bluuebunny/crossref_metadata_2025 huggingface dataset:
Bubble rise in a liquid with a surfactant gas, in particular carbon dioxide
Authors: HARPER J. F.
Published: May 2007

When a gas bubble rises in a surfactant solution, the velocity field and the distribution of surfactant affect each other. This paper gives the theory for small Reynolds and internal Péclet numbers if the surfactant is gaseous or volatile, if its mass flux across the bubble and around its surface dominates its mass flux through the bulk liquid, and if slowness of both adsorption and convective diffusion must be allowed for.

The theory is tested on the experiments of Kelsall et al. (J. Chem. Soc. Faraday Trans., vol. 92, 1996, p. 3879). Their bubbles rose as expected in a pure liquid until the apparatus was opened to the atmosphere. That significantly slowed the bubbles down. The effect is so sensitive to small concentrations of slowly adsorbing or reacting surfactants that atmospheric carbon dioxide could have caused it, even though it alters the equilibrium surface tension by less than four parts per million in pure air.

There are still unexplained discrepancies between experiment and theory. Additional experiments are suggested that would help to explain them.
Energy transfer in turbulent polymer solutions
Authors: CASCIOLA C. M. , DE ANGELIS E.
Published: May 2007

The paper addresses a set of new equations concerning the scale-by-scale balance of turbulent fluctuations in dilute polymer solutions. The main difficulty is the energy associated with the polymers, which is not of a quadratic form in terms of the traditional descriptor of the micro-structure. A different choice is however possible, which, at least for mild stretching of the polymeric chains, directly leads to an L2 structure for the total free-energy density of the system thus allowing the extension of the classical method to polymeric fluids. On this basis, the energy budget in spectral space is discussed, providing the spectral decomposition of the energy of the system. New equations are also derived in physical space, to provide balance equations for the fluctuations in both the kinetic field and the micro-structure, thus extending, in a sense, the celebrated Kármán–Howarth and Kolmogorov equations of classical turbulence theory. The paper is limited to the context of homogeneous turbulence. However the necessary steps required to expand the treatment to wall-bounded flows of polymeric liquids are indicated in detail.
Direct numerical simulations of vortex rings at ReΓ = 7500
Authors: BERGDORF MICHAEL , KOUMOUTSAKOS PETROS , LEONARD ANTHONY
Published: May 2007

We present direct numerical simulations of the turbulent decay of vortex rings with ReΓ = 7500. We analyse the vortex dynamics during the nonlinear stage of the instability along with the structure of the vortex wake during the turbulent stage. These simulations enable the quantification of vorticity dynamics and their correlation with structures from dye visualization and the observations of circulation decay that have been reported in related experimental works. Movies are available with the online version of the paper.
Pilot comparison between potassium titanyl phosphate laser and bipolar radiofrequency in paediatric tonsillectomy
Authors: Hegazy H M , Albirmawy O A , Kaka A H , Behiry A S
Published: May 2007

Objectives:

To compare the advantages and disadvantages of potassium titanyl phosphate laser with those of bipolar radiofrequency techniques, in paediatric tonsillectomy.

Study design:

Prospective, randomised, clinical study.

Patients and methods:

From July 2004 to April 2006, 80 patients aged between 10 and 15 years, with tonsillectomy planned for chronic tonsillitis, were included in the study. Children were prospectively randomised into two equal groups: potassium titanyl phosphate laser tonsillectomy and bipolar radiofrequency tonsillectomy. Operative time and intra-operative blood loss were recorded. Patients were scheduled for follow up during the first, second and fourth post-operative weeks. They were asked to record their pain and discomfort on a standardised visual analogue scale, from zero (no pain) to 10 (severe pain). Post-operative complications were also recorded and managed.

Results:

The potassium titanyl phosphate laser group showed a slightly longer operative time (mean 12 minutes) than the bipolar radiofrequency group (mean 10 minutes). Intra-operative blood loss was significantly less in the potassium titanyl phosphate laser group (mean 21 cm3) than in the bipolar radiofrequency group (mean 30 cm3). In the first week, post-operative pain scores were less in the potassium titanyl phosphate laser group than in the bipolar radiofrequency group (means 7.5 and 8.5, respectively). However, in the second week pain scores increased more in the potassium titanyl phosphate laser group than in the bipolar radiofrequency group (means 8.5 and 6, respectively). In the fourth week, both groups showed equal and nearly normal pain scores. No case of reactionary post-tonsillectomy haemorrhage was recorded in either group. Only one case of secondary post-tonsillectomy haemorrhage was recorded, in the potassium titanyl phosphate laser group (2.5 per cent), managed conservatively.

Conclusion:

Both the potassium titanyl phosphate and the bipolar radiofrequency techniques were safe and easy to use for tonsillectomy, with reduced operative time, blood loss and complication rates and better post-operative general patient condition. Potassium titanyl phosphate laser resulted in reduced operative bleeding and immediate post-operative pain, compared with the bipolar radiofrequency technique. However, potassium titanyl phosphate laser required slightly more operative time and caused more late post-operative pain than the bipolar radiofrequency technique. The low rate of recorded complications showed that both techniques cause little damage to the tonsillar bed during dissection, thus minimising complications.
Non-recurrent laryngeal nerve related to thyroid surgery: report of three cases
Authors: Page C , Monet P , Peltier J , Bonnaire B , Strunski V
Published: May 2007

Purpose of the study:

We aimed to highlight a rare anatomical variation involving the recurrent laryngeal nerve, and to emphasise its implications for thyroid surgery.

Materials and methods:

Over a period of 13 years, 993 patients underwent thyroid surgery; 1557 recurrent laryngeal nerves (887 on the right side) were exposed.

Results:

Three non-recurrent laryngeal nerves were found on the right side, associated with a retro-oesophageal subclavian artery. One case was suspected before surgery.

Discussion:

Several variations in the path and branches of the recurrent laryngeal nerve have been reported in the literature. The frequency of occurrence of a non-recurrent laryngeal nerve is about 1 per cent, for patients undergoing thyroid surgery. Other surgically relevant anatomical variations of the recurrent laryngeal nerve include associations with the inferior thyroid artery and the presence of nerve branches.

Conclusion:

The recurrent laryngeal nerve must be carefully dissected and totally exposed during thyroid surgery in order to best preserve its function. Moreover, the thyroid surgeon must be aware of the existence of anatomical variations, which are not as rare as one may think.
Acute disseminated encephalomyelitis after mastoid surgery in a child
Authors: Khan N A , Bhalla R K , de Goede C G E L , Rothera M P , Ismayl O
Published: May 2007

We present a case of acute disseminated encephalomyelitis after mastoid surgery in an 11-year-old child. The aim of this paper is to increase awareness about a previously unreported and an unusual neurological complication of cholesteatoma and mastoid surgery.
Explicit diagonalization of the Markov form on the
Temperley–Lieb algebra
Authors: GENAUER JOSH , STOLTZFUS NEAL W.
Published: May 2007

In a fundamental paper in 1984, Vaughan Jones developed his new polynomial
invariant of knots using a Markov trace on the Temperley–Lieb
algebra. Subsequently, Lickorish used the associated bilinear pairing to
provided an alternative proof for the existence of the 3-manifold invariants of
Witten, Reshetinkin and Turaev. A key property of this form is the
non-degeneracy of this form except at the parameter values
±2cos(π/(n+1)) [7]. Ko
and Smolinsky derived a recursive formula for the determinants of specific
minors of Markov's form, establishing the needed non-degeneracy
[6]. In this paper,
we define a triangular change of basis in which the form is diagonal and
explicitly compute the diagonal entries of this matrix as products of quotients
of Chebyshev polynomials, corroborating the determinant computation of Ko and
Smolinsky. The method of proof employs a recursive method for defining the
required orthogonal basis elements in the Temperley–Lieb algebra,
similar in spirit to Jones' and Wenzl's recursive formula
for a family of projectors in the Temperley–Lieb algebra. We define a
partial order on the non-crossing chord diagram basis and give an explicit
formula for a recursive construction of an orthogonal basis, via a recursion
over this partial order. Finally we relate this orthogonal basis to bases
constructed using the calculus of trivalent graphs developed by Kauffman and
Lins [5].
A strict totally coordinatized version of Kapranov and Voevodsky's 2-category 2Vect
Authors: ELGUETA JOSEP
Published: May 2007

In this paper we describe the 2-category 2Mat of 2-matrices, i.e., a strict totally coordinatized version of the 2-category 2Vect of Kapranov and Voevodsky finite dimensional 2-vector spaces, analogous to the category Mat of matrices which appears as the coordinatized version of the category Vect of finite dimensional vector spaces. In particular, explicit formulas for the composition of 1-morphisms and the two compositions between 2-morphisms are given.
Essential norm estimates of weighted composition operators between Bergman spaces on strongly pseudoconvex domains
Authors: ČUČKOVIĆ ŽELJKO , ZHAO RUHAN
Published: May 2007

We give estimates of the essential norms of weighted composition operators acting between Bergman spaces on strongly pseudoconvex domains. We also characterize boundedness and compactness of these operators.
Quantum stochastic operator cocycles via associated semigroups
Authors: LINDSAY J. MARTIN , WILLS STEPHEN J.
Published: May 2007

A recent characterisation of Fock-adapted contraction operator stochastic cocycles on a Hilbert space, in terms of their associated semigroups, yields a general principle for the construction of such cocycles by approximation of their stochastic generators. This leads to new existence results for quantum stochastic differential equations. We also give necessary and sufficient conditions for a cocycle to satisfy such an equation.
A Whitehead–Ganea approach for proper Lusternik–Schnirelmann category
Authors: GARCÍA–CALCINES J. M. , GARCÍA–DÍAZ P. R. , MAS A. MURILLO
Published: May 2007

We establish Whitehead and Ganea characterizations for proper LS-category. We use the embedding of the proper category into the exterior category, and construct in the latter a suitable closed model structure of Strøm type. Then, from the axiomatic LS-category arising from the exterior homotopy category we can recover the corresponding proper LS invariants. Some applications are given.
On the topology defined by Thurston's asymmetric metric
Authors: PAPADOPOULOS ATHANASE , THÉRET GUILLAUME
Published: May 2007

We establish some properties of Thurston's asymmetric metric L on the Teichmüller space ${\cal T}_{\frak{g},\frak{n}}$ of a surface of genus $\frak{g}$ with $\frak{n}$ punctures and with negative Euler characteristic. We study convergence of sequences of elements in ${\cal T}_{\frak{g},\frak{n}}$ in the sense of L, as well as sequences that tend to infinity in ${\cal T}_{\frak{g},\frak{n}}$. We show that the topology that the asymmetric metric L induces on Teichmüller space is the same as the usual topology. Furthermore, we show that L satisfies the axioms of a (not necessarily symmetric) metric in the sense of Busemann and conclude that L is complete in the sense of Busemann.
Brunnian links, claspers and Goussarov–Vassiliev finite type invariants
Authors: HABIRO KAZUO
Published: May 2007

Goussarov and the author independently proved that two knots in S3 have the same values of finite type invariants of degree <n if and only if they are Cn-equivalent, which means that they are equivalent up to modification by a kind of geometric commutator of class n. This property does not generalize to links with more than one component.

In this paper, we study the case of Brunnian links, which are links whose proper sublinks are trivial. We prove that if n ≥ 1, then an (n+1)-component Brunnian link L is Cn-equivalent to an unlink. We also prove that if n ≥ 2, then L can not be distinguished from an unlink by any Goussarov–Vassiliev finite type invariant of degree <2n.
The horofunction boundary of finite-dimensional normed spaces
Authors: WALSH CORMAC
Published: May 2007

We determine the set of Busemann points of an arbitrary finite-dimensional normed space. These are the points of the horofunction boundary that are the limits of “almost-geodesics”. We prove that all points in the horofunction boundary are Busemann points if and only if the set of extreme sets of the dual unit ball is closed in the Painlevé–Kuratowski topology.
Site fidelity of Weddell seals: the effects of sex and age
Authors: Cameron Michael F. , Siniff Donald B. , Proffitt Kelly M. , Garrott Robert A.
Published: May 2007

Site fidelity is believed to be an important life history strategy for Weddell seals (Leptonychotes weddellii), that return to traditional breeding colonies each spring. We examined four hypotheses concerning their fidelity to these colonies: 1) fidelity is stronger to natal sites (natal fidelity) than to other sites, 2) females exhibit greater site fidelity than males, 3) site fidelity for both sexes increases with age, 4) site fidelity in adult females is related to their reproductive status and their total number of offspring. Analysis of a long-term tagging database from McMurdo Sound did not support hypotheses 1 and 2. Although animals did express fidelity to specific sites over their lifetime (χ2 tests, P < 0.05), fidelity to natal colonies was lower than to other sites (χ2 test, P < 0.05). There were no differences in site fidelity between males and females (χ2 tests, P > 0.05). Hypothesis 3 was supported. Since the probability of a returning seal occupying the same colony as the previous year increased with age among both sexes to about age 12. Finally, in support of hypothesis 4, females with a higher degree of site fidelity were more likely to both have a higher reproductive rate and return to a site where they have previously given birth.
A new approach to selecting Marine Protected Areas (MPAs) in the Southern Ocean
Authors: Harris Jane , Haward Marcus , Jabour Julia , Woehler Eric J.
Published: May 2007

Conservation of the high seas marine environment poses a significant challenge to policy-makers and managers. Marine conservation efforts are often hindered by the lack of data and the difficulties in addressing multiple, and typically conflicting uses. The majority of extant Marine Protected Areas (MPAs) are in coastal or tropical regions within national jurisdiction. Conservation of high seas MPAs has emerged on the international agenda as a critical issue requiring the application of novel approaches, international cooperation and political will. Knowledge and understanding of the marine environment and data on marine biodiversity are all typically limited for the high seas, and the use of surrogates to assist in the identification of areas of high conservation value is one possible mechanism to address and potentially overcome these limitations. Drawing upon a database spanning more than 20 years and containing approximately 140 000 records of seabird sightings at sea, this study assesses the potential use of seabirds as surrogates for marine biodiversity in the Indian sector of the Southern Ocean. At-sea ranges, species diversity and the distributions of endangered species may be appropriate selectors or filters to identify areas with high conservation values. Integrating policy with science provides an appropriate mechanism to identify and prioritise MPAs in the Southern Ocean.
Adaptive evolution of the heat-shock response in the Antarctic psychrophilic ciliate, Euplotes focardii: hints from a comparative determination of the hsp70 gene structure
Authors: La Terza Antonietta , Passini Valerio , Barchetta Sabrina , Luporini Pierangelo
Published: May 2007

The Antarctic psychrophilic ciliate Euplotes focardii manifests a dramatic reduction in the activation of its hsp70 gene in response to a heat-shock, while oxidative and chemical stresses activate the transcription of this gene to appreciable extents. To investigate the genetic causes of this eccentric behaviour of E. focardii in the hsp70 gene transcription activation, we carried out a comparative structural analysis of this gene between E. focardii and another Antarctic Euplotes, E. nobilii, which manifests a psychrotrophic behaviour and an inducible thermal response. No substantial difference was detected in the organization of the hsp70 5' promoter region, both species bearing canonical regulatory cis-acting elements deputed to bind transcriptional trans-activating factors. Adenine-rich elements favouring mRNA degradation were instead detected in the hsp70 3' regulatory region of E. nobilii, but not in that of E. focardii. These observations lend further support to the hypothesis that the causes of the Euplotes focardii unresponsiveness to thermal stress resides in some structural, or functional modifications of transcriptional trans-activating factors.
The Root effect – a structural and evolutionary perspective
Authors: Verde Cinzia , Vergara Alessandro , Giordano Daniela , Mazzarella Lelio , Di Prisco Guido
Published: May 2007

Haemoglobin carries oxygen from the environment to tissues; in vertebrates, it is contained in specialized cells, called erythrocytes. Over the last century, the study of the chemical properties of this haemoprotein has provided a wealth of information. One of its most important and ancient physiological features is the Root effect, found in many teleost fish (and some amphibians). The Root effect corresponds to an extreme pH sensitivity and can be described as an exaggerated Bohr effect: it dictates to what extent the oxygen tension can be raised in acid-producing tissues. It is likely that the eye choroid rete represents the most ancient anatomical structure associated with the presence of Root effect haemoglobins. This review describes our overall understanding of the molecular properties, biological occurrence, physiological role and evolutionary origin of Root effect haemoglobins. The current knowledge of the structural properties of Root effect haemoglobins is discussed in the light of recent results obtained on the haemoglobins of the coldadapted notothenioids Trematomus newnesi and T. bernacchii.
Magazines for children and young people and the links to Internet food marketing: a review of the extent and type of food advertising
Authors: Cowburn Gill , Boxer Anna
Published: May 2007

Objective

To examine the nature of the link between food advertising in UK magazines aimed at children and young people and Internet food marketing, to establish whether consideration should be given to tightening existing controls.

Design

A review and descriptive analysis of food advertising found in a sample of the top five magazine titles aimed at a range of ages of children and young people between November 2004 and August 2005 and of the Internet food marketing sites to which readers were directed.

Results

Food advertising appeared as ‘cover-mount’ free gifts and as part of the main bound issue. Children aged 6–10 years were the most frequent recipients of food-based free gifts, all of which were confectionery. No food advertising was found in magazines aimed at pre-school children and it formed a small percentage of total advertising in the magazines aimed at children of school age and above. Most food advertisements were for ‘less healthy’ foods, although advertisements for ‘healthier’ food products did appear infrequently. Almost half of food advertisements directed readers towards Internet food marketing sites. We found evidence that these sites are using at least some of the ‘marketing tricks’ which have been identified as a cause for concern.

Conclusions

Proposed restrictions on broadcast media may lead to more food advertising via other non-broadcast means. We suggest monitoring the effect of such changes in print and online advertising and that consideration be given to restricting marketing techniques used on websites aimed at children and young people.
Improving the quality of life of geriatric cancer patients with a
structured multidisciplinary intervention: A randomized controlled
trial
Authors: LAPID MARIA I. , RUMMANS,. TERESA A. , BROWN PAUL D. , FROST MARLENE H. , JOHNSON MARY E. , HUSCHKA MASHELE M. , SLOAN JEFF A. , RICHARDSON JARRETT W. , HANSON JEAN M. , CLARK MATTHEW M.
Published: May 2007

Objective: To examine the potential impact of elderly age on
response to participation in a structured, multidisciplinary
quality-of-life (QOL) intervention for patients with advanced cancer
undergoing radiation therapy.

Methods: Study design was a randomized stratified, two group,
controlled clinical trial in the setting of a tertiary care comprehensive
cancer center. Subjects with newly diagnosed cancer and an estimated
5-year survival rate of 0%–50% who required radiation therapy were
recruited and randomly assigned to either an intervention group or a
standard care group. The intervention consisted of eight 90-min sessions
designed to address the five QOL domains of cognitive, physical,
emotional, spiritual, and social functioning. QOL was measured using
Spitzer uniscale and linear analogue self-assessment (LASA) at baseline
and weeks 4, 8, and 27.

Results: Of the 103 study participants, 33 were geriatric (65
years or older), of which 16 (mean age 72.4 years) received the
intervention and 17 (mean age 71.4 years) were assigned to the standard
medical care. The geriatric participants who completed the intervention
had higher QOL scores at baseline, at week 4 and at week 8, compared to
the control participants.

Significance of results: Our results demonstrate that
geriatric patients with advanced cancer undergoing radiation therapy will
benefit from participation in a structured multidisciplinary QOL
intervention. Therefore, geriatric individuals should not be excluded from
participating in a cancer QOL intervention, and, in fact, elderly age may
be an indicator of strong response to a QOL intervention. Future research
should further explore this finding.
An exploration of the utility of hypnosis in pain management among rural pain patients
Authors: THORNBERRY THOMAS , SCHAEFFER JENNIFER , WRIGHT PETER D. , HALEY MINDI C. , KIRSH KENNETH L.
Published: May 2007

Objective:Hypnosis is an adjunctive, noninvasive treatment with few side effects that can be useful in the management of chronic pain. However, it has fallen into disfavor in recent years and is often perceived by physicians as simple charlatanism. We evaluated the efficacy of this treatment as used clinically in a large, mostly rural, pain management center.

Methods:We conducted a chart review of 300 pain patients from the Pain Treatment Center of the Bluegrass who had undergone hypnosis for their pain concerns. A chart audit tool was developed consisting of basic demographics, pre- and posthypnosis pain ratings, a rating of relaxation achieved posthypnosis, and scores on the Beck Depression Inventory, Perceived Disability Scale, and the Pain Anxiety Symptom Scale.

Results:The sample consisted of 79 men (26.3%) and 221 women (73.7%) with a mean age of 46.3 years (SD= 9.9, range = 19–78). Pain levels recorded pre- and posthypnosis revealed significant improvement as a result of the intervention (mean difference = 2.5,t(1,298) = 25.9,p< .001). Patients reported an average of 49.8% improvement in relaxation level posthypnosis (SD= 24.2%) and had a mean score of 19.0 on the Beck Depression Inventory (SD= 9.9), indicating moderate levels of depression. Also, patients saw themselves as severely disabled regarding their ability to engage in physical (8.3/10) or job-related (7.7/10) activities. Attempts to identify predictors of hypnosis success were not fruitful with one exception. “Poor” responders to hypnosis reported greater levels of perceived dysfunction in their sexual functioning compared to the “good” responders,F(1,187) = 7.2,p< .01.

Significance of results:Hypnosis appears to be a viable adjunct for pain management patients, including those from rural and relatively disadvantaged backgrounds. Prospective trials are needed to examine the utility of this modality in end-of-life and palliative care patients.
The loneliness experience of the dying and of those who care for
them
Authors: ROKACH AMI , MATALON RAAN , SAFAROV ARTEM , BERCOVITCH MICHAELA
Published: May 2007

Objective: The study compared the qualitative aspects of the
loneliness experience of the dying, their caregivers, and the general
population.

Method: The patients were recruited in an oncological hospice
in Israel, and, despite being on their deathbed, agreed to participate in
the study. Thirty-seven cancer-stricken patients, 78 caregivers, and 128
participants from the general population volunteered to partake in the
study. They answered, anonymously, a 30-item questionnaire and were asked
to endorse those items that described their experience of loneliness.

Results: Results suggested that the three populations did,
indeed, differ in their experience of loneliness. More specifically, dying
patients and their caregivers had significantly higher subscale scores on
the Growth and Discovery and the Self-alienation subscales than the
general population did. It was also found that the number of
hospitalization days was significantly negatively correlated to the
Emotional Distress and Self-alienation subscales.

Significance of results: The present results indicate that
loneliness is experienced differently in or out of the hospice and by the
dying patient, his or her caregiver, and the general population. This may
be the first study to examine the qualitative aspects of the loneliness
experienced by the dying and by their caregivers. More research is needed
to replicate the present study, using larger samples.
A review of methylnaltrexone, a peripheral opioid receptor
antagonist, and its role in opioid-induced constipation
Authors: SHAIOVA LAUREN , RIM FAYE , FRIEDMAN DEBORAH , JAHDI MARYAM
Published: May 2007

Objectives: Opioid medications are frequently used in pain
and palliative care patients with malignancy to manage symptoms such as
pain and dyspnea. However, opiates are associated with various side
effects. Constipation is a particularly problematic and common side effect
of opioid pharmacology. Opioid antagonists have been studied in the
management of opioid-induced constipation. Methylnaltrexone (MNTX) is a
peripheral opioid antagonist currently under clinical investigation. It
offers the potential to reverse undesirable side effects without reversing
analgesia.

Methods: This article attempts to review existing clinical
data, focusing on antagonism of opioid-induced adverse effects on the
gastrointestinal system.

Results: MNTX seems to be well tolerated with limited or
transient side effects. MNTX has been shown to improve oral-cecal transit
times in opioid treated patients, induce laxation in chronic opioid users,
and neither reverses the analgesic effects of morphine nor cause
withdrawal symptoms.

Significance of results: Larger clinical trials of MNTX are
still necessary to support its use as a standard for treatment of
opioid-induced constipation.
Empathy and the failure to treat pain
Authors: PASSIK STEVEN D. , BYERS KAREN , KIRSH KENNETH L.
Published: May 2007

We set out to discuss the psychological barriers that exist in the
treatment of pain. Specifically, we argue that clinicians have several
innate mechanisms at play that can hinder their judgment and lead to
erroneous assumptions about their patients. Issues are discussed from
social psychological and psychodynamic perspectives. A focus is placed on
the issue of empathy and how this, too, can act as a barrier to rational
judgment when evaluating patients. In the face of growing scrutiny on pain
management in the United States, it is important to understand the
barriers to providing care that already exist on an intrinsic level.
Through the exploration of these barriers, clinicians might be better able
to reflect on their own practice. Ultimately, we hope to push forward an
agenda of rational therapy in pain management that utilizes safeguards
against abuse and addiction while also preserving treatment modalities for
patients in need of services.
A panacea of general practice
Authors: DABSCHECK ADRIAN
Published: May 2007

As a general practitioner with an interest in palliative medicine,
occasionally patients with end-stage malignancies are referred to me. For
these people the search for a panacea is well and truly over. Rather than
searching for a cure for cancer they are now mostly searching for control
of their “pain,” with all that that implies. One of my roles
is to protect my patients from those peddling a panacea who in the process
may impose burdensome costs, be they physical, psychological, or
financial. The motives of those selling a “cure” may be
altruism or greed, or indeed both.
After you've gone
Authors: RODRIGUEZ JOSETTE
Published: May 2007

There are certain things that you learn about people when you sleep in
their beds, eat from their cupboards, commiserate with their family and
friends. There are things that we waltz around and others that are
apparent: that you were good, and raised your son with the utmost care.
That you loved your husband. That you loved being a wife and mother.
Stone Tears
Authors: Neimeyer Robert
Published: May 2007

Stone Tears.
La mesure échographique de l'épaisseur de l'Intima-Media de l'artère carotide commune: Marqueur précoce de l'athérosclérose
Authors: Tutta
Published: May 2007

Depuis 1986, après les travaux du groupe de Pignoli en Italie, la mesure échographique de l'épaisseur de l'intima-media (IMT) de l'artère carotide est considérée comme un outil très important pour la stratification du risque cardiovasculaire dans les études tant épidémiologiques que pharmacologiques. Après 20 ans d'améliorations technologiques dans le domaine des ultrasons et des techniques d'acquisition informatisées semiautomatiques, la mesure standardisée de L'IMT est actuellement possible et bien codifiée grâce au consensus élaboré et ensuite publié suite aux réunions d'experts à Mannheim-Brussels 2004–2006. L'analyse in vivo de l'IMT de l'artère carotide est certainement la première étape pour la détermination précoce de la formation de l'athérosclérose même avant que des lésions telles que les plaques soient identifiables. Tout particulièrement dans les situations de sujets à haut risque cardiovasculaire la mesure de l'IMT peut aider à la décision de l'introduction de traitements médicamenteux «aggressifs» même en prévention primaire.
Theoretical constraints on true polar wander
Authors: Tsai Victor C. , Stevenson David J.
Published: May 2007

For the present geologic epoch, true polar wander (TPW) is relatively small, but simple theoretical considerations suggest that it could have been larger in other epochs. In this work, we use scaling arguments to assess the qualitative behavior of TPW and a simple Maxwell model to analytically describe how changes in mass anomalies translate into TPW. Unlike previous work, we derive simple analytical estimates of TPW based on the characteristic amplitudes and timescales for changes in the moment of inertia. We find estimates for both the amplitude and speed of TPW as a function of Earth properties. The following four main factors influence how large the maximum TPW can be: the (geological) timescale over which the desired TPW occurs τTPW, the viscosity structure of the mantle which yields a weighted average viscosity η, the characteristic amplitude of the nonhydrostatic changes in the moment of inertia δC, and the added moment of inertia due to the equatorial bulge (C − A). For the nominal values η = 3 × 1022 Pa s and δC/(C − A) = 0.003, the maximum TPW is 61° over 100 Myr and 8° over 10 Myr. The maximum TPW speed is only sensitive to η, δC, and (C − A), and is 2.4° Myr‐1 for the nominal values. TPW is shown to act as a low‐pass filter; rapid changes in moment of inertia produce smaller and delayed TPW. A consequence of this is that inertial interchange TPW does not have a different character than TPW. TPW can have an important contribution to plate motions over relatively long timescales but not over shorter timescales. Our simple approach allows us to assess whether multiple TPW events are possible but the major uncertainty continues to be the mantle viscosity structure.
Controls on density stratification in the early mantle
Authors: Davies Geoffrey F.
Published: May 2007

Previous numerical models of convection in the hot early mantle, incorporating simulated subducted oceanic crust and some viscosity stratification, developed thermal and compositional stratification, with cooler, strongly depleted mantle above hotter, slightly enriched mantle. The robustness of these results is explored through variation of some important parameters. The stratification is minor at present mantle temperatures but stronger at higher mantle temperatures because mantle viscosities are reduced. The results are not much affected by variations in plate velocity, nor by whether internal heat sources are directly associated with the mafic component, nor by 20% of heat entering from below. However, stratification was reduced somewhat at higher temperatures by increasing the number of tracers, indicating that the effect was moderately overestimated in a previous paper. The present results still indicate that oceanic crust would be no more than 6–8 km thick at high mantle temperatures, because of the strong depletion of the upper mantle. When the effect of a phase transformation in the transition zone is included, the stratification is moderately enhanced and crustal thicknesses of 3–5 km result at 1650°C. Oceanic crustal thickness is highly variable in space and time, with some plates having essentially zero crust for significant periods. The new results support the previous conclusions that the stratification may explain the strong depletion of incompatible elements documented for the earliest mantle and that early plate tectonics may have been more viable that hitherto thought.
Prochlorococcus contributes to new production in the Sargasso Sea deep chlorophyll maximum
Authors: Casey John R. , Lomas Michael W. , Mandecki Joanna , Walker Donald E.
Published: May 2007

Prochlorococcus is ubiquitous in tropical oceans, but its biogeochemical role is not well constrained. For example, cultured Prochlorococcus clones do not grow on NO3−, but these cultured clones may only represent 10–15% of the natural population variance resulting in a biased biogeochemical role. We report NO3−, NO2−, NH4+ and urea uptake rates for flow‐cytometrically sorted Sargasso Sea Prochlorococcus populations. Reduced nitrogen substrates accounted for most, 90–95%, of the measured nitrogen uptake, but these populations also directly assimilate a significant fraction of NO3−, 5–10%; a finding in stark contrast to conclusions drawn from culture studies. The observed population‐specific NO3− uptake rates compare favorably with both net Prochlorococcus population growth rates and diapycnal NO3− fluxes. We hypothesize that while reduced nitrogen supports overall high growth rates, balancing high grazing mortality, the net seasonal Prochlorococcus population growth is supported by NO3− assimilation and that Prochlorococcus contributes to new production in the oligotrophic ocean.
Remote‐sensing magnetospheric dynamics with riometers: Observation and theory
Authors: Liu W. W. , Liang J. , Spanswick E. , Donovan E. F.
Published: May 2007

The importance of monitoring particle injection into the inner magnetosphere from the plasma sheet is exceeded perhaps only by its difficulty. The recent progress in using ground‐based riometer data [e.g., Spanswick et al., 2007] to detect by proxy particle injection has raised much hope that this important aspect of substorms can be more consistently monitored. In this paper we develop a theoretical model for explaining the observed dispersionless injection events reported by Spanswick et al. The substorm event on 3 October 1998 is analyzed to give the empirical context for riometer responses during a typical substorm. Our simulation shows that riometer electrons produce a clean and strong signal that can be uniquely and easily related to magnetic field dipolarization that normally gives rise to injection.
Using global positioning system‐derived crustal velocities to estimate rates of absolute sea level change from North American tide gauge records
Authors: Snay Richard , Cline Michael , Dillinger William , Foote Richard , Hilla Stephen , Kass William , Ray Jim , Rohde Jim , Sella Giovanni , Soler Tomás
Published: May 2007

We identified 37 tide gauges; each located within 40 km of a geodetic station whose International Terrestrial Reference Frame of 2000 (ITRF2000) crustal velocity had been rigorously derived from continuous global positioning system (GPS) observations, spanning from 3 to 11 years. The tide gauges are located along the coasts of North America, Bermuda, Hawaii, and Kwajalein (in the Marshall Islands). We obtained the ITRF2000 crustal velocities by averaging values from six solutions; each produced by a team of investigators acting, essentially, independently of the other teams. We then applied crustal velocities to convert rates of relative sea level change to rates of absolute sea level change. In a sample containing 30 sites, we found that the mean rate of absolute sea level change equals 1.80 ± 0.18 mm/yr in the 1900–1999 period. The scatter about the mean for individual sites in this sample is characterized by a (weighted) RMS value of 0.85 mm/yr. This scatter primarily reflects the uncertainty associated with derived crustal velocities. The remaining seven sites, i.e., five sites on the Pacific coast of Alaska, one on Dauphin Island (Alabama), and one on Kwajalein (an atoll in the Pacific Ocean), experienced relatively low rates of absolute sea level change. We hypothesize the low rates in Alaska are caused by ongoing melting of mountain glaciers and ice masses near the stations, while the low rates found for Dauphin Island and Kwajalein remain unexplained.
A wind tunnel investigation of the deformation of water drops in the vertical and horizontal electric fields
Authors: Bhalwankar R. V. , Kamra A. K.
Published: May 2007

Deformation of the uncharged water drops freely suspended in a vertical wind tunnel and subjected to vertical, horizontal, or no external electric field is investigated using movie photography. Electric field elongates the drop along its direction, and the elongation increases with the increase in electric field. Horizontal electric fields are more efficient than vertical ones in deforming the drop. The larger the drop, the larger is the difference between the distortions in the vertical and horizontal field configurations. As compared to the case of no electric field, horizontal electric field, as low as 1 kV cm−1, changes the ratio of minor‐to‐major axis of the 2.6‐mm diameter drop by ∼3%. An examination of the frequency distribution of the drop’s axis ratio shows that during its oscillations, oblateness decreases more often when subjected to vertical electric field and increases more often when subjected to horizontal electric field. Extreme values of distortion increase and are attained more frequently when drop is oscillating in electric field. It is concluded that the drop size distribution will be wider and thus the rate of drop’s growth faster in those regions of cloud where the electric field direction is vertical rather than horizontal.
The impact of interannual variability on multidecadal total ozone simulations
Authors: Fleming Eric L. , Jackman Charles H. , Weisenstein Debra K. , Ko Malcolm K. W.
Published: May 2007

We have used a two‐dimensional chemistry and transport model to study the effects of interannual dynamical variability on global total ozone for 1979–2004. Long‐term meteorological data from the National Centers for Environmental Prediction‐National Center for Atmospheric Research (NCEP‐NCAR) reanalysis‐2 project and the European Center for Medium Range Weather Forecasts (ECMWF) updated reanalysis (ERA‐40) are used to construct yearly dynamical fields for use in the model. The simulations qualitatively resolve much of the seasonal and interannual variability observed in long‐term global total ozone data, including fluctuations related to the quasi‐biennial oscillation (QBO). We performed a series of model experiments to examine the relative roles of the interannual variability, changes in halogen and volcanic aerosol loading, and the 11‐year solar cycle in controlling the multidecadal ozone changes. Statistical regression is used to isolate these signals in the observed and simulated time series. At Northern midlatitudes, the simulated interannual dynamical variability acts to reinforce the chemical ozone depletion caused by the enhanced aerosol loading following the eruption of Mt. Pinatubo in 1991. However, at Southern midlatitudes, the interannual variability masks the aerosol‐induced chemical effect. The simulated solar cycle response in total ozone is generally consistent with observations and is primarily due to the direct photochemical effect. The halogen‐induced total ozone trend for 1979–1996 derived from the model is in good agreement with that derived from observations in the tropics and the Northern Hemisphere (NH). However, at Southern midlatitudes, the trend derived from the model is more sensitive to halogen loading than that derived from observations.
Size distributions of dicarboxylic acids and inorganic ions in atmospheric aerosols collected during polar sunrise in the Canadian high Arctic
Authors: Kawamura Kimitaka , Narukawa Masahiro , Li Shao‐Meng , Barrie Leonard A.
Published: May 2007

Size‐segregated atmospheric aerosols (11 stages separating particles from <0.04 to >14.2 μm) collected in the Arctic during the polar sunrise at Alert were analyzed for aerosol mass, dicarboxylic acids, and major inorganic ions. Oxalic, malonic, succinic, and glutaric acids were detected in all size ranges, with oxalic acid being dominant. Their concentrations maximized in the accumulation mode either at 0.24–0.40 or 0.40–0.8 μm aerodynamic diameters, suggesting that diacids were mainly formed by gas‐to‐particle conversion via photochemical oxidation of nonmethane hydrocarbons and oxygenated organics originated from continental pollution sources. The relative abundances of oxalic acid were higher in the 0.24‐ to 0.4‐μm size particles (73–78%) than in supermicrometer particles (40–60%), indicating that oxalic acid is produced by gas phase oxidation of precursors followed by accumulation on preexisting particles. Mass size distributions of NH4+ and SO42− peaked in the accumulation mode similar to those of small diacids. The sea‐salt enrichment factor of K+ (biomass burning tracer) relative to Na+ maximized in 0.1‐ to 0.8‐μm sizes, whereas those of Mg2+ and Ca2+ (dust tracers) in 0.4‐ to 7.8‐μm particles. Maximized chlorine loss and bromine enrichment were found at 0.4–0.8 and 0.24–0.4 μm sizes, respectively. Concentrations of Br−, which typically showed a submicrometer maximum, increased significantly during an O3 depletion event having a shift of size distribution to a supermicrometer mode. During this event, oxalic acid concentration relative to succinic acid increased in submicrometer mode (0.24–0.4 μm), adding to a growing body of evidence supporting the hypothesis that halogen chemistry is important in the production and loss of oxalic acid in the arctic atmosphere.
A magmatic loading model for coronae on Venus
Authors: Dombard Andrew J. , Johnson Catherine L. , Richards Mark A. , Solomon Sean C.
Published: May 2007

Models for the formation of coronae, quasi‐circular, volcanotectonic features on Venus, must explain four critical characteristics: coronae display (1) a wide range of diameters, (2) complex, varied topography, (3) fracture annuli, and (4) sometimes extensive volcanism. Previous models have difficulty simultaneously satisfying all four constraints. On the basis of observations and interpretations of features on Venus and Earth and experiments in geophysical fluid dynamics, we propose that coronae form in response to magmatic loading of the crust over zones of partial melting at the tops of thermally buoyant heads of transient mantle plumes that impinge on the base of the thermal lithosphere. By tying corona formation to a melt zone and not directly to an impinging upwelling, our conceptual model can account for the wide range in corona diameters. Lateral crustal flow, facilitated by magmatic heating, may lead to central depressions characteristic of many coronae. A thermomechanical, finite element simulation with a dissipating thermal anomaly leads to crustal thinning and predicts an elevation profile consistent with one of the more populous topographic classes of coronae. Deformation concentrated at the transition from thicker to thinner lithosphere above the thermal anomaly yields a narrow annulus of enhanced differential stress, consistent with formation of fracture annuli. Estimates of excess heat in an upwelling exceed the thermal energy in the melt that comprises the corona. Band‐pass‐filtered maps of the topography and gravity fields in the Beta‐Atla‐Themis region are consistent with upwellings now impinging on the lithosphere beneath seven coronae previously inferred to be active.
Venus atmospheric circulation: Known and unknown
Authors: Limaye Sanjay S.
Published: May 2007

After a pause of more than two decades, Venus' atmosphere is being explored again. Since April 2006, European Space Agency's Venus Express has been acquiring data, exploiting the near‐infrared windows that allow us to peer into the deep night‐side atmosphere. In June 2007, NASA's MESSENGER mission will fly past Venus on its way to Mercury, collecting useful data for a few weeks. Instruments and experiments on Venus Express are expected to provide a more comprehensive set of atmospheric observations over three and perhaps more Venus days. Venus Express observations are already providing clues about the processes that maintain the rapid circulation of Venus' atmosphere. The early observations show not only that the global circulation is organized into two hemispheric vortices centered over respective poles, but also that the vortex organization extends deep into the atmosphere. The limited Galileo NIMS near‐infrared observations in 1989 had revealed the deep circulation in the equatorial regions, but because of the spacecraft, flyby trajectory could not observe the high latitudes to elucidate the polar circulation and its organization. The long hiatus in systematic Venus observations has provided an opportunity to perform some new analysis of the previous Pioneer Venus observations. This paper presents a synopsis of the circulation measurements at high latitudes and an analysis of the solar thermal tides seen in the cloud motions and suggests some limitations of previous estimates of transport of angular momentum by eddies.