bluuebunny/crossref_metadata_2025 huggingface dataset:
Wide-field cone bipolar cells and the blue-ON pathway to color-coded ganglion cells in rabbit retina
Authors: FAMIGLIETTI EDWARD V.
Published: February 2008

Wide-field cone bipolar cells with sparse dendritic branching and proposed connectivity to blue cones were first identified in rabbit and cat. In rabbit, these were subdivided into type a (wa) and type b (wb), with axonal branching in sublamina a, and sublamina b, respectively, of the inner plexiform layer (IPL). Recent studies in rabbit support the earlier hypothesis of exclusive blue/short wavelength cone connectivity for both types. The homologues of wb cells (but not wa cells) have been identified in other mammals. The axonal branching of wa cone bipolar cells is shown to co-stratify with the dendrites of the “fiducial,” type a starburst amacrine cell, although a few branches extend into sublamina b. The axon terminal of wb cone bipolar cells is shown to be narrowly stratified in stratum 5α, deep to the dendrites of the type b starburst amacrine cell. Rabbit ganglion cells postsynaptic to wa cells are unknown, but may include class III.2a cells, similarly stratified in the IPL. The wb axon terminal is shown here to co-stratify with and to make close, likely synaptic, contacts with the dendrites of a recently described morphological subtype of class II ganglion cell in rabbit retina, IIb2. Recent morpho-physiological correlation indicates that class IIb2 cells correspond to the blue-ON-center-X or ON-brisk-sustained ganglion cells, defined physiologically in rabbit. In contrast, the wb cell in cat retina must innervate the physiologically identified blue-ON-center-sluggish-sustained ganglion cell. In monkey retina, the wb-like bipolar cells apparently innervate a small, partly bi-stratified ganglion cell. Mammals share a common pathway from short-wavelength-sensitive (S/blue) cone photoreceptors to ON-center ganglion cells in sublamina b of the IPL, in the form of wb or wb-like cone bipolar cells, but the type of ganglion cell innervated appears to be particular, and may serve different functional roles in different mammalian orders.
Distribution of bipolar input to midget and parasol ganglion cells in marmoset retina
Authors: ERIKÖZ BAHAR , JUSUF PATRICIA R. , PERCIVAL KUMIKO A. , GRÜNERT ULRIKE
Published: February 2008

Different types of retinal ganglion cell show differences in their response properties. Here we investigated the question of whether these differences are related to the distribution of the synaptic input to the dendritic tree. We measured the distribution and density of synaptic input to the dendrites of midget and parasol ganglion cells in the retina of a New World monkey, the marmoset,Callithrix jacchus. Ganglion cells were retrogradely labeled by dye injection into parvocellular or magnocellular regions of the lateral geniculate nucleus and subsequently photo-filled. Presumed bipolar cell synapses were identified immunocytochemically using antibodies against the ribbon protein CtBP2 or the GluR4 subunit of the AMPA receptor. For all cells, colocalized immunoreactive puncta were distributed across the entire dendritic tree. The density of the presumed bipolar input to midget ganglion cells was comparable for both synaptic markers, suggesting that the AMPA receptor GluR4 subunit is expressed at all synapses between midget bipolar and midget ganglion cells. Midget ganglion cells had an average of nine colocalized immunoreactive puncta per 100 μm2dendritic surface, and parasol cells had an average of seven colocalized immunoreactive puncta per 100 μm2dendritic surface. The densities were comparable in different regions of the dendritic tree and were not influenced by the location of the cells with respect to the fovea. Our findings suggest that the differences in the response characteristics of midget and parasol cells are not due to differences in the density of synaptic input to their dendritic tree.
Gender-specific modulation of short-term neuroplasticity in the visual cortex induced by transcranial direct current stimulation
Authors: CHAIEB LEILA , ANTAL ANDREA , PAULUS WALTER
Published: February 2008

Transcranial direct current stimulation (tDCS) is a non-invasive method of modulating levels of cortical excitability. In this study, data gathered over a number of previously conducted experiments before and after tDCS, has been re-analyzed to investigate correlations between sex differences with respect to neuroplastic effects. Visual evoked potentials (VEPs), phosphene thresholds (PTs), and contrast sensitivity measurements (CSs) are used as indicators of the excitability of the primary visual cortex. The data revealed that cathodally induced excitability effects 10 min post stimulation with tDCS, showed no significant difference between genders. However, stimulation in the anodal direction revealed sex-specific effects: in women, anodal stimulation heightened cortical excitability significantly when compared to the age-matched male subject group. There was no significant difference between male and female subjects immediately after stimulation. These results indicate that sex differences exist within the visual cortex of humans, and may be subject to the influences of modulatory neurotransmitters or gonadal hormones which mirror short-term neuroplastic effects.
Visual efference inLimulus: In vitrotemperature-dependent neuromodulation of photoreceptor potential timing by octopamine and substance P
Authors: LIM-KESSLER CORRINNE C.M. , BOLBECKER AMANDA R. , LI JIA , WASSERMAN GERALD S.
Published: February 2008

Efferents from the brain ofLimuluscourse toward its lateral eye and release octopamine and substance P into it. These neurotransmitters have previously been found to act as neuromodulators in this visual system by altering the size of its responses to light. We report here that both also modulate the timing of the receptor potentials (RPs) evoked by brief light flashes and that these timing effects are temperature dependent. Specifically: We extend our previous report that octopamine prolongs ambient RPs in a categorical fashion and here demonstrate that it does the same at colder temperatures. Categorical means that a given RP is either clearly prolonged in a dramatic fashion or its duration is otherwise unremarkable. Octopamine also accelerates the onsets of RPs when they are evoked by weak flashes under cold temperatures. Contrariwise, substance P accelerates RPs at all temperatures and this acceleration dramatically reduces the sluggishness that is otherwise typically present at low temperatures. Quantitative analysis of intensity-response functions also demonstrated that light sensitivity under substance P is significantly augmented. The plain temporal antagonism between these two modulators demonstrates that the visual system ofLimuluspossesses a well-poised mechanism which could be used to adjust the timing of its neural processing to interface well with the temporal characteristics of those visual stimuli that are currently present.
Osmotic properties ofLimulusseawaters and organ cultures: An unrecognized issue
Authors: LIM-KESSLER CORRINNE C.M. , BOLBECKER AMANDA R. , LI JIA , WASSERMAN GERALD S.
Published: February 2008

Excised eyes of the horseshoe crab (Limulus polyphemus) have long provided robust preparations for fundamental studies of the visual neuroscience of photoreceptors. Such preparations are particularly useful for immersion in perfusion chambers whose perfusate can be varied as needed. Little attention has been paid in the past to the osmotic properties of such perfusates because they have generally been virtually isotonic with natural seawater. We here report that (1) some recentLimulusstudies have used organ culture perfusates that are severely hypotonic and (2) that that fact has not been adequately disclosed.
Visual Neuroscience is turning twenty
Authors: Reese Benjamin
Published: February 2008

Your journal enters its third decade with the publication of this issue. The first volume, published in 1988, appeared in quarterly issues, but moved to bi-monthly production in 1989, and then monthly release from 1990 through 1992. Two volumes appeared each year during 1989–1992, accounting for the fact that this twenty-first year coincides with volume 25. In 1993, it returned to bi-monthly publication, remaining so for the past 15 years. During this period, other vision-related journals have made their debut, but Visual Neuroscience remains a premier venue for publishing fundamental research in the neurobiology of vision.
Beccaria's Luxury of Comfort and Happiness of the Greatest Number
Authors: CAMCASTLE CARA
Published: February 2008

Section I explores and articulates Beccaria's theory of luxury. Social classes tend to emulate the classes immediately above and below them. When a class increases the luxury that it consumes, this causes a chain reaction of increased demand for luxury by other classes. Satisfying the resulting new demand for luxury and non-luxury goods maximizes the happiness of a greater number of citizens. Following the consequentialist principle of utility theory, Beccaria concludes that luxury is beneficial. His writings are compared to those of Hume, Bentham and others. In section II Beccaria's demonstration that freedom of choice is a universally desired luxury indispensable for well-being in all human societies is contrasted to Rousseau's belief that luxury diminishes liberty and happiness. Beccaria values the distributive more than the aggregative maximization of utility in his analysis of luxury; the article explains why this carries wider implications for utilitarian theory.
Happiness, the Self and Human Flourishing
Authors: HAYBRON DANIEL M.
Published: February 2008

The psychological condition of happiness is normally considered a paradigm subjective good, and is closely associated with subjectivist accounts of well-being. This article argues that the value of happiness is best accounted for by a non-subjectivist approach to welfare: a eudaimonistic account that grounds well-being in the fulfillment of our natures, specifically in self-fulfillment. And self-fulfillment consists partly in authentic happiness. A major reason for this is that happiness, conceived in terms of emotional state, bears a special relationship to the self. These arguments also point to a more sentimentalist approach to well-being than one finds in most contemporary accounts, particularly among Aristotelian forms of eudaimonism.
Value, Reason and Hedonism
Authors: HILLS ALISON
Published: February 2008

It is widely believed that we always have reason to maximize the good. Utilitarianism and other consequentialist theories depend on this ‘teleological’ conception of value. Scanlon has argued that this view of value is not generally correct, but that it is most plausible with regard to the value of pleasure, and may even be true at least of that. But there are reasons to think that even the value of pleasure is not teleological.
Pettit's Non-iteration Constraint
Authors: MCALEER SEAN
Published: February 2008

I discuss Philip Pettit's argument thatappreciationis not a proper response to value because it fails to satisfy the non-iteration constraint, according to which, whereVis a value andRis a response to value,R-ingVmust not be distinct fromR-ingR-ingV.After motivating the non-iteration constraint and conceding that appreciation fails to satisfy the constraint, I argue that the consequentialist's preferred response to value,promotion, also violates the constraint, leaving Pettit with a dilemma: if he insists on the constraint, then promotion is not a proper response to value; if he does not insist on the constraint, then his argument against appreciation as a proper response to value fails.
Off Her Trolley? Frances Kamm and the Metaphysics of Morality
Authors: NORCROSS ALASTAIR
Published: February 2008

Frances Kamm's aptly titled Intricate Ethics is a tour de force of what Peter Unger calls the ‘preservationist’ approach to ethical theory. Here is some of what she says about her methodology:

Consider as many case-based judgments of yours as prove necessary. Do not ignore some case-based judgments, assuming they are errors, just because they conflict with simple or intuitively plausible principles that account for some subset of your case-based judgments. Work on the assumption that a different principle can account for all of the judgments. Be prepared to be surprised at what this principle is . . . . I say, consider your case-based judgments, rather than a survey of everyone's judgments. This is because I believe that much more is accomplished when one person considers her judgments and then tries to analyze and justify their grounds than if we do mere surveys. (5)
Discerning Subordination and Inviolability: A Comment on Kamm's Intricate Ethics
Authors: RICHARDSON HENRY S.
Published: February 2008

Frances Kamm has for some time now been a foremost champion of non-consequentialist ethics. One of her most powerful non-consequentialist themes has been the idea of inviolability. Morality's prohibitions, she argues, confer on persons the status of inviolability. This thought helps articulate a rationale for moral prohibitions that will resist the protean threat posed by the consequentialist argument that anyone should surely be willing to violate a constraint if doing so will minimize the overall number of such violations. As Kamm put it in a 1992 article, ‘If morality permitted minimizing violations of persons by violating other persons, then each of those saved as well as those persons used to save others would be less inviolable. It is the permission, not any actual violation of persons, that makes this so.’ Now, as thus baldly asserted, this claim borders on the conclusory. It is almost as if the claim were that morality conferred on persons the following status: that of being protected from consequentialism. One wants to hear in what inviolability consists, in more detail, so that we can understand it independently of the negation of consequentialism. And there is also an opposite problem: if inviolability is a good, then why can't consequentialism take it into account? Hence, one also wants to hear why this would not be the case.
Double Effect, Triple Effect and the Trolley Problem: Squaring the Circle in Looping Cases
Authors: OTSUKA MICHAEL
Published: February 2008

In the Trolley Case (Figure 1), as devised by Philippa Foot and modified by Judith Jarvis Thomson, a runaway trolley (i.e. tram) is headed down a main track and will hit and kill five unless you divert it onto a side track, where it will hit and kill one.
Responses to Commentators on Intricate Ethics
Authors: KAMM F. M.
Published: February 2008

Some of the commentators on Intricate Ethics (IE) complain of my method. One finds the main ideas ‘Kammouflaged’ because the relevant causal distinctions are so fine-grained and the cases that illustrate them so numerous (Richardson, p. 82). Some say that they do not have the intuitions about many cases that I have, that I concoct dubious and ad hoc distinctions and invest them with moral significance; I am Ptolemaic in that new crystalline spheres and epicycles are constantly being added in an attempt to fix the appearances (Norcross, p. 74).
Concurrent comparison of energy intake and expenditure among adults in Butajira District, Ethiopia
Authors: Tesfaye Fikru , Byass Peter , Wall Stig
Published: February 2008

Objective

To estimate and compare dietary energy intake (DEI) and total energy expenditure (TEE) among adults, using questionnaires.

Design

Comparative, cross-sectional study.

Setting

Community-based, at the demographic surveillance site (DSS) in Butajira District of Ethiopia.

Subjects

A total of 619 adults, 18–64 years of age, were randomly selected from among the urban and rural population of Butajira using the DSS sampling frame. Habitual dietary intake and physical activity were assessed using questionnaires. BMR was estimated using a regression equation, and TEE was calculated from BMR and the metabolic energy equivalent task (MET) and duration of reported activities. Physical activity level (PAL) was calculated as TEE/BMR, while food intake level (FIL) was calculated as DEI/BMR. The mean DEI:TEE ratio was used to evaluate reported DEI at the population level, while individual misreporters were identified by applying the Goldberg cut-off points at three levels of PAL.

Results

Based on the Goldberg method, 57 % of the study participants were identified as acceptable reporters of DEI, among whom mean TEE was 8·21 (95 % CI 8·01, 8·42) MJ (1963 (95 % CI 1914, 2012) kcal), mean DEI was 8·13 (95 % CI 7·93, 8·34) MJ (1944 (95 % CI 1895, 1993) kcal) and mean DEI:TEE was 1·01 (95 % CI 0·99, 1·04).

Conclusion

The dietary history and physical activity questionnaires provide comparable estimates of mean energy intake and expenditure at a population level. Acceptable reporters have to be identified in order to obtain better estimates. Questionnaire-based estimates of energy intake should not be interpreted without an inherent system of comparison or validation.
Leucine 7 to proline 7 polymorphism in the neuropeptide Y gene and changes in serum lipids during a family-based counselling intervention among school-aged children with a family history of CVD
Authors: Salminen Marika , Lehtimäki Terho , Fan Yue-Mei , Vahlberg Tero , Kivelä Sirkka-Liisa
Published: February 2008

Objective

To compare whether serum lipids and their changes during a health education intervention are associated with the Leu7Pro polymorphism in the signal peptide part of neuropeptide Y (NPY) in children with normal weight and in those with overweight.

Design

An intervention study.

Setting

A family-based intervention of risk factors for prevention of CHD in Finland.

Subjects

Subjects were 443 children with a family history of CVD participating in family-based health education. The children were divided into two groups according to NPY genotype: children with Leu7/Pro7 or Pro7/Pro7 genotype (n50) and children with Leu7/Leu7 genotype (n393). The final sample of the follow-up study included 353 (80 %) children (Pro7 allelle carriers,n43; Leu7/Leu7,n310).

Results

At baseline, the Leu7Pro polymorphism was not associated with serum lipid values after adjustment for body weight in boys or girls. There was a significant interaction of NPY genotype group by time and body weight (P= 0·043 for three-way interaction: time × NPY genotype × body weight) in LDL-cholesterol (LDL-C) concentration among boys. LDL-C decreased among boys with normal weight in both NPY groups and in overweight boys with the Leu7/Leu7 genotype, whereas it increased in overweight boys with the Pro7 allele. Two-way interaction (time × NPY genotype) showed no significant differences in changes of serum lipids between the NPY genotype groups among boys or girls.

Conclusions

The Leu7Pro polymorphism may be associated with dietary response to LDL-C concentration in overweight boys with a family history of early-onset CVD.
Perceived subject outcomes and impact on health-related quality of life associated with diet using the new Food Benefits Assessment (FBA©) questionnaire: development and psychometric validation
Authors: Guyonnet Denis , Chassany Olivier , Picard Céline , Guillemin Isabelle , Meunier Juliette , Seignobos Eva , Vigneux Marc , Lassel Taous , Trudeau Elyse
Published: February 2008

Objective

To assess the perceived outcomes associated with diet/food intake in the general adult population.

Design and subjects

The Food Benefits Assessment (FBA©) questionnaire was developed from subjects’ verbatim transcripts (n 18) and after comprehension tests (n 5). Normal-weight (n 130) and overweight (n 67) subjects then completed the final questionnaire twice, 7 d apart. Psychometric properties were assessed, including construct validity by principal components analysis (PCA), concurrent validity (Spearman coefficient) with the Short Form-36 scale (SF-36), known-group validity by comparing FBA dimension scores according to lifestyle and clinical variables, internal consistency reliability (Cronbach’s α) and test–retest reproducibility in stable subjects over 1 week (intraclass correlation coefficient, ICC).

Results

PCA and Multitrait analysis confirmed the final version of the FBA comprising forty-one items split into seven dimensions (vitality; digestive comfort; physical appearance; well-being; snacking; disease prevention; aesthetics). All dimensions displayed good item convergent validity (0·44 to 0·80), good concurrent validity (highest correlation between well-being dimension of FBA and mental health scale of SF-36, r = 0·83) and good known-group validity and reproducibility (ICC ≥ 0·76); internal consistency reliability was good to excellent (Cronbach’s α = 0·79 to 0·91).

Conclusion

The FBA is the first valid and reliable questionnaire that allows the assessment of diet effects and impact as perceived by subjects. It is a good candidate in the nutrition field for further use in specific population settings and with a particular food or daily diet. Linguistically validated English (UK and US) and German versions of the questionnaire are available.
How to achieve long-term breast-feeding: factors associated with early discontinuation
Authors: Camurdan Aysu Duyan , Ilhan Mustafa N , Beyazova Ufuk , Sahin Figen , Vatandas Nilgun , Eminoglu Sancar
Published: February 2008

Objectives

To evaluate the factors associated with discontinuation of breast-feeding before 12 months in order to make suggestions for achieving long-term breast-feeding.

Design

A descriptive cross-sectional study.

Setting

Gazi University Medical School, Ankara, Turkey.

Subjects

Mothers of 1230 children who discontinued breast-feeding at least 15 d before the last visit were asked to fill out a questionnaire about the discontinuation process. Logistic regression analysis was performed to assess the independent effects of factors that might influence breast-feeding discontinuation.

Results

Mean breast-feeding duration of the study group was 11·04 (sd 7·45) months. Introduction of bottle-feeding correlated with discontinuation of breast-feeding (r = 0·507, P = 0·001). Important risk factors for discontinuation of breast-feeding before the first 12 months were not exclusively breast-feeding at 3 and 6 months, prematurity, not having a plan about breast-feeding duration and maternity leave duration of ≤91 d for working mothers. The common reasons for abandoning breast-feeding in the first and second 6 months were similar, namely the mother’s concerns about the sufficiency of breast milk. After 12 months and 18 months the reasons for discontinuation were the baby’s unwillingness to eat solid foods while breast-feeding and the mother’s perception that ‘the baby is old enough’, respectively.

Conclusion

The factors that improve long-term breast-feeding are successful exclusive breast-feeding in the first few months, intention of the mother to breast-feed and sufficient duration of maternity leave. This study emphasizes the importance of successful breast-feeding counselling during the first few months to achieve the desired long-term breast-feeding.
BRAF kinase in melanoma development and progression
Authors: DeLuca Amena M. , Srinivas Archana , Alani Rhoda M.
Published: February 2008

Cutaneous melanoma is increasing in incidence at one of the highest rates for any form of cancer in the USA, with a current lifetime incidence of 1 in 68. Although early-stage disease is often curable, the survival rate for advanced disease is low, with an average life expectancy of 6–10 months. Knowledge of the molecular alterations associated with melanoma development and progression is expected to lead to improved therapies and outcomes. Major progress in defining the molecular alterations associated with the evolution of melanoma came in 2002, through a systematic genome-wide assessment of cancer-associated pathways. Large-scale sequencing of growth-associated genes in a variety of cancers identified a high frequency (>60%) of activating mutations of the BRAF kinase gene in human melanomas. This discovery has prompted a large number of studies evaluating the biological significance of BRAF kinase mutations in the initiation and progression of melanoma, and their importance for the development of novel melanoma therapies. Here we review the most recent studies of BRAF kinase in the pathogenesis of melanoma and their implications for defining BRAF kinase as a therapeutic point of interest in melanoma.
Intercomparison of homogenization techniques for precipitation data
Authors: Beaulieu Claudie , Seidou Ousmane , Ouarda Taha B. M. J. , Zhang Xuebin , Boulet Gilles , Yagouti Abderrahmane
Published: February 2008

This paper presents an intercomparison of eight statistical tests to detect inhomogeneities in climatic data. The objective was to select those that are more suitable for precipitation data in the southern and central regions of the province of Quebec, Canada. The performances of these methods were evaluated by simulation on several thousands of homogeneous and inhomogeneous synthetic series. These series were generated to reproduce the statistical characteristics of typical precipitations observed in the southern and central parts of the province of Quebec and nearby areas, Canada. It was found that none of these methods was efficient for all types of inhomogeneities, but some of them performed substantially better than others: the bivariate test, the Jaruskova's method, and the standard normal homogeneity test. Techniques such as the Student sequential test and the two‐phase regression led to the worst performances. The analysis of the performances of each method in several situations allowed the design of an optimal procedure that takes advantage of the strengths of the best performing techniques.
Reconciling temperatures of metamorphism, fluid fluxes, and heat transport in the upper crust at intermediate to fast spreading mid‐ocean ridges
Authors: Coogan Laurence A.
Published: February 2008

Current models of the mineralogical and chemical modification of the crust within mid‐ocean ridge hydrothermal systems at intermediate to fast spreading ridges are difficult to reconcile with the temperature distribution predicted by the required fluid fluxes. In particular, the sharp increase in metamorphic grade passing down from the lavas into the sheeted dike complex places important constraints on the flow of fluid through the crust. This distribution of metamorphic temperatures has typically been discussed in terms of a step in permeability in the downwelling limb of a single‐pass convection cell. Simple modeling of this system shows that downwelling fluid cools the crust too efficiently for high‐temperature metamorphism of the upper dikes to occur in the downflow zone. In fact, temperatures throughout most of the sheeted dike complex are too high. Three alternative models are considered. Fluid‐rock reaction during the cooling of each dike from magmatic temperatures is difficult to reconcile with cooling rate estimates for dikes, reaction rates required to grow metamorphic minerals, and the relatively constant composition of many hydrothermal vents. Metamorphism during reheating of the crust after fluid flow slows or stops is difficult to reconcile with the required fluid fluxes during metamorphism, based on the Sr‐isotopic composition of the sheeted dike complex, and cannot produce high enough temperatures in the upper dikes and low temperatures in the lower lavas. In contrast, fluid‐rock reaction in the sheeted dike complex as hot fluids migrate upward after being heated by the underlying magma source appears to be consistent with the data. In this model, downwelling seawater cools the recharge zone, and the fluid only becomes hot enough to significantly alter the crust once it approaches the conductive boundary layer overlying the magma chamber. Metamorphism of the sheeted dike complex then largely occurs in the discharge zone.
Fast time response measurements of gaseous nitrous acid using a tunable diode laser absorption spectrometer: HONO emission source from vehicle exhausts
Authors: Li Yongquan Q. , Schwab James J. , Demerjian Kenneth L.
Published: February 2008

We present the measurement of gaseous nitrous acid (HONO) using a tunable diode laser absorption spectrometer. This method utilizes one strong absorption feature at 1713.511cm−1, which is free of interference and suitable for ambient HONO measurements. The detection limit for a 1‐second integration time is determined to be better than 200 pptv. The measurement method has been demonstrated by sampling room air over an 11‐day period. HONO mixing ratios ranged from below the detection limit (≤200 pptv) to 4.8 ppbv, with a mean value of 0.73 ppbv. A number of elevated HONO events lasting from several seconds up to hours were observed and have been associated with roadway traffic adjacent to the building where the measurements were performed. The variation in the ratio of HONO/NOx and its anti‐correlation with ambient NOx measurements indicate that the source of HONO in this measurement study is mainly from the direct emission of traffic exhausts and local heterogeneous reactions. The demonstrated application of TDLAS fast response measurement technology is capable of providing new information on the sources and sinks of HONO in the environment.
Europe‐Mediterranean tomography: High correlation between new seismic data and independent geophysical observables
Authors: Fry B. , Boschi L. , Ekström G. , Giardini D.
Published: February 2008

To improve the fidelity of European tomographic images, we implement variable resolution parameterization, finite‐frequency and ray theory, and improved data coverage in new tomographic inversions. We supplement an existing high‐quality database of global teleseismic phase velocity observations of both Love and Rayleigh waves with a set of new phase delay observations recorded by a dense array of stations in the region. We invert these data to find global phase velocity maps, characterized by a more densely parameterized Europe and Mediterranean. We compare our seismic images with laterally variable independent geophysical observables, including crustal thickness, gravity, and heat flow and find correlations between 0.25 and 0.6. While at most periods finite‐frequency and ray‐theory yield almost coincident results, we find some possibly significant differences in the phase velocity of 150s Rayleigh waves. Our results represent significant progress toward high‐resolution modeling of upper mantle S‐velocity structure, with the possibility of also constraining seismic anisotropy.
Mapping the low salinity Changjiang Diluted Water using satellite‐retrieved colored dissolved organic matter (CDOM) in the East China Sea during high river flow season
Authors: Sasaki Hiroaki , Siswanto Eko , Nishiuchi Kou , Tanaka Katsuhisa , Hasegawa Toru , Ishizaka Joji
Published: February 2008

Absorption coefficients of colored dissolved organic matter (CDOM) [ag(λ)] were measured and relationship with salinity was derived in the East China Sea (ECS) during summer when amount of the Changjiang River discharge is large. Low salinity Changjiang Diluted Water (CDW) was observed widely in the shelf region and was considered to be the main origin of CDOM, resulting in a strong relationship between salinity and ag(λ). Error of satellite ag(λ) estimated by the present ocean color algorithm could be corrected by satellite‐retrieved chlorophyll data. Satellite‐retrieved salinity could be predicted with about ±1.0 accuracy from satellite ag(λ) and the relation between salinity and ag(λ). Our study suggests that satellite‐derived ag(λ) can be an indicator of the low salinity CDW during summer.
The role of tidal forcing in the Gulf of Alaska's circulation
Authors: Auad Guillermo , Miller Arthur J.
Published: February 2008

High resolution (7 km) numerical simulations of the Gulf of Alaska circulation show an indirect effect induced by tidal forcing. Tides stir the water column more vigorously in the coastal ocean than in the Gulf's interior, leading to denser waters there than offshore. This horizontal gradient induces a geostrophic current that, in general and in most regions, flows against the mean general circulation.
Three‐dimensional radar observation of a submillimeter meteoroid fragmentation
Authors: Kero J. , Szasz C. , Pellinen‐Wannberg A. , Wannberg G. , Westman A. , Meisel D. D.
Published: February 2008

We present and discuss two examples of pulsating meteor events observed with the tristatic 930 MHz EISCAT UHF radar system. One of them provides the first strong observational evidence of a submillimeter‐sized meteoroid breaking apart into two distinct fragments. The received power fluctuates regularly in the time profiles of all three receivers, but the fluctuation frequencies are different. The pulsations are interpreted as being due to interference from two distinct scattering centers and the three detected pulsation rates are utilized to calculate the differential velocity of the fragments. The result is consistent with interference from two fragments of unequal cross‐sectional area over mass ratio, separating from each other due to different deceleration along the trajectory of their parent meteoroid. The other meteor event is an example of a meteoroid undergoing quasi‐continuous disintegration. This manifests itself as simultaneous pulsations at all three receivers. Both observations indicate a head echo target upper size limit of the order of half the 32 cm radar wavelength.
Aerosol radiative forcing and climate sensitivity deduced from the Last Glacial Maximum to Holocene transition
Authors: Chylek Petr , Lohmann Ulrike
Published: February 2008

We use the temperature, carbon dioxide, methane, and dust concentration record from the Vostok ice core to deduce the aerosol radiative forcing during the Last Glacial Maximum (LGM) to Holocene transition and the climate sensitivity. A novel feature of our analysis is the use of a cooling period between about 42 KYBP (thousand years before present) and LGM to provide a constraint on the aerosol radiative forcing. We find the change in aerosol radiative forcing during the LGM to Holocene transition to be 3.3 ± 0.8 W/m2 and the climate sensitivity between 0.36 and 0.68 K/Wm−2 with a mean value of 0.49 ± 0.07 K/Wm−2. This suggests a 95% likelihood of warming between 1.3 and 2.3 K due to doubling of atmospheric concentration of CO2. The ECHAM5 model simulation suggests that the aerosol optical depth during the LGM may have been almost twice the current value (increase from 0.17 to 0.32).
Use of SF5CF3 for ocean tracer release experiments
Authors: Ho David T. , Ledwell James R. , Smethie William M.
Published: February 2008

SF6 tracer release experiments (TREs) have provided fundamental insights in many areas of Oceanography. Recently, SF6 has emerged as a powerful transient tracer, generating a need for an alternative tracer for large‐scale ocean TREs. SF5CF3 has the potential to replace SF6 in TREs, due to similarities in their properties and behavior, as well as techniques for injection, sampling, and analysis. The suitability of SF5CF3 for TREs was examined in Santa Monica Basin, off the coast of Southern California. In January 2005, a mixture of ca. 10 mol of both SF6 and SF5CF3 was injected on an isopycnal surface near 800 m depth. Over the next 23 months, concentrations of the two tracers mirrored each other very closely, indicating that SF5CF3 is a viable replacement for SF6 in ocean TREs. The mixing parameters inferred from the experiment confirmed the results from an earlier SF6 TRE in the Santa Monica Basin.
Computer simulations on the initiation and morphological difference of Japan winter and summer sprites
Authors: Asano Tomokazu , Hayakawa Masashi , Cho Mengu , Suzuki Tomoyuki
Published: February 2008

Two‐dimensional (axisymmetric) computer simulations (electromagnetic code) have been performed to study the initiation and morphological difference (summer, carrots, and winter, columns) of sprites for simulating Japan summer and winter sprites. By changing the physical parameters of a parent lightning, we have found the following findings by looking at the spatial‐temporal distribution of reduced electric field, etc. (1) There are three important factors (the height where the charge is removed (ds), charge transfer (Q), and lightning current risetime (τ)) in the initiation of sprites and their morphological differences. (2) For the initiation of sprites, the charge transfer (Q) should exceed a certain value for possible charge heights (giving us a threshold of charge moment change (Qds) of the order of ∼120–200 C·km), with a combination of small risetime of lightning current waveform. (3) Further, the height for positive charge is much higher than that for negative charge in a typical lightning configuration, which is the essential factor in determining the morphological difference of sprites in summer and winter. Positive charges for summer are located at a much higher altitude than those in winter in Japan, which might result in carrot‐type in summer and columnar‐type in winter even for the same positive polarity. (4) A combinational effect of (Ids) and (Qds) is important for having sprites. Finally, the present computer results on the initiation of sprites for Japanese lightning have been compared extensively to the well‐documented properties of summer continental sprites and future subjects to study have been suggested.
Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems
Authors: Waite Gregory P. , Chouet Bernard A. , Dawson Phillip B.
Published: February 2008

The current eruption at Mount St. Helens is characterized by dome building and shallow, repetitive, long‐period (LP) earthquakes. Waveform cross‐correlation reveals remarkable similarity for a majority of the earthquakes over periods of several weeks. Stacked spectra of these events display multiple peaks between 0.5 and 2 Hz that are common to most stations. Lower‐amplitude very‐long‐period (VLP) events commonly accompany the LP events. We model the source mechanisms of LP and VLP events in the 0.5–4 s and 8–40 s bands, respectively, using data recorded in July 2005 with a 19‐station temporary broadband network. The source mechanism of the LP events includes: 1) a volumetric component modeled as resonance of a gently NNW‐dipping, steam‐filled crack located directly beneath the actively extruding part of the new dome and within 100 m of the crater floor and 2) a vertical single force attributed to movement of the overlying dome. The VLP source, which also includes volumetric and single‐force components, is 250 m deeper and NNW of the LP source, at the SW edge of the 1980s lava dome. The volumetric component points to the compression and expansion of a shallow, magma‐filled sill, which is subparallel to the hydrothermal crack imaged at the LP source, coupled with a smaller component of expansion and compression of a dike. The single‐force components are due to mass advection in the magma conduit. The location, geometry and timing of the sources suggest the VLP and LP events are caused by perturbations of a common crack system.
Effects of wind trend and gustiness on the sea drag: Lake George study
Authors: Babanin Alexander V. , Makin Vladimir K.
Published: February 2008

The air‐sea coupling is usually parameterized in terms of the drag coefficient Cd, but the scatter of experimental data around such dependences is very significant and has not improved noticeably over some 30 years. In the paper, which is meant to be the first in a series, a complex approach to the problem is suggested. Multiple mechanisms, contributing into the sea drag, are to be singled out, studied separately, evaluated and then reunited in a joint parameterization for Cd. Dependences of the drag coefficient on the wind speed and sea state, and effects of wind trends and gustiness are investigated in detail. Gustiness is found to be responsible for the most distant outliers. Our approach also combines an experimental Lake George study with theoretical investigations conducted by means of the WOWC (Wind‐Over‐Waves Coupling) model. Overall agreement of the model with measured wind stresses is quite good, within 20% for the bulk of the data. Lower envelopes of the drag dependences are an important result of the paper. They provide some Lake George “ideal” relationships for the sea drag. Almost any deviation from such conditions causes the drag to increase. It is suggested that decrease of the drag with respect to the ideal conditions, which exhibits itself in a number of known open ocean data sets, would be caused by a momentum flux back from the waves to the wind due to long waves outrunning the wind. Behavior of the Charnock parameter in terms of wave age is also considered.
West Antarctic Peninsula sea ice in 2005: Extreme ice compaction and ice edge retreat due to strong anomaly with respect to climate
Authors: Massom Robert A. , Stammerjohn Sharon E. , Lefebvre Wouter , Harangozo Stephen A. , Adams Neil , Scambos Theodore A. , Pook Michael J. , Fowler Charles
Published: February 2008

In September–October 2005, the juxtaposition of low‐ and high‐pressure anomalies at 130°W and 60°W, respectively, created strong and persistent northerly airflow across the West Antarctic Peninsula (WAP). This had a major impact on regional sea ice conditions, with extreme ice compaction in the Bellingshausen and East Amundsen seas (60°W−130°W) but divergence in the West Amundsen and East Ross seas. This resulted in the former in a highly compact marginal ice zone and ice cover, mean modeled ice thicknesses of >5 m, and an earlier‐than‐average maximum extent (mid‐August). While rapid ice retreat in late winter‐spring created a major negative ice extent anomaly, compact ice persisted in the subsequent summer. Other effects were anomalies in air temperature (of +1°C to +5°C) and precipitation rates (to >2.5 mm/d). The patterns in late 2005 are consistent with the occurrence of a weak La Niña and a near‐neutral Southern Annular Mode, with a quasi‐stationary zonal wave three pattern dominating hemispheric atmospheric circulation. Once a compact ice edge was created, it took only one additional week of strong winds to “solidify” the pack in place. Conditions in 2005 are analyzed in the context of 1979−2005 and compared with the springs of 1993, 1997, 1999, 2001, and 2004. A statistically significant increase of the northerly 10‐m wind component between 110°W and 125°W occurred in the Septembers of 1979−2005. No clear trends occur in other spring months. This work underlines the key importance of ice dynamics in recent changes in the WAP sea ice régime.
Thin sea ice thickness as inferred from passive microwave and in situ observations
Authors: Naoki Kazuhiro , Ukita Jinro , Nishio Fumihiko , Nakayama Masashige , Comiso Josefino C. , Gasiewski Al
Published: February 2008

Microwave radiometric signals from sea ice strongly reflect physical conditions of a layer near the ice surface. This study examines the extent to which the relationships of thickness with brightness temperature and with emissivity hold for thin sea ice, approximately <0.2–0.3 m, and how those relationships may arise from changes in brine characteristics through modification of dielectric properties near the ice surface. In order to address these questions we made concurrent measurements of sea ice thickness in the Sea of Okhotsk from a ship and passive microwave radiometry from an over‐flying aircraft. The results show that the brightness temperature and emissivity increase with thickness approximately within the thin ice for a frequency range of 10–37 GHz. The relationship is more pronounced at lower frequencies and at the horizontal polarization. We also established an empirical relationship between ice thickness and salinity in the layer near the ice surface from a field experiment, which qualitatively supports the idea that changes in the near‐surface brine characteristics contribute to the observed thickness‐brightness temperature/emissivity relationship. On the basis of our results, we conclude that for thin ice, passive microwave radiometric signals likely contain indirect information on ice thickness through the dependence of dielectric properties on brine, which provides a plausible and common explanation for previously proposed passive microwave thickness algorithms.
ICESat measurements of sea ice freeboard and estimates of sea ice thickness in the Weddell Sea
Authors: Zwally H. Jay , Yi Donghui , Kwok Ron , Zhao Yunhe
Published: February 2008

Sea ice freeboard heights in the Weddell Sea of Antarctica are derived from the Ice, Cloud, and Land Elevation Satellite (ICESat) laser altimeter measurements, which have a unique range precision to flat surfaces of 2 cm within 70 m footprints spaced at 172 m along track. Although elevations of flat surfaces can be obtained to an accuracy of ∼10 cm (1σ) per footprint, direct determination of freeboard heights is precluded by errors in knowledge of the geoid and temporal variability of the ocean surface. Therefore freeboards are determined relative to an ocean reference level detected over areas of open water and very thin ice within the sea ice pack using an along‐track filtering method. The open water/thin ice selections show good agreement in the combined analysis of ICESat segments and Envisat Synthetic Aperture Radar (SAR) imagery. The average residual between the ICESat‐measured ocean level and the EGM96 geoid is 1.4 m. Estimates of snow depth on the sea ice from AMSR‐E passive microwave data along with nominal densities of snow, water, and sea ice are used to estimate sea ice thickness. Four periods of ICESat data in May–June (fall) and October–November (late winter) of 2004 and 2005 between longitudes 298°E and 360°E are analyzed. In the fall the mean freeboards are 0.28 m in 2004 and 0.29 m in 2005, and the mean thicknesses are 1.33 m in 2004 and 1.52 m in 2005. In late winter the freeboards grew to 0.37 m in 2004 and 0.35 in 2005, and the thicknesses grew to 2.23 m in 2004 and 2.31 m in 2005. The interannual differences in freeboard are small, and the larger interannual change in estimated thickness mainly represents differences in the snow depth estimates. Seasonal changes in the spatial patterns of freeboard and thickness over the 4 months correlate with the expected circulation of sea ice in the Weddell Sea, as indicated by sea ice velocity fields.
The quasi 5‐day signal in the mesospheric water vapor concentration at high latitudes in 2003‐a comparison between observations at ALOMAR and calculations
Authors: Sonnemann G. R. , Hartogh P. , Grygalashvyly M. , Li Song , Berger U.
Published: February 2008

A quasi 5‐day signature in different middle atmospheric parameters such as the horizontal wind, the temperature, the pressure, the occurrence rate of Polar Mesospheric Summer Echoes (PMSEs) and Noctilucent Clouds (NLCs) or the ozone concentration has been found during the last decades since the 1970s. These effects were interpreted in terms of the impact of a 5‐day planetary normal mode (1,1) of Rossby waves. In the mesosphere the quasi 5‐day variation is predominantly a summer phenomenon occurring in high and middle latitudes. Water vapor measurements were carried out by means of the microwave technique in high latitudes at ALOMAR (69.29°N, 16.03°E), Norway, for the year 2003. The observations revealed a clear signature of a quasi 5‐day variation. Using our real‐date Leibniz‐Institute Middle Atmosphere (LIMA) model of the Institute of Atmospheric Physics in Kühlungsborn, Germany, in a case study for the same period we found a very clear quasi 5‐day signal in the distribution of the minor constituents and particularly in the water vapor mixing ratio in middle to high northern latitudes in the late spring and summer season. A similar finding is valid for the southern hemisphere half a year later. The variations of the minor constituents are triggered by the wind system resulting from the dynamical part of the model. The calculations satisfactorily reproduce the observed water vapor concentrations. In particular, the annual variation including intraannual variations is reflected by the model. We discuss the findings in terms of dynamics and chemistry.