidhormonanalyse untersucht werden können, sind der Exzess eines typischen oder atypischen mineralokortikoid wirksamen Steroidhormons, die Hormonaktivität eines Nebennieren- oder ovariellen Tumors, Akne unklarer Ätiologie, Hirsutismus, ein PCO-, ein adrenogenitales oder ein vermutetes Cushingsyndrom. Die Untersuchung biogener Amine wird durchgeführt bei Verdacht auf eine sekundäre bzw. therapierefraktäre Hypertonie, bei Auftreten phäochromozytom- oder paragangliom-assoziierter Symptome oder Verdacht auf einen serotininproduzierenden Tumor. Bei Kindern steht die Suche nach genetisch determinierten Erkrankungen im Vordergrund.
Urindiagnostik bei Nephrolithiasis – Interpretation und therapeutische Konsequenzen
Authors: Pasch
Published: August 2006

Die Nephrolithiasis ist eine Erkrankung mit hoher und aktuell sogar noch steigender Inzidenz. Sie ist mit großer Morbidität und hohen Kosten für das Gesundheitswesen verbunden und besitzt eine hohe Rezidivrate. Urinuntersuchungen sind bei der Evaluation rezidivierender Steinbildner von entscheidender Bedeutung und ermöglichen die Identifikation und Quantifizierung von Risikofaktoren sowie die Erstellung eines individuellen Risikoprofils. Durch ein hierauf beruhendes rationales Therapiekonzept zur Metaphylaxe von Nierensteinen kann das Risiko weiterer Rezidivsteine deutlich gesenkt werden. Dieser Reviewartikel gibt einen fokussierten Überblick über die wichtigsten praktisch relevanten Risikofaktoren und die sinnvollen Urinuntersuchungen zur Abklärung einer rezidivierenden Nephrolithiasis.
Urindiagnostik beim Kind
Authors: Simonetti  , Konrad
Published: August 2006

Die Urindiagnostik bei Kindern ist komplex und die Schwierigkeiten beginnen insbesondere bei Säuglingen und Kleinkindern bereits bei der Uringewinnung. Mittelstrahlurin ist eine gute Methode für Kinder mit Blasenkontrolle, bei Säuglingen ist zum Nachweis von Harnwegsinfektionen meist eine Blasenkatheterisierung oder eine suprapubische Blasenpunktion notwendig. Die Uringewinnung mittels Urinsäckli darf nur zum Ausschluss und nicht für die Diagnose von Harnwegsinfektionen angewendet werden. Eine Urinkultur sollte auf keinen Fall von einem Urinsäckli abgenommen werden. Die oft gewünschte 24-Stunden-Urinsammlung muss im Säuglingsalter durch die Einzelprobe ersetzt werden, wobei die gemessenen Konzentrationen im Verhältnis zur Kreatinin-Konzentration angegeben werden.
Kristallurie
Authors: Henschkowski  , Vogt
Published: August 2006

Kristalle werden häufig bei der Routine-Untersuchung des Urins gefunden und als Kristallurie bezeichnet. Meistens entsteht die Kristallurie durch eine vorübergehende Übersättigung des Urins. Aber auch Nahrungsmittel, oder Änderungen von pH und Temperatur des Urins, z.B. wenn der Urin nach der Miktion länger stehen geblieben ist, können zu Kristallurie führen. Diese zufällig beobachtete Kristallurie hat keinen Krankheitswert. Der Nachweis von Kristallen im Urin kann jedoch auch mit krankhaften Zuständen, wie Urolithiasis, primärer Hyperoxalurie und Ethylenglycol-Vergiftung einhergehen. Zusätzlich führen verschiedene Medikamente, vor allem antivirale Substanzen und Antibiotika unter bestimmten Umständen zu Kristallurie mit zum Teil schwerwiegenden Nierenschädigungen. In diesen Fällen ist die Untersuchung der Kristalle im Urin zum einen diagnostisch hilfreich zum anderen ist sie ein wichtiger Verlaufsparameter. Voraussetzung für die Beurteilung der Kristallurie ist die korrekte Probenaufbereitung, Bestimmung und Einordnung des Urin-pH und Kenntnis des mikroskopischen Verfahrens.
Der rote Urin – wie weiter?
Authors: Wüthrich  , Serra
Published: August 2006

Der rote Urin kann auf eine schwerwiegende Erkrankung hinweisen und erfordert deshalb eine sorgfältige Beurteilung. In vielen Fällen kann mittels klinischer Befragung und Untersuchung, einfachem Urinstreifentest- und Urinsedimentanalyse, Serumkreatinin und geschätzter Nierenfunktion sowie der orientierenden Ultraschalluntersuchung bereits in der Praxis eine Grobdiagnose gestellt werden. Die isolierte Mikrohämaturie beim über 50-jährigen Patienten sowie die Mikrohämaturie mit begleitender Proteinurie und/oder eingeschränkter Nierenfunktion erfordern weitergehende Abklärungen. Bei einigen Patienten (vor allem jüngeren) kann selbst mit ausgedehnter Diagnostik keine klare Ursache einer isolierten Mikrohämaturie identifiziert werden. Es empfiehlt sich in diesen Fällen, eine jährliche Nachkontrolle vorzusehen zur Überwachung des Urinsediments, und um eine beginnende Proteinurie oder eine neue Hypertonie rechtzeitig festzustellen.
Pathophysiologie und Diagnostik renal tubulärer Azidosen
Authors: Ambühl
Published: August 2006

Isolierte Störungen der renalen Tubulusfunktion, welche bei normaler glomerulärer Filtrationsrate zu verminderter Säureausscheidung oder renalem Basenverlust und metabolischer Azidose führen, bezeichnet man als renal tubuläre Azidosen (RTA). Aufgrund der Lokalisation entlang des Tubulus (proximal/distal) und aufgrund assoziierter Störungen (Hypo-/Hyperkaliämie) unterscheidet man verschiedene Formen der RTA (proximale RTA, RTA Typ II; hypokaliämische distale RTA, RTA Typ I; generalisierte hyperkaliämische distale RTA, RTA Typ IV). Die meisten Formen resultieren in einer positiven Säurebilanz des Organismus und haben damit Auswirkungen auf den Knochenstoffwechsel oder die Bildung von Nierensteinen. Die Diagnostik beruht auf der Analyse des systemischen Säure-/Basenstatus, der Untersuchung verschiedener Urinparameter (pH, Citraturie) und in einzelnen Fällen auf Spezialuntersuchungen (beispielsweise Säurebelastungstest). Als Ursache der RTA kommen selektive Funktionsstörungen verschiedener tubulärer Transportproteine und Ionenkanäle in Betracht, oder aber unspezifische generalisierte tubulointerstitielle Erkrankungen. Die Behandlung der RTA beruht einerseits in der Therapie allfälliger Erkrankungen, andererseits auf der Korrektur der Azidose mittels Basensubstitution.
Chronische Hepatitis – Aktuelle Diagnostik
Authors: Blum
Published: August 2006

Die Diagnostik bei Patienten mit chronischer Hepatopathie umfasst Anamnese, klinische Untersuchung, einschliesslich Ultraschall/Duplexsonographie, allgemeine klinisch-chemische Untersuchungen (Basisdiagnostik), ätiologie-definierende Laboranalysen, spezielle bildgebende Untersuchungen und ggf. eine perkutane oder transjuguläre Leberbiopsie bzw. eine Laparoskopie. Damit lässt sich in den meisten Fällen die Ursache der Lebererkrankung identifizieren. Dies ist Voraussetzung für die Beurteilung der Prognose und des Verlaufs der Hepatopathie sowie für die Therapieindikation und -evaluation sowie die Wahl der optimalen therapeutischen Strategie. Von besonderer Bedeutung ist bei der Erstdiagnose jeder Hepatopathie der sichere Ausschluss bzw. die Identifikation von koexistierenden Ursachen, z.B. Alkoholgenuss und chronische Hepatitis C.
Abklärung wegen Gewichtsverlust, Anorexie, Nausea und epigastrischen Schmerzen
Authors: Schafroth Török  , Tornillo  , Keller
Published: August 2006

Kardiale Myxome sind selten. Sie sind zwar histologisch gutartig, können aber mit lebensbedrohlichen Komplikationen einhergehen. Die klassische Symptomtrias besteht aus Symptomen der intrakardialen Obstruktion, Symptomen einer Embolisation von Tumorfragmenten oder Thromben sowie Allgemeinsymptomen. Eine sofortige operative Entfernung des Tumors ist immer anzustreben.
Computing magnetospheric mass density from field line resonances in a realistic magnetic field geometry
Authors: Berube D. , Moldwin M. B. , Ahn M.
Published: August 2006

Ultra‐low‐frequency (ULF) field line resonances can be used to infer the mass density along magnetospheric magnetic field lines. By specifying how mass density is distributed along the magnetic field (usually a power law as a function of distance from the Earth) and a dipole magnetic field geometry, the MHD standing wave equation can be analytically solved and mass density inferred from observed field line eigenfrequencies. However, the geometry of the Earth's magnetic field can deviate significantly from a dipole, even at relatively low L shells and on the dayside magnetosphere. This study investigates the importance of including a realistic magnetic field geometry when computing plasma mass density from observed field line eigenfrequencies. A generalized version of the toroidal mode MHD standing wave equation is solved using the Tsyganenko (2002a, 2002b) empirical magnetic field model (T01). The results are compared to those found using a dipole. We find that assuming a dipole magnetic field geometry results in an overestimation of mass density. The overestimation is larger for more disturbed levels of geomagnetic activity. Our results have important implications for the inference of heavy ions in the magnetosphere. Namely, an increase in heavy ion concentration as a result of enhanced geomagnetic activity will be exaggerated unless the proper magnetic field geometry is taken into account when calculating mass density from field line eigenfrequencies.
Gravity wave influence on the global structure of the diurnal tide in the mesosphere and lower thermosphere
Authors: Ortland David A. , Alexander M. Joan
Published: August 2006

Observations of the diurnal tide from instruments aboard the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) explorer and from the Upper Atmosphere Research Satellite (UARS) show that the vertical wavelength of the tide is significantly shorter than what is predicted by tidal theory. The observed vertical structure of the tide can be reproduced in a mechanistic model by including gravity wave interaction. The model tide amplitude and phase are sensitive to the amplitude and phase of the diurnal component of momentum forcing that arises from gravity wave breaking. The phase of the momentum forcing relative to the tide determines whether the tide amplitude is increased or diminished by gravity wave forcing, while the amplitude of the momentum forcing determines how rapidly the tide phase will change with height. The momentum forcing profile is shaped by the structure of the gravity wave source spectrum. By comparing both the model tide amplitude and phase profiles to observations, we can provide constraints on both the gravity wave source spectrum that should be used in a gravity wave parameterization scheme and on the eddy diffusion that acts on the tide. We examine differences between the effects that two gravity wave schemes have on the tide. The role that gravity waves may play in producing tide variability is discussed in light of the results presented here.
Thermospheric density 2002–2004: TIMED/GUVI dayside limb observations and satellite drag
Authors: Emmert J. T. , Meier R. R. , Picone J. M. , Lean J. L. , Christensen A. B.
Published: August 2006

We use TIMED/GUVI dayside limb observations of thermospheric far ultraviolet (FUV) dayglow to infer height profiles of total mass density during the period 2002–2004. We compare these data with total mass density derived from drag‐induced changes in the orbits of satellites with perigee heights ranging from 200 to 600 km. To accommodate sampling differences, we compute the ratio of observed total mass density, filtered on a 3‐day timescale, to that predicted by the NRLMSISE‐00 empirical model. The GUVI densities are in good agreement with the orbit‐derived densities in the 300–500 km range, where the correlation of the two independent measurements is ∼0.68 and the relative bias is less than 5%, which is within the absolute uncertainty of the drag results. Of interest is a prolonged depletion of upper thermospheric density (relative to NRLMSIS) during July 2002, when densities from both techniques were 20–35% smaller than those predicted by NRLMSIS. Our results represent the first validation of absolute densities derived from FUV limb scanning.
Contributions of the solar ultraviolet irradiance to the total solar irradiance during large flares
Authors: Woods Thomas N. , Kopp Greg , Chamberlin Phillip C.
Published: August 2006

The solar X‐ray radiation varies more than other wavelengths during flares; thus solar X‐ray irradiance measurements are relied upon for detecting flare events as well as used to study flare parameters. There is new information about the spectral and temporal variations of flares using solar irradiance measurements from NASA's Solar Radiation and Climate Experiment (SORCE) and the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) missions. For one, the improved measurement precision for the total solar irradiance (TSI) measurements by the SORCE Total Irradiance Monitor (TIM) has enabled the first detection of flares in the TSI. These flare observations indicate a total flare energy that is about 105 times more than the X‐ray measurements in the 0.1–0.8 nm range. In addition, solar spectral irradiance instruments aboard TIMED and SORCE have observed hundreds of flare events in the 0.1 nm to 190 nm range. These solar ultraviolet measurements show that the ultraviolet irradiance changes during flares account for 50% or more of the flare variations seen in the TSI, with most of the ultraviolet contribution coming from the ultraviolet shortward of 14 nm. The remaining part of the flare energy is assumed to come from the wavelengths longward of 190 nm, typically only needing to be about 100 ppm increase for the largest flares. Another result is that the flare variations in the TSI have a strong limb darkening effect, whereby the flares near the limb indicate variations in the TSI being almost entirely from the ultraviolet shortward of 14 nm.
Stress‐induced brittle fragmentation of magmatic melts: Theory and experiments
Authors: Büttner Ralf , Dellino Pierfrancesco , Raue Hannes , Sonder Ingo , Zimanowski Bernd
Published: August 2006

The release of kinetic energy during explosive volcanic eruptions is a key parameter for hazard assessment and civil defense. The explosive production of volcanic ash by intensive fragmentation of magma and host rocks represents a substantial part of this energy. For cases of explosive eruption where predominantly host rock was fragmented (phreatomagmatic eruptions) to form the major part of volcanic ash, rock mechanical parameters could be measured and fragmentation energies assigned. In cases where most of the produced ash is of juvenile origin (magmatic eruptions) a general method for the determination of fragmentation energy is still lacking. In this article we introduce a thermodynamic approach that relates grain size data of the produced ash deposits to shear rates acting during the deformation of magma. With the use of a standardized fragmentation experiment the physical parameters needed to determine the specific fragmentation energy and deformation history were measured. The experiment was calibrated and tested with two case histories of the Campi Flegrei volcanic field (southern Italy). Both eruptions are classified as “most probable worst‐case scenarios” during the next period of activity, to be expected within the next 10–100 years. Using the experimentally determined specific fragmentation energies, the total mass of produced ash of each eruption, and assuming an energy dissipation as observed in the experiments, the total kinetic energy release of the worst‐case Campi Flegrei eruptive events to come were calculated with 25 and 40 kt TNT equivalent.
Channel flow and the development of parallel‐dipping normal faults
Authors: Nagel Thorsten J. , Buck W. Roger
Published: August 2006

In a series of numerical experiments, arrays of parallel‐dipping normal faults formed only if the model contained a thin viscous layer sandwiched between the brittle, faulted layer on top and a lower boundary that resisted vertical displacement. With this particular vertical stratification, parallel‐dipping faults developed even if the viscous layer had a shear‐stress‐free lower boundary condition. This observation contradicts previous studies relating parallel‐dipping normal faults to consistent horizontal shear stress in the brittle layer. We explain the formation of parallel‐dipping normal faults in our experiments through the properties of flow in a thin viscous channel and how this flow accommodates and delocalizes faulting in the brittle layer on top. First, for closely spaced normal faults, an array of parallel‐dipping faults minimizes the viscous work rate (dissipation) in the viscous layer as it minimizes the distance between sources and sinks in the flow pattern. Second, a thin layer of moderate viscosity leads to the required formation of closely spaced single faults. A highly viscous substratum tends to reflect faults at the base of the brittle layer and hence promotes the formation of a local graben at each necking site in the brittle layer. With lower viscosities, a thick layer or a floating lower boundary condition usually leads to the formation of widely spaced core complexes in the brittle layer. Our scheme can explain varying dip polarity along strike, which is observed in many rift systems and difficult to explain through consistent shear stress.
Statistical properties of seismic anisotropy predicted by upper mantle geodynamic models
Authors: Becker Thorsten W. , Chevrot Sebastien , Schulte‐Pelkum Vera , Blackman Donna K.
Published: August 2006

We study how numerically predicted seismic anisotropy in the upper mantle is affected by several common assumptions about the rheology of the convecting mantle and deformation‐induced lattice preferred orientations (LPO) of minerals. We also use these global circulation and texturing models to investigate what bias may be introduced by assumptions about the symmetry of the elastic tensor for anisotropic mineral assemblages. Maps of elasticity tensor statistics are computed to evaluate symmetry simplifications commonly employed in seismological and geodynamic models. We show that most of the anisotropy predicted by our convection‐LPO models is captured by estimates based on a best fitting hexagonal symmetry tensor derived from the full elastic tensors for the computed olivine:enstatite LPOs. However, the commonly employed elliptical approximation does not hold in general. The orientations of the best fitting hexagonal symmetry axes are generally very close to those predicted for finite strain axes. Correlations between hexagonal anisotropy parameters for P and S waves show simple, bilinear relationships. Such relationships can reduce the number of free parameters for seismic inversions if this information is included a priori. The match between our model predictions and observed patterns of anisotropy supports earlier, more idealized studies that assumed laboratory‐derived mineral physics theories and seismic measurements of anisotropy could be applied to study mantle dynamics. The match is evident both in agreement between predicted LPO at selected model sites and that measured in natural samples, and in the global pattern of fast seismic wave propagation directions.
Origin and significance of clay‐coated fractures in mudrock fragments of the SAFOD borehole (Parkfield, California)
Authors: Schleicher Anja M. , van der Pluijm Ben A. , Solum John G. , Warr Laurence N.
Published: August 2006

The clay mineralogy and texture of rock fragments from the SAFOD borehole at 3067 m and 3436 m measured depth (MD) was investigated by electron microscopy (SEM, TEM) and X‐ray‐diffraction (XRD). The washed and ultrasonically cleaned samples show slickenfiber striations and thin films of Ca‐K bearing smectite that are formed on polished fault surfaces, along freshly opened fractures and within adjacent mineralized veins. The cation composition and hydration behavior of these films differ from the Na‐montmorillonite of the fresh bentonite drilling mud, although there is more similarity with circulated mud recovered from 3479 m MD. We propose that these thin film smectite precipitates formed by natural nucleation and crystal growth during fault creep, probably associated with the shallow circulation of low temperature aqueous fluids along this shallow portion of the San Andreas Fault.
Observations of tropical precipitating clouds ranging from shallow to deep convective systems
Authors: Masunaga Hirohiko , Kummerow Christian D.
Published: August 2006

Regional and temporal variability in a broad spectrum of tropical precipitation systems is investigated in conjunction with the large‐scale environment. The analysis utilizes four storm categories (Shallow, Cumulus Congestus, Deep Stratiform, and Deep Convective) determined from Tropical Rainfall Measuring Mission (TRMM) measurements. Deep Stratiform and Deep Convective systems are found to be clearly correlated with large‐scale circulation deduced from a reanalysis data set, and are modulated by a distinct seasonal cycle over land. The Shallow category is practically the only component of tropical oceanic rainfall for cold sea surfaces, while it gives way to deeper systems as SST exceeds 28–29°C. The cloud horizontal scale of organized rainfall systems tends to be increasingly extensive relative to the raining portion as the system becomes larger. The present results are discussed in light of existing relevant studies.
Low geomagnetic field intensity during the Kiaman superchron: Thellier and microwave results from the Great Whin Sill intrusive complex, northern United Kingdom
Authors: Garcia Alexander S. , Thomas D. Neil , Liss Dirk , Shaw John
Published: August 2006

Coe‐Modified Thellier (CMT) and Microwave (MW) paleointensity experiments were conducted on samples from the multi‐phase late Carboniferous (ca. 301 Ma) to early Permian (ca. 270 Ma) Great Whin Sill complex. Statistically comparable results were obtained with both techniques from high quality data. Forty three samples (25 with CMT and 18 with MW) yielded mean paleointensity values of 12.0 ± 5.8 μT and 16.5 ± 8.2 μT for the early and late intrusive phases respectively, corresponding to VDMs of (1.6 ± 0.8) × 1022 and (2.1 ± 1.1) × 1022 Am2. When combined with previous data, the results suggest a generally low dipole moment during the KRS, reducing from ∼75% of the present value at 301 Ma to 20–27% of the present value later in the superchron. These data imply either a decoupling between processes controlling reversal rate and field strength, or a more complex, intriguing time‐lag relationship. More absolute palaeointensity results are needed to further evaluate these alternatives.
Magnitude estimation using the first three seconds P‐wave amplitude in earthquake early warning
Authors: Wu Yih‐Min , Zhao Li
Published: August 2006

Pd is the peak amplitude of displacement in the first three seconds after the arrival of the P wave. We investigated the attenuation of Pd with the hypocentral distance R in southern California as a function of magnitude M, and obtained the following relationship: log (Pd) = −3.463 + 0.729 × M − 1.374 × log (R) ± 0.305. Given an earthquake location determined by the P‐wave arrival times at stations close to the epicenter, this relationship can be used to define a so‐called “Pd magnitude” of earthquakes. Our result shows that for earthquakes in southern California the Pd magnitudes agree with the catalog magnitudes with a standard deviation of 0.18 for events less than magnitude 6.5. Therefore, Pd is a robust measurement for estimating the magnitudes of earthquakes and has practical application in earthquake early warning systems.
Upper mantle seismic structure beneath eastern Mexico determined from P and S waveform inversion and its implications
Authors: Gao Wei , Matzel Eric , Grand Stephen P.
Published: August 2006

We present compressional (P) and shear (S) wave seismic velocity models for the upper mantle beneath southeastern Mexico derived from waveform inversion of triplicated seismic phases. The seismic waveform data produced by an earthquake located near the Mexico‐Guatemala border were recorded by the La Ristra passive seismic array. The La Ristra seismic array consists of 54 broadband seismometers arranged linearly from west Texas to southeastern Utah. The orientation of the La Ristra array is nearly along the great circle from the event, and the distance (18.5°–26.5°) of the seismic array from southern Mexico is such that the data are ideal for investigating localized seismic structure of the upper mantle. Previous tomography and receiver function studies provide a priori knowledge of receiver‐side crustal and upper mantle structure from which static adjustments were made to the seismic data. The waveforms were inverted for mantle velocity from 40 to 1000 km depth using a conjugate gradient algorithm. In the inversion, we evaluated a suite of starting models with different depths of the 410 km and 660 km discontinuities and varying velocity gradients. The best fitting models have velocity increases across the 410 km discontinuity of 6.2% and 7.3% for P and S wave velocities, respectively. The velocity jump across the 660 km discontinuity was found to be 3.3% for P waves and 6.3% for S waves. The size of the upper mantle discontinuities that we find are more in agreement with a pyrolite composition than standard reference models imply. A common feature of the best fitting models is a low‐velocity zone above the 410 km discontinuity that is more prominent in the shear velocity model than the compressional velocity model. This feature may be due to partial melting induced by water release from the transition zone. The overall jump in velocity at 410 km is also larger than in previously published models with a lower gradient below. In addition, the P wave data require a small discontinuity at 490 km depth that is not resolved in the S data. Finally, the S wave data require an unusually high gradient beginning at about 600 km depth extending to the 660 km discontinuity. This feature may be due to a thermal and/or mineralogic anomaly due to a flat lying slab beneath eastern Mexico.
Impaired Wound Healing after Cerebral Hypoxia—Ischemia in the Diabetic Mouse
Authors: Kumari Rashmi , Willing Lisa B , Krady J Kyle , Vannucci Susan J , Simpson Ian A
Published: August 2006

Impaired peripheral wound healing is a hallmark of diabetis pathology and has been attributed to compromised macrophage activation. Stroke is another component of diabetic pathology, with increased tissue infarction and worsened recovery although the mechanisms remain unresolved. In this study, we investigated whether a compromised glial/macrophage response might contribute to cerebral hypoxic-ischemic (H/I) brain damage in diabetic ( db/ db), relative to their normoglycemic db/+ mice. Hypoxia-ischemia was induced in 8-week-old male db/ db and db/+ mice by the ligation of right common carotid artery followed by systemic hypoxia (8% O2: 92% N2) for 17 mins. Mice were killed at specific intervals of reperfusion/recovery and the brains analyzed by in situ hybridization or total RNA isolation. In situ hybridization using bfl-1 (microglia) and glial fibrillary acidic protein (GFAP) (astrocytes) revealed expression of both bfl-1 and GFAP in the ipsilateral hemisphere at 4 h in the db/+ mice, which was delayed and minimal in the db/ db mice. RNase protection assays showed a robust increase in expression of the proinflamatory cytokines tumor necrosis factor-α (TNFα), interleukin-1 IL-1α, and IL-1β mRNA in the db/+ mice at 6 to 8 h of reperfusion peaking at 8 to 12 h; in db/ db mice expression was markedly delayed and diminished. Real-time-polymerase chain reaction (RT-PCR) confirmed the reduced and delayed expression TNFα, IL-1α, IL-1β, and the growth factors insulin-like growth factor-1 and ciliary neurotrophic factor in the db/ db mice; enzyme-linked immunosorbent assays confirmed the reduced and delayed translation of IL-1β protein. These findings suggest that a compromised inflammatory response may underlie the greater infarct associated with diabetic db/ db mice compared with their nondiabetic littermates following a hypoxic/ischemic insult.
Less Neurogenesis and Inflammation in the Immature than in the Juvenile Brain after Cerebral Hypoxia-Ischemia
Authors: Qiu Lin , Zhu Changlian , Wang Xiaoyang , Xu Falin , Eriksson Peter S , Nilsson Michael , Cooper-Kuhn Christiana M , Kuhn H Georg , Blomgren Klas
Published: August 2006

The effects of hypoxia-ischemia (HI) on proliferation and differentiation in the immature (postnatal day 9) and juvenile (postnatal day 21) mouse hippocampus were investigated by injecting bromodeoxyuridine (50 mg/kg) daily for 7 days after the insult and evaluating the labeling 5 weeks after HI. Phenotypic differentiation was evaluated using NeuN, Iba1, APC, and S100β as markers of neurons, microglia, oligodendrocytes, and astrocytes, respectively. The basal proliferation, in particular neurogenesis, was higher in the immature than in the juvenile hippocampus. Hypoxia-ischemia did not increase neurogenesis significantly in the immature dentate gyrus (DG), but it increased several-fold in the juvenile brain, reaching the same level as in the normal, noninjured immature brain. This suggests that the immature hippocampus is already working at the top of its proliferative capacity and that even though basal neurogenesis decreased with age, the injury-induced generation of new neurons in the juvenile hippocampus could not increase beyond the basal level of the immature brain. Generation of glial cells of all three types after HI was significantly more pronounced in the cornu ammonis of the hippocampus region of the juvenile hippocampus. In the DG, only microglia production was greater in the juvenile brain. Increased microglia proliferation correlated with increased levels of the proinflammatory cytokines MCP-1 and IL-18 3 days after HI, indicating that the inflammatory response is stronger in the juvenile hippocampus. In summary, contrary to what has been generally assumed, our results indicate that the juvenile brain has a greater capacity for neurogenesis after injury than the immature brain.
Feasibility of Velocity Selective Arterial Spin Labeling in Functional MRI
Authors: Wu Wen-Chau , Wong Eric C
Published: August 2006

Arterial spin labeling (ASL) magnetically inverts or saturates the spins in arterial blood and uses them as endogenous tracers. Conventionally, the tagging band is upstream or nonselective to the target slices. In the brain, ASL-based functional magnetic resonance imaging (fMRI) has been shown to detect activation better localized in gray matter than blood oxygenation level dependent contrast. More recently, velocity selective-ASL (VS-ASL) was proposed to tag spins according to their flow velocity. One desirable characteristic of VS-ASL is its capability to generate tags sufficiently close to the target slices and thereby circumvent the complication of non-zero transit delay. In this study, we investigate the feasibility of VS-ASL in fMRI by comparing it with a conventional ASL method (PICORE). The results from the visual cortex of healthy volunteers show that VS-ASL and PICORE have comparable spatial specificity in detecting the flow change induced by neuronal activity. Velocity selective-arterial spin labeling can further distinguish the contribution from different flow directions but spurious elevation of fractional signal change may occur when the VS tagging is applied off the direction of blood supply. The flow reaches the vicinity of perfusion at a cutoff velocity ( Vc) of 2 cm/sec whereas the activation exclusively detected by Vc = 4 cm/sec implies the arteriolar response to the neuronal activity and a respondent vessel diameter up to 240 μm. Velocity selective imaging can remove intravascular signal from the vessels where the flow velocity is above Vc.
Mast Cell Blocking Reduces Brain Edema and Hematoma Volume and Improves Outcome after Experimental Intracerebral Hemorrhage
Authors: Strbian Daniel , Tatlisumak Turgut , Ramadan Usama Abo , Lindsberg Perttu J
Published: August 2006

Intracerebral hemorrhage (ICH) is associated with high mortality and disability, and there is no widely approved clinical therapy. Poor outcome after ICH results mostly from a mass effect owing to enlargement of the hematoma and brain swelling, leading to displacement and disruption of brain structures. Cerebral mast cells (MC) are resident inflammatory cells that are located perivascularly and contain potent vasoactive, proteolytic, and fibrinolytic substances. We previously found pharmacological MC stabilization and genetic MC deficiency to be associated with up to 50% reduction of postischemic brain swelling in rats. Here, we studied the role of MC and MC stabilization in ICH using in vivo magnetic resonance imaging and ex vivo digital imaging for calculating brain edema and hematoma volume. In a rat ICH model of autologous blood injection into the basal ganglia, four groups of Wistar rats received either saline or sodium cromoglycate (MC stabilizer, two groups) or compound 48/80 (MC degranulator). Evaluated 24 h later, MC stabilization had resulted in highly significantly better neurologic scores ( P < 0.001), decrease mortality ( P = 0.002), less brain swelling ( P < 0.001), and smaller hematoma volume growth ( P < 0.001) compared with saline and compound 48/80. Moreover, to support our hypothesis, we induced ICH in MC-deficient rats and their wild-type littermates (WT). MC-deficient rats responded with significantly better neurologic scores ( P < 0.001), decrease mortality (0% versus 25%), less brain swelling ( P < 0.05), and smaller hematoma growth ( P < 0.05) than WT. The role of MC deserves a close evaluation as a potential target in the development of novel forms of ICH therapy.