bluuebunny/crossref_metadata_2025 huggingface dataset:
Semliki forest virus core protein fragmentation: Its possible role in nucleocapsid disassembly
Authors: Schlegel Andreas , Schaller Johann , Jentsch Pia , Kempf Christoph
Published: February 2005

Semliki Forest virus (SFV) envelope proteins function as proton pores under mildly acidic conditions and translocate protons across the viral membrane [Schlegel, A., Omar, A., Jentsch, P., Morell, A. and Kemp, F. C. (1991) Biosci. Rep. 11, 243–255]. As a consequence, during uptake of SFV by cells via receptor-mediated endocytosis the nucleocapsid is supposed to be exposed to protons. In this paper the effects of mildly acidic pH on SFV nucleocapsids were examined. A partial proteolytic fragmentation of core proteins was observed when nucleocapsids were exposed to mildly acidic pH. A similar proteolytic event was detected when intact SFV virions were exposed to identical conditions. Protease protection assays with exogenous bromelain provided evidence that the capsid protein degradation was due to an endogenous proteolytic activity and not to a proteolytic contamination. Detergent solubilization of virus particles containing degraded nucleocapsids followed by sucrose gradient centrifugation led to a separation of capsid protein fragments and remaining nucleocapsids. These data are discussed in terms of a putative biological significance, namely that the core protein fragmentation may play a role in nucleocapsid disassembly.
Functional specification and proof of correctness for time dependent behaviour of reactive systems
Authors: Alagar Vangalur S. , Ramanathan Geetha
Published: February 2005

A functional formalism for describing and reasoning about the time dependent behaviour of reactive systems is presented. The model is event based and can describe the histories of events with finite duration. It is a generalisation of the model of Caspi and Halbwachs (1986). A set of tools with their operations are introduced in the formalism and structure theorems characterising the algebra of events are proved. The power of this extended model is illustrated through the formal specification and correctness proof for a problem chosen from robotics.
Multiple Primary Carcinomas with Esophageal Squamous Cell Cancer: Clinicopathologic Outcome
Authors: Natsugoe Shoji , Matsumoto Masataka , Okumura Hiroshi , Ishigami Sumiya , Uenosono Yoshikazu , Owaki Tetsuhiro , Takao Sonshin , Aikou Takashi
Published: February 2005

The incidence of multiple primary carcinomas (MPCs) associated with esophageal cancer has increased. The purpose of this study was to analyze clinicopathologic findings for MPC and for only esophageal cancer (OEC). Of 157 patients with MPCs, 60 had synchronous cancer and 97 metachronous cancer. Another 42 patients had antecedent esophageal cancer (AEC), and 55 patients had subsequent esophageal cancer (SEC). We retrospectively analyzed the clincopathologic findings for patients in these categories. The incidence of early‐stage carcinoma was higher in patients with MPCs than in those with an OEC. Of patients with MPCs, those with metachronous cancer had a higher rate of early‐stage carcinoma than those with synchronous cancer. The 5‐year survival rates were not significantly different for MPC and OEC patients. Patients with metachronous cancer had a significantly better prognosis than those with synchronous cancer (p = 0.017); and in the metachronous cancer group the prognosis was significantly better for patients with AEC than for those with SEC (p = 0.0005). Meticulous follow‐up after treatment of a first cancer should be required to detect other early‐stage carcinomas.
Hepatic Surgery Using the Ligasure Vessel Sealing System
Authors: Romano Fabrizio , Franciosi Claudio , Caprotti Roberto , Uggeri Fabio , Uggeri Franco
Published: February 2005

Blood loss, a well‐known risk factor for morbidity and mortality during liver resection, occurs during parenchymal transection, so many approaches and devices have been developed to limit bleeding. Surgical technique is an important factor in preventing intraoperative and postoperative complications. The aim of the present study was to determine whether the bipolar vessel sealing device allows a safe and careful liver transection, achieving a satisfactory hemostasis thus reducing blood loss and related complications.

A total of 30 consecutive patients (18 male, 12 female with a mean age of 63 years) underwent major and minor hepatic resection in which the bipolar vessel sealing device was used without routine inflow occlusion. A crush technique followed by energy application was used to perform the parenchymal transection. No other devices were applied to achieve hemostasis. The bipolar vessel sealing device was effective in 27 cases of hepatic resection. It failed to achieve hemostasis in three patients, all of whom had a cirrhotic liver. Median blood loss was 250 ml (range: 100‐1600 ml), and intraoperative blood transfusions were required in five patients (17%). Mean operative time was 200 minutes (range: 140‐360 minutes). There was no clinical evidence of postoperative hemorrhage, bile leak, or intraabdorninal abscess.

The postoperative complication rate was 17%. The bipolar vessel sealing device is a useful tool in standard liver resection in patients with a normal liver parenchyma, but its use should be avoided in cirrhotic livers.
Experimental Evaluation of Bursting Pressure in Lymphatic Vessels with Ultrasonically Activated Shears
Authors: Abe Kaoru , Terashima Masanori , Fujiwara Hisataka , Takagane Akinori , Uesugi Noriyuki , Saito Kazuyoshi
Published: February 2005

To evaluate the ability of ultrasonically activated shears (USAS) to occlude lymphatic vessels, we investigated the bursting pressure of lymphatic vessels occluded with USAS and compared with pressures in an artery and a vein. The inguinal lymphatic vessels, testicular arteries, and testicular veins were removed from male pigs. The vessels were occluded by USAS at power level 2. The bursting pressures of the harvested vessels were measured ex vivo. The bursting pressure of the artery (average, 1154 mmHg; range, 1000‐1341 mmHg) was significantly greater than that in the vein (average, 747 mmHg; range, 560‐973 mmHg; p = 0.0024) or the lymphatic vessel (average, 610 mmHg; range, 491‐996 mmHg; p = 0.0003). There was no significant difference of bursting pressure between the vein and lymphatic vessel (p = 0.2226). Although the bursting pressures of the vein and lymphatic vessel were significantly lower than that of the artery, they were much higher than that found in physiologic conditions. USAS is considered to be a powerful tool for lymph node dissection for malignant diseases in open surgery as well as laparoscopic surgery.
Strategies of space occupation by anchovy and sardine in the southern Benguela: the role of stock size and intra-species competition
Authors: Barange Manuel , Coetzee Janet C. , Twatwa Nandipha M.
Published: February 2005

Strategies of space occupation by anchovy and sardine populations in the southern Benguela during cruises in 1994 (low biomass) and 2001 (high biomass) are investigated using geostatistical tools. The spatial expansion of anchovy and sardine during the high-density year resulted in an increase in the number and density of hotspots and, in the case of anchovy, a relative increase in the contribution of mid- to high-density intervals to the overall survey biomass. Variogram autocorrelation ranges were larger in the high-biomass year. Otherwise, similarities and differences in the strategies of space occupation between anchovy and sardine are consistent between years of low and high biomass, and are therefore density-independent. Variograms of indicator variables revealed comparable structures for both species and years, with autocorrelation ranges of 30 nautical miles for the smallest indicator (0.1 g m−2) and 10 miles for the largest (100 g m−2), reflecting intrinsic spatial structures independent of stock size. The ideal survey inter-transect distance, defined as the autocorrelation range of the highest density indicator, was not influenced by the expanded distribution of both species. Cumulative frequency distributions and cross-variograms revealed differences in space occupancy between both species. Despite the areal expansion, and in contrast to anchovy, a significant portion of the sardine biomass continued to be contributed by a few very high-density areas with little spatial structure, as indicated by large nugget effects in the variograms and lack of transitions in the cross-variograms. Both species were spatially segregated in the low-biomass year, but overlapped extensively in the high-biomass year.
Medieval Warming, Little Ice Age, and European impact on the environment during the last millennium in the lower Hudson Valley, New York, USA
Authors: Pederson Dee Cabaniss , Peteet Dorothy M. , Kurdyla Dorothy , Guilderson Tom
Published: February 2005

Establishing natural climate variability becomes particularly important in large urban areas in anticipation of droughts. We present a well-dated bi-decadal record of vegetation, climate, land use, and fire frequency from a tidal marsh in the Hudson River Estuary. The classic Medieval Warm Period is evident through striking increases in charcoal and Pinus dominance from ∼800–1300 A.D., paralleling paleorecords southward along the Atlantic seaboard. Higher inputs of inorganic sediment during this interval suggest increased watershed erosion during drought conditions. The presence of the Little Ice Age ensues with increases in Picea and Tsuga, coupled with increasing organic percentages due to cooler, moister conditions. European impact is manifested by a decline in arboreal pollen due to land clearance, increased weedy plant cover (i.e., Ambrosia, Plantago, and Rumex), and an increase in inorganic particles to the watershed.
The construct of internalization: conceptualization, measurement, and prediction of smoking treatment outcome
Authors: SCOTT ACTON G. , KUNZ JEFFREY D. , WILSON MARK , HALL SHARON M.
Published: February 2005

Background. Depression symptoms and diagnoses are associated with failure to quit smoking in most studies, but not all.

Method. A new measure of internalization (i.e. symptoms of depression or anxiety, or poor mood) was created to investigate whether internalization would predict smoking cessation in 549 smokers from three randomized clinical trials with inconsistent findings.

Results. Predicted item locations based on a map of the construct of internalization agreed with empirical locations based on item response theory. Internalization was highly correlated with neuroticism. Logistic regressions showed that internalization improved upon the predictions of other affect-related measures. High baseline internalization decreased abstinence from smoking at end of treatment and 3 months thereafter. History of major depression (single-episode or recurrent) failed to predict abstinence.

Conclusions. The broad, dimensional construct of internalization as conceptualized herein appears to be an important predictor of smoking cessation.
Latent class typology of nicotine withdrawal: genetic contributions and association with failed smoking cessation and psychiatric disorders
Authors: XIAN HONG , SCHERRER JEFFREY F. , MADDEN PAMELA A. F. , LYONS MICHAEL J. , TSUANG MING , TRUE WILLIAM R. , EISEN SETH A.
Published: February 2005

Background. Nicotine withdrawal is associated with failed smoking cessation and thus contributes to continuance of the habit and increases risk of smoking-related illnesses. Withdrawal is also associated with psychiatric disorders such as depression and alcoholism. However, relatively little is known about how to characterize the severity of withdrawal, including whether withdrawal subtypes exist in male smokers. If so, do these subtypes represent quantitative or qualitative differences?

Method. Smoking and withdrawal data were obtained from 4112 male–male twin pairs of the Vietnam Era Twin Registry during a 1992 administration of the Diagnostic Interview Schedule. Latent Class Analysis (LCA) was used to derive significantly different nicotine withdrawal profiles, and their association with psychiatric disorders was assessed. Genetic and environmental contributions and the correlation between these contributions were evaluated using bivariate biometrical modeling of the withdrawal phenotype and failed smoking cessation.

Results. The LCA model which best fit the data was a four-class severity continuum. Psychiatric disorders were significantly associated with more severe classes and the magnitude of the association increased as withdrawal severity increased. Genetics accounted for 31% and 51% of the variance in risk for withdrawal and failed cessation, respectively. The genetic contributions were significantly correlated (r=0·37).

Conclusions. Nicotine withdrawal classes are characterized by quantitative differences. The strong association between psychiatric disorders and withdrawal severity and the significant genetic correlation between withdrawal and cessation highlight the importance of withdrawal severity. Further refinement of the DSM definition of withdrawal to incorporate severity ratings may be warranted.
The severely mentally ill in residential facilities: a national survey in Italy
Authors: de GIROLAMO GIOVANNI , PICARDI ANGELO , SANTONE GIOVANNI , FALLOON IAN , MOROSINI PIERLUIGI , FIORITTI ANGELO , MICCIOLO ROCCO
Published: February 2005

Objective. In Italy, Residential Facilities (RFs) have completely replaced Mental Hospitals (MHs) for the residential care of mentally ill patients. We studied all patients resident in 265 randomly sampled Italian RFs (20% of the total).

Method. Structured interviews focusing on each patient were conducted by trained research assistants with the manager and staff of each RF. Patients were rated with the HoNOS and the GAF, and comprehensive information about their sociodemographic and clinical status and care history were gathered.

Results. Of the 2962 patients living in the sampled facilities, most were males (63·2%) who had never married, more than 70% were over 40 years; 85% on a pension, most commonly because of psychiatric disability. A substantial proportion (39·8%) had never worked and very few were currently employed (2·5%); 45% of the sample was totally inactive, not even assisting with domestic activities in the facility. Two-thirds had a diagnosis of schizophrenia; co-morbid or primary substance abuse were uncommon. Twenty-one per cent had a history of severe interpersonal violence, but violent episodes in the RFs were infrequent. The managers judged almost three-quarters appropriately placed in their facilities and considered that very few had short-term prospects of discharge.

Conclusions. Italian RFs cater for a large patient population of severely mentally ill requiring residential care. Discharge to independent accommodation is uncommon. Future studies should attempt to clarify how to match residential programmes with patients' disabilities.
Lifetime risk and persistence of psychiatric disorders across ethnic groups in the United States
Authors: BRESLAU JOSHUA , KENDLER KENNETH S. , SU MAXWELL , GAXIOLA-AGUILAR SERGIO , KESSLER RONALD C.
Published: February 2005

Background. Recent research in the United States has demonstrated striking health disparities across ethnic groups. Despite a longstanding interest in ethnic disadvantage in psychiatric epidemiology, patterns of psychiatric morbidity across ethnic groups have never been examined in a nationally representative sample.

Method. Ethnic differences in psychiatric morbidity are analyzed using data from the National Comorbidity Survey (NCS). The three largest ethnic groups in the United States – Hispanics, Non-Hispanic Blacks and Non-Hispanic Whites – were compared with respect to lifetime risk and persistence of three categories of psychiatric disorder: mood disorder, anxiety disorder, and substance use disorder.

Results. Where differences across ethnic groups were found in lifetime risk, socially disadvantaged groups had lower risk. Relative to Non-Hispanic Whites, Hispanics had lower lifetime risk of substance use disorder and Non-Hispanic Blacks had lower lifetime risk of mood, anxiety and substance use disorders. Where differences were found in persistence of disorders, disadvantaged groups had higher risk. Hispanics with mood disorders were more likely to be persistently ill as were Non-Hispanic Blacks with respect to both mood disorders and anxiety disorders. Closer examination found these differences to be generally consistent across population subgroups.

Conclusions. Members of disadvantaged ethnic groups in the United States do not have an increased risk for psychiatric disorders. Members of these groups, however, do tend to have more persistent disorders. Future research should focus on explanations for these findings, including the possibility that these comparisons are biased, and on potential means of reducing the disparity in persistence of disorders across ethnic groups.
The stability of the Parental Bonding Instrument over a 20-year period
Authors: WILHELM KAY , NIVEN HEATHER , PARKER GORDON , HADZI-PAVLOVIC DUSAN
Published: February 2005

Background. The Parental Bonding Instrument (PBI) measures the perception of being parented to the age of 16 years. Low scores on the care dimension and high scores on the overprotection dimension are considered to be risk factors of depression. While the PBI has been shown to be a reliable and valid instrument, the stability of the PBI over extended periods (taking into account individual characteristics and life experience) needs to be demonstrated.

Method. The PBI was measured in a non-clinical cohort on four waves between 1978 and 1998, along with a series of self-report measures including state depression and neuroticism. Differences in PBI change over time were examined by gender, lifetime major depression diagnosis, and life event variables, as well as by scores on neuroticism and state depression.

Results. Acceptable retest coefficients on PBI scores over the 20-year study were found for the cohort. No differences were found in PBI scores over time on the variables examined, including sex and depression measures.

Conclusions. The results indicate long-term stability of the PBI over time. The influences of mood state and life experience appear to have little effect on the stability of the perception of parenting as measured by the PBI. The present study increases confidence in the PBI as a valid measure of perceived parenting over extended time periods.
Stability of functional impairment in patients with schizotypal, borderline, avoidant, or obsessive–compulsive personality disorder over two years
Authors: SKODOL ANDREW E. , PAGANO MARIA E. , BENDER DONNA S. , TRACIE SHEA M. , GUNDERSON JOHN G. , YEN SHIRLEY , STOUT ROBERT L. , MOREY LESLIE C. , SANISLOW CHARLES A. , GRILO CARLOS M. , ZANARINI MARY C. , McGLASHAN THOMAS H.
Published: February 2005

Background. A defining feature of personality disorder (PD) is an enduring pattern of inner experience and behavior that is stable over time. Follow-up and follow-along studies have shown considerable diagnostic instability of PDs, however, even over short intervals. What, then, about personality disorder is stable? The purpose of this study was to determine the stability of impairment in psychosocial functioning in patients with four different PDs, in contrast to patients with major depressive disorder (MDD) and no PD, prospectively over a 2-year period.

Method. Six hundred treatment-seeking or treated patients were recruited primarily from clinical services in four metropolitan areas of the Northeastern USA. Patients were assigned to one of five diagnostic groups: schizotypal (STPD) (n=81), borderline (BPD) (n=155), avoidant (AVPD) (n=137), or obsessive–compulsive (OCPD) (n=142) personality disorders or MDD and no PD (n=85), based on the results of semi-structured interview assessments and self-report measures. Impairment in psychosocial functioning was measured using the Longitudinal Interval Follow-up Evaluation (LIFE) at baseline and at three follow-up assessments.

Results. Significant improvement in psychosocial functioning occurred in only three of seven domains of functioning and was largely the result of improvements in the MDD and no PD group. Patients with BPD or OCPD showed no improvement in functioning overall, but patients with BPD who experienced change in personality psychopathology showed some improvement in functioning. Impairment in social relationships appeared most stable in patients with PDs.

Conclusion. Impairment in functioning, especially social functioning, may be an enduring component of personality disorder.
Synaptic organization of GABAergic amacrine cells in the salamander
retina
Authors: ZHANG JUN , WANG HO-HWA , YANG CHEN-YU
Published: February 2005

The synaptic organization of GABA-immunoreactive (GABA-IR) amacrine
cells in the inner plexiform layer (IPL) of salamander retina was
studied with the use of postembedding immuno-electron microscopy. A
total of 457 GABA-IR amacrine synapses, with identified postsynaptic
elements, were analyzed on photomontages of electron micrographs
covering 3,618 μm2 of the IPL. GABA-IR amacrine synapses
were distributed throughout the IPL, with a small peak at the proximal
margin of sublamina a. The majority of the output targets
(81%) were GABA(−) neurons. Most of the contacts were simple
synapses with one postsynaptic element identified as a process of an
amacrine cell (55%), bipolar cell (19%) or ganglion cell (26%), and
serial synapses were very rare. Of the 89 postsynaptic bipolar
terminals, 63% participated in a reciprocal feedback synapse with the
same presynaptic GABA-IR amacrine profile. There appeared to be no
preference between GABA-IR amacrine contacts with rod- or
cone-dominated bipolar cells (9.1% vs. 8.9%) or in the total
number of amacrine synapses in sublaminas a and b
(52% vs. 47%). The preponderance of amacrine cell input to
bipolar cells in the OFF layer was derived from GABA-IR cells. These
findings provide ultrastructural support to the existing physiological
studies regarding the functional roles of the GABAergic amacrine cells
in this species. Our results have added to the data base demonstrating
that, in contrast to mammals, GABA-IR amacrine cells in amphibians and
other nonmammals contact other amacrine cells more frequently,
suggesting greater involvement of GABAergic amacrine cells in
modulating lateral inhibitory pathways.
Photopigment optical density of the human foveola and a paradoxical senescent increase outside the fovea
Authors: RENNER AGNES B. , KNAU HOLGER , NEITZ MAUREEN , NEITZ JAY , WERNER JOHN S.
Published: February 2005

Photopigment optical density (OD) of middle-(M) and long-(L) wavelength-sensitive cones was determined to evaluate the hypothesis that reductions in the amount of photopigment are responsible for age-dependent sensitivity losses of the human cone pathways. Flicker thresholds were measured at the peak and tail of the photoreceptor's absorption spectrum as a function of the intensity of a bleaching background. Photopigment OD was measured at 0 (fovea), 2, 4, and 8 deg in the temporal retina by use of a 0.3-deg-diameter test spot. Seventy-two genetically characterized dichromats were studied so that the L- and M-cones could be analyzed separately. Subjects included 28 protanopes with M- but no L-cones and 44 deuteranopes with L- but no M-cones (all male, age range 12–29 and 55–83 years). Previous methods have not provided estimates of photopigment OD for separate cone classes in the foveola. In this study, it was found that foveolar cones are remarkably efficient, absorbing 78% of the available photons (OD = 0.65). Photopigment OD decreased exponentially with retinal eccentricity independently of age and cone type. Paradoxically, the OD of perifoveal cones increased significantly with age. Over the 70-year age range of our participants, the perifoveal M- and L-cones showed a 14% increase in capacity to absorb photons despite a 30% decrease in visual sensitivity over the same period.
Voltage-clamp analysis and computational model of dopaminergic
neurons from mouse retina
Authors: XIAO JIANGUO , CAI YIDAO , YEN JASPER , STEFFEN MICHAEL , BAXTER DOUGLAS A. , FEIGENSPAN ANDREAS , MARSHAK DAVID
Published: February 2005

Isolated dopaminergic amacrine (DA) cells in mouse retina fire
rhythmic, spontaneous action potentials and respond to depolarizing
current with trains of low-frequency action potentials. To investigate
the roles of voltage-gated ion channels in these processes, the
transient A-type K+ current (IK,A) and
Ca2+ current (ICa) in isolated mouse DA cells
were analyzed by voltage clamp. The IK,A activated at
−60 mV and inactivated rapidly. ICa activated at
around −30 mV and reached a peak at 10 mV without apparent
inactivation. We also extended our previous computational model of the
mouse DA cell to include the new electrophysiological data. The model
consisted of a membrane capacitance in parallel with eight currents:
Na+ transient (INa,T), Na+ persistent
(INa,P), delayed rectifier potassium (IKdr),
IK,A, calcium-dependent potassium (IK,Ca), L-type
Ca2+ ICa, hyperpolarization-activated cation
current (Ih), and a leak current (IL).
Hodgkin-Huxley type equations were used to define the voltage- and
time-dependent activation and inactivation. The simulations were
implemented using the neurosimulator SNNAP. The model DA cell was
spontaneously active from a wide range of initial membrane potentials.
The spontaneous action potentials reached 35 mV at the peak and
hyperpolarized to −76 mV between spikes. The spontaneous firing
frequency in the model was 6 Hz. The model DA cell responded to
prolonged depolarizing current injection by increasing its spiking
frequency and eventually reaching a depolarization block at membrane
potentials greater than −10 mV. The most important current for
determining the firing rate was IK,A. When the amplitude of
IK,A was decreased, the firing rate increased.
ICa and IK,Ca also affected the width of action
potentials but had only minor effects on the firing rate. Ih
affected the firing rate slightly but did not change the waveform of
the action potentials.
MLA-sensitive cholinergic receptors involved in the detection of
complex moving stimuli in retina
Authors: REED B.T. , KEYSER K.T. , AMTHOR F.R.
Published: February 2005

Acetylcholine, acting through nicotinic acetylcholine receptors,
mediates the response properties of many ganglion cells in the rabbit
retina, including those that are directionally selective (DS; Ariel
& Daw, 1982a,b). For example, Grzywacz et al. (1998) showed that cholinergic input is necessary
for DS responses to drifting gratings, a form of textured stimulus.
However, the identities and locations of the neuronal acetylcholine
receptor (nAChR) subtypes that mediate this input are not clear (Keyser et al., 2000). We investigated the role of
methyllycaconitine-sensitive, α7-like nAChRs in mediating DS
responses to textured stimuli and apparent motion. We recorded
extracellularly from On–Off DS ganglion cells in rabbit retina
using everted eyecup preparations. Our data provide evidence that
MLA-sensitive nAChRs are involved in mediating directionally selective
responses to apparent motion and to a variety of complex, textured
stimuli such as drifting square-wave gratings, transparent motion, and
second-order motion.
Probing inner retinal circuits in the rod pathway: A comparison ofc-fosactivation in mutant mice
Authors: HANZLICEK BRETT W. , PEACHEY NEAL S. , GRIMM CHRISTIAN , HAGSTROM STEPHANIE A. , BALL SHERRY L.
Published: February 2005

We have used wild-type mice and mice possessing defects in specific retinal circuits in order to more clearly define functional circuits of the inner retina. The retina of thenobmouse lacks communication between photoreceptors and depolarizing bipolar cells (DBCs). Thus, all light driven activity in thenobmouse is mediatedviaremaining hyperpolarizing bipolar cell (HBC) circuits. Transducin null (Trα−/−) mice lack rod photoreceptor activity and thus remaining retinal circuits are solely generatedviacone photoreceptor activity. Activation in inner retinal circuits in each of these mice was identified by monitoring light-induced expression of an immediate early gene,c-fos. The number of cells expressingc-fosin the inner retina was dependent upon stimulus intensity and was altered in a systematic fashion in mice with known retinal mutations. To determine whetherc-fosis activatedviacircuits other than photoreceptors in the outer retina, we examinedc-fosexpression intulp1−/−mice that lack photoreceptors in the outer retina; these mice showed virtually noc-fosactivity following light exposure. Double-labeling immunohistochemical studies were carried out to more clearly define the population ofc-fosexpressing amacrine cells. Our results indicate thatc-fosmay be used to map functional circuits in the retina.
Effects of light intensity and pattern contrast on the ability of the land crab,Cardisoma guanhumi, to separate optic flow-field components
Authors: JOHNSON AARON P. , BARNES W. JON. P. , MACAULEY MARTIN W.S.
Published: February 2005

Using a novel suite of computer-generated visual stimuli that mimicked components of optic flow, the visual responses of the tropical land crab,Cardisoma guanhumi, were investigated. We show that crabs are normally successful in distinguishing the rotational and translational components of the optic flow field, showing strong optokinetic responses to the former but not the latter. This ability was not dependant on the orientation of the crab, occurring both in “forwards-walking” and “sideways-walking” configurations. However, under conditions of low overall light intensity and/or low object/background contrast, the separation mechanism shows partial failure causing the crab to generate compensatory eye movements to translation, particularly in response to low-frequency (low-velocity) stimuli. Using this discovery, we then tested the ability of crabs to separate rotational and translational components in a combined rotation/translation flow field under different conditions. We demonstrate that, while crabs can successfully separate such a combined flow field under normal circumstances, showing compensatory eye movements only to the rotational component, they are unable to make this separation under conditions of low overall light intensity and low object/background contrast. Here, the responses to both flow-field components show summation when they are in phase, but, surprisingly, there is little reduction in the amplitude of responses to rotation when the translational component is in antiphase. Our results demonstrate that the crab's visual system finds separation of flow-field components a harder task than detection of movement, since the former shows partial failure at light intensities and/or object/background contrasts at which movement of the world around the crab is still generating high-gain optokinetic responses.
Postsynaptic calcium feedback between rods and rod bipolar cells in the mouse retina
Authors: BERNTSON AMY , SMITH ROBERT G. , TAYLOR W. ROWLAND
Published: February 2005

Light-evoked currents were recorded from rod bipolar cells in a dark-adapted mouse retinal slice preparation. Low-intensity light steps evoked a sustained inward current. Saturating light steps evoked an inward current with an initial peak that inactivated, with a time constant of about 60–70 ms, to a steady plateau level that was maintained for the duration of the step. The inactivation was strongest at hyperpolarized potentials, and absent at positive potentials. Inactivation was mediated by an increase in the intracellular calcium concentration, as it was abolished in cells dialyzed with 10 mM BAPTA, but was present in cells dialyzed with 1 mM EGTA. Moreover, responses to brief flashes of light were broader in the presence of intracellular BAPTA indicating that the calcium feedback actively shapes the time course of the light responses. Recovery from inactivation observed for paired-pulse stimuli occurred with a time constant of about 375 ms. Calcium feedback could act to increase the dynamic range of the bipolar cells, and to reduce variability in the amplitude and duration of the single-photon signal. This may be important for nonlinear processing at downstream sites of convergence from rod bipolar cells to AII amacrine cells. A model in which intracellular calcium rapidly binds to the light-gated channel and reduces the conductance can account for the results.
A dynamic global vegetation model for studies of the coupled atmosphere‐biosphere system
Authors: Krinner G. , Viovy Nicolas , de Noblet‐Ducoudré Nathalie , Ogée Jérôme , Polcher Jan , Friedlingstein Pierre , Ciais Philippe , Sitch Stephen , Prentice I. Colin
Published: February 2005

This work presents a new dynamic global vegetation model designed as an extension of an existing surface‐vegetation‐atmosphere transfer scheme which is included in a coupled ocean‐atmosphere general circulation model. The new dynamic global vegetation model simulates the principal processes of the continental biosphere influencing the global carbon cycle (photosynthesis, autotrophic and heterotrophic respiration of plants and in soils, fire, etc.) as well as latent, sensible, and kinetic energy exchanges at the surface of soils and plants. As a dynamic vegetation model, it explicitly represents competitive processes such as light competition, sapling establishment, etc. It can thus be used in simulations for the study of feedbacks between transient climate and vegetation cover changes, but it can also be used with a prescribed vegetation distribution. The whole seasonal phenological cycle is prognostically calculated without any prescribed dates or use of satellite data. The model is coupled to the IPSL‐CM4 coupled atmosphere‐ocean‐vegetation model. Carbon and surface energy fluxes from the coupled hydrology‐vegetation model compare well with observations at FluxNet sites. Simulated vegetation distribution and leaf density in a global simulation are evaluated against observations, and carbon stocks and fluxes are compared to available estimates, with satisfying results.
Internal solitary waves in the Coastal Mixing and Optics 1996 experiment: Multimodal structure and resuspension
Authors: Bogucki D. J. , Redekopp L. G. , Barth J.
Published: February 2005

Observations of internal solitary waves (ISWs) and of their role in sediment resuspension during the Coastal Mixing and Optics 1996 (CMO 96) experiment are reported. The largest resuspension events observed in the experiment can be related to retarded flow under the wave footprint. Two distinctly different periods of resuspension events could be distinguished based on the prevailing atmospheric conditions: a calm period, which we consider characteristic of nominal conditions, and an energetic period, during which two major storms occurred. ISWs arrived at the mooring site from a variety of sources, though a common intermodal dynamics seemed to occur repeatedly. Both mode 1 and mode 2 ISWs have been observed. The present analysis of the month‐long portion of the CMO 96 data set constitutes the first reported observations, insofar as we are aware, of mode 2 waves on the continental shelf. Both mode 1 and mode 2 ISWs were found to stimulate resuspension. The mode 2 waves seem to be generated locally by resonant or topographic interactions with mode 1 ISWs. Internal wave fields of the type described here are expected to exist in a variety of other shallow seas as well.
Resolving mass flux at high spatial and temporal resolution using GRACE intersatellite measurements
Authors: Rowlands D. D. , Luthcke S. B. , Klosko S. M. , Lemoine F. G. R. , Chinn D. S. , McCarthy J. J. , Cox C. M. , Anderson O. B.
Published: February 2005

The GRACE mission is designed to monitor mass flux on the Earth's surface at one month and high spatial resolution through the estimation of monthly gravity fields. Although this approach has been largely successful, information at submonthly time scales can be lost or even aliased through the estimation of static monthly parameters. Through an analysis of the GRACE data residuals, we show that the fundamental temporal and spatial resolution of the GRACE data is 10 days and 400 km. We present an approach similar in concept to altimetric methods that recovers submonthly mass flux at a high spatial resolution. Using 4° × 4° blocks at 10‐day intervals, we estimate the mass of surplus or deficit water over a 52° × 60° grid centered on the Amazon basin for July 2003. We demonstrate that the recovered signals are coherent and correlate well with the expected hydrological signal.
A revised model of Jupiter's inner electron belts: Updating the Divine radiation model
Authors: Garrett Henry B. , Levin Steven M. , Bolton Scott J. , Evans Robin W. , Bhattacharya Bidushi
Published: February 2005

In 1983, Divine presented a comprehensive model of the Jovian charged particle environment that has long served as a reference for missions to Jupiter. However, in situ observations by Galileo and synchrotron observations from Earth indicate the need to update the model in the inner radiation zone. Specifically, a review of the model for 1 MeV < E < 100 MeV trapped electrons suggests that, based on the new synchrotron observations, the pitch angle distributions within L < 4 need to be updated by introducing two additional components: one near the Jovian magnetic equator and one at high magnetic latitudes. We report modifications to the model that reproduce these observations. The new model improves the fit to synchrotron emission observations and remains consistent with the original fit to the in situ Pioneer and Voyager data. Further modifications incorporating observations from the Galileo and Cassini spacecraft will be reported in the future.
Interferometric synthetic aperture radar study of Okmok volcano, Alaska, 1992–2003: Magma supply dynamics and postemplacement lava flow deformation
Authors: Lu Zhong , Masterlark Timothy , Dzurisin Daniel
Published: February 2005

Okmok volcano, located in the central Aleutian arc, Alaska, is a dominantly basaltic complex topped with a 10‐km‐wide caldera that formed circa 2.05 ka. Okmok erupted several times during the 20th century, most recently in 1997; eruptions in 1945, 1958, and 1997 produced lava flows within the caldera. We used 80 interferometric synthetic aperture radar (InSAR) images (interferograms) to study transient deformation of the volcano before, during, and after the 1997 eruption. Point source models suggest that a magma reservoir at a depth of 3.2 km below sea level, located beneath the center of the caldera and about 5 km northeast of the 1997 vent, is responsible for observed volcano‐wide deformation. The preeruption uplift rate decreased from about 10 cm yr−1 during 1992–1993 to 2 ∼ 3 cm yr−1 during 1993–1995 and then to about −1 ∼ −2 cm yr−1 during 1995–1996. The posteruption inflation rate generally decreased with time during 1997–2001, but increased significantly during 2001–2003. By the summer of 2003, 30 ∼ 60% of the magma volume lost from the reservoir in the 1997 eruption had been replenished. Interferograms for periods before the 1997 eruption indicate consistent subsidence of the surface of the 1958 lava flows, most likely due to thermal contraction. Interferograms for periods after the eruption suggest at least four distinct deformation processes: (1) volcano‐wide inflation due to replenishment of the shallow magma reservoir, (2) subsidence of the 1997 lava flows, most likely due to thermal contraction, (3) deformation of the 1958 lava flows due to loading by the 1997 flows, and (4) continuing subsidence of 1958 lava flows buried beneath 1997 flows. Our results provide insights into the postemplacement behavior of lava flows and have cautionary implications for the interpretation of inflation patterns at active volcanoes.
Wave‐current bedform scales, orientation, and migration on Sable Island Bank
Authors: Smyth C. E. , Li M. Z.
Published: February 2005

Field observations of wave‐current bedforms on Sable Island Bank show that medium to large bedforms were generally aligned with the wave direction, and did not follow the rotating tidal current. Normalized bedform heights and wavelengths were larger than predictions by Nielsen (1992), but agreed well with predictions by Khelifa and Ouellet (2000) which includes current effects. Maximum observed bedform wavelengths of 1.9 m were larger than those predicted for bedforms in wave‐dominated nearshore conditions, but this may be expected as the water depths are larger (20–42 m) and currents are present. Measured bedform migration rates had higher vector correlation amplitudes when compared to significant wave velocity than with current velocity or skewness. Migration rate predictions from three presently available models were not able to predict net migration rate and direction in all cases.
Time series analysis of regional climate model performance
Authors: Evans Jason P. , Oglesby Robert J. , Lapenta William M.
Published: February 2005

Four regional climate models (RegCM2, MM5/BATS, MM5/SHEELS, and MM5/OSU) were intercompared on a fairly small domain covering a relatively homogenous area in Kansas, United States, including the First International Satellite Land Surface Climatology Project (SLSCP) Field Experiment (FIFE) site. The models were integrated for a 2‐year period covering 1987 and 1988. The model results are evaluated against data collected during this time period at the Konza Prairie Long‐Term Ecological Research (LTER) site as well as over the summer observation periods of FIFE. The models all captured the proper qualitative behavior of the interannual variability, though the magnitudes varied considerably between models. They also found it particularly difficult to reproduce observed changes in the variance of surface variables. No model performed consistently better, with each model displaying particular strengths and weaknesses of its own. RegCM2 could be improved by including an ice phase in the cloud microphysics parameterization. MM5/BATS and MM5/SHEELS need revision of the formulation of stability dependence of the surface drag coefficients, including the coupling to the wind field, as well as using a total soil depth more representative of the area. MM5/OSU simulates too much resistance to evapotranspiration and fails to close the energy budget. All of the models overestimate runoff and evapotranspiration during winter, creating a dry anomaly which persists throughout the following summer. Development and verification of parameterizations involved in coupling the land surface and atmospheric components of these models together is at least as important as the development and verification of each component individually.
Interactions between mass balance, atmospheric circulation, and recent climate change on the Djankuat Glacier, Caucasus Mountains, Russia
Authors: Shahgedanova Maria , Stokes Chris R. , Gurney Stephen D. , Popovnin Viktor
Published: February 2005

This paper reports recent changes in the mass balance record from the Djankuat Glacier, central greater Caucasus, Russia, and investigates possible relationships between the components of mass balance, local climate, and distant atmospheric forcing. The results clearly show that a strong warming signal has emerged in the central greater Caucasus, particularly since the 1993/1994 mass balance year, and this has led to a significant increase in the summer ablation of Djankuat. At the same time, there has been no compensating consistent increase in winter precipitation and accumulation leading to the strong net loss of mass and increase in glacier runoff. Interannual variability in ablation and accumulation is partly associated with certain major patterns of Northern Hemisphere climatic variability. The positive phase of the North Pacific (NP) teleconnection pattern forces negative geopotential height and temperature anomalies over the Caucasus in summer and results in reduced summer melt, such as in the early 1990s, when positive NP extremes resulted in a temporary decline in ablation rates. The positive phase of the NP is related to El Niño‐Southern Oscillation, and it is possible that a teleconnection between the tropical Pacific sea surface temperatures and summer air temperatures in the Caucasus is bridged through the NP pattern. More recently, the NP pattern was predominantly negative, and this distant moderating forcing on summer ablation in the Caucasus was absent. Statistically significant correlations are observed between accumulation and the Scandinavian (SCA) teleconnection pattern. The frequent occurrence of the positive SCA phase at the beginning of accumulation season results in lower than average snowfall and reduced accumulation. The relationship between the North Atlantic Oscillation (NAO), Arctic Oscillation, and accumulation is weak, although positive precipitation anomalies in the winter months are associated with the negative phase of the NAO. A stronger positive correlation is observed between accumulation on Djankuat and geopotential height over the Bay of Biscay unrelated to the established modes of the Northern Hemisphere climatic variability. These results imply that the mass balance of Djankuat is sensitive to the natural variability in the climate system. Distant forcing, however, explains only 16% of the variance in the ablation record and cannot fully explain the recent increase in ablation and negative mass balance.
An analytical solution for transient radial flow through unsaturated fractured porous media
Authors: Wu Yu‐Shu , Pan Lehua
Published: February 2005

This paper presents analytical solutions for one‐dimensional radial transient flow through a horizontal, unsaturated fractured rock formation. In these solutions, unsaturated flow through fractured media is described by a linearized Richards' equation, while fracture‐matrix interaction is handled using the dual‐continuum concept. Although linearizing Richards' equation requires a specially correlated relationship between relative permeability and capillary pressure functions for both fractures and matrix, these specially formed relative permeability and capillary pressure functions are still physically meaningful. These analytical solutions can thus be used to describe the transient behavior of unsaturated flow in fractured media under the described model conditions. They can also be useful in verifying numerical simulation results, which as demonstrated in this paper, are otherwise difficult to validate.