bluuebunny/crossref_metadata_2025 huggingface dataset:
Wide variety of locations for rodent MATE1, a transporter protein that mediates the final excretion step for toxic organic cations
Authors: Hiasa Miki , Matsumoto Takuya , Komatsu Toshinori , Moriyama Yoshinori
Published: April 2006

MATE1 was the first mammalian example of the multidrug and toxin extrusion (MATE) protein family to be identified. Human MATE1 (hMATE1) is predominantly expressed and localized to the luminal membranes of the urinary tubules and bile canaliculi and mediates H+-coupled electroneutral excretion of toxic organic cations (OCs) into urine and bile (Otsuka M, Matsumoto T, Morimoto R, Arioka S, Omote H, and Moriyama Y. Proc Natl Acad Sci USA 102: 17923–17928, 2005). mMATE1, a mouse MATE ortholog, is also predominantly expressed in kidney and liver, although its transport properties are not yet characterized. In the present study, we investigated the transport properties and localization of mMATE1. Upon expression of this protein in HEK-293 cells, mMATE1 mediated electroneutral H+/tetraethylammonium exchange and showed a substrate specificity similar to that of hMATE1. Immunological techniques with specific antibodies against mMATE1 combined with RT-PCR revealed that mMATE1 is also expressed in various cells, including brain glia-like cells and capillaries, pancreatic duct cells, urinary bladder epithelium, adrenal gland cortex, α cells of the islets of Langerhans, Leydig cells, and vitamin A-storing Ito cells. These results indicate that mMATE1 is a polyspecific H+/OC exchanger. The unexpectedly wide distribution of mMATE1 suggests involvement of this transporter protein in diverse biological functions other than excretion of OCs from the body.
Enhanced excitability and suppression of A-type K+ current of pancreas-specific afferent neurons in a rat model of chronic pancreatitis
Authors: Xu Guang-Yin , Winston John H. , Shenoy Mohan , Yin Huaizhi , Pasricha Pankaj Jay
Published: April 2006

Chronic pancreatitis (CP) is a relatively common disorder, characterized by glandular insufficiency and chronic, often intractable, pain. The mechanism of pain in CP is poorly understood. We have previously developed a model of trinitrobenzene sulphonic acid (TNBS)-induced CP that results in nociceptive sensitization in rats. This study was designed to examine changes in the excitability and alteration of voltage-gated K+ currents of dorsal root ganglia (DRG) neurons innervating the pancreas. CP was induced in adult rats by an intraductal injection of TNBS. DRG neurons innervating the pancreas were identified by 1,1′-dioleyl-3,3,3′,3-tetramethylindocarbocyanine methanesulfonate fluorescence labeling. Perforated patch-clamp recordings were made from acutely dissociated DRG neurons from control and TNBS-treated rats. Pancreas-specific DRG neurons displayed more depolarized resting potentials in TNBS-treated rats than those in controls ( P < 0.02). Some neurons from the TNBS-treated group exhibited spontaneous firings. TNBS-induced CP also resulted in a dramatic reduction in rheobase ( P < 0.05) and a significant increase in the number of action potentials evoked at twice rheobase ( P < 0.05). Under voltage-clamp conditions, neurons from both groups exhibited transient A-type ( IA) and sustained outward rectifier K+ currents ( IK). Compared with controls, the average IA but not the average IK density was significantly reduced in the TNBS-treated group ( P < 0.05). The steady-state inactivation curve for IA was displaced by ∼20 mV to more hyperpolarized levels after the TNBS treatment. These data suggest that TNBS treatment increases the excitability of pancreas-specific DRG neurons by suppressing IA density, thus identifying for the first time a specific molecular mechanism underlying chronic visceral pain and sensitization in CP.
Bombesin, but not amylin, blocks the orexigenic effect of peripheral ghrelin
Authors: Kobelt Peter , Goebel Miriam , Stengel Andreas , Schmidtmann Marco , van der Voort Ivo R. , Tebbe Johannes J. , Veh Rüdiger W. , Klapp Burghard F. , Wiedenmann Bertram , Wang Lixin , Taché Yvette , Mönnikes Hubert
Published: April 2006

The interaction between ghrelin and bombesin or amylin administered intraperitoneally on food intake and brain neuronal activity was assessed by Fos-like immunoreactivity (FLI) in nonfasted rats. Ghrelin (13 μg/kg ip) increased food intake compared with the vehicle group when measured at 30 min (g/kg: 3.66 ± 0.80 vs. 1.68 ± 0.42, P < 0.0087). Bombesin (8 μg/kg) injected intraperitoneally with ghrelin (13 μg/kg) blocked the orexigenic effect of ghrelin (1.18 ± 0.41 g/kg, P < 0.0002). Bombesin alone (4 and 8 μg/kg ip) exerted a dose-related nonsignificant reduction of food intake (g/kg: 1.08 ± 0.44, P > 0.45 and 0.55 ± 0.34, P > 0.16, respectively). By contrast, ghrelin-induced stimulation of food intake (g/kg: 3.96 ± 0.56 g/kg vs. vehicle 0.82 ± 0.59, P < 0.004) was not altered by amylin (1 and 5 μg/kg ip) (g/kg: 4.37 ± 1.12, P > 0.69, and 3.01 ± 0.78, respectively, P > 0.37). Ghrelin increased the number of FLI-positive neurons/section in the arcuate nucleus (ARC) compared with vehicle (median: 42 vs. 19, P < 0.008). Bombesin alone (4 and 8 μg/kg ip) did not induce FLI neurons in the paraventricular nucleus of the hypothalamus (PVN) and coadministered with ghrelin did not alter ghrelin-induced FLI in the ARC. However, bombesin (8 μg/kg) with ghrelin significantly increased neuronal activity in the PVN approximately threefold compared with vehicle and ∼1.5-fold compared with the ghrelin group. Bombesin (8 μg/kg) with ghrelin injected intraperitoneally induced Fos expression in 22.4 ± 0.8% of CRF-immunoreactive neurons in the PVN. These results suggest that peripheral bombesin, unlike amylin, inhibits peripheral ghrelin induced food intake and enhances activation of CRF neurons in the PVN.
Vasoactive intestinal peptide stimulates mucus secretion, but nitric oxide has no effect on mucus secretion in the ferret trachea
Authors: Kim Jung-Soo , Okamoto Kosuke , Arima Shinobu , Rubin Bruce K.
Published: April 2006

Vasoactive intestinal peptide (VIP) and nitric oxide (NO) are neurotransmitters involved in the regulation of bronchial and pulmonary vascular tone. Published studies of the effects of VIP on airway mucus secretion have yielded conflicting results. The purpose of this study was to determine the effect of VIP on mucus secretion in the ferret trachea and if this effect was influenced by NO. We used a sandwich enzyme-linked lectin assay to measure mucin secretion and a turbidimetric assay to measure lysozyme (serous cell) secretion from ferret tracheal segments. VIP (10−7 M) increased mucin secretion over 2 h. VIP (10−9 to 10−5 M) stimulated mucin secretion in a dose-dependent fashion. VIP-induced mucin secretion was partially blocked by a VIP receptor antagonist (a chimeric VIP-pituitary adenylate cyclase-activating peptide analog, VIP receptor antagonist) at a 10-fold excess concentration. At all concentrations tested, neither NG-nitro-l-arginine methyl ester, an inhibitor of NO synthase, nor S-nitroso- N-acetyl-penicillamine, an NO donor, had any significant effect on constitutive or VIP-induced mucus secretion. We conclude that VIP-stimulated mucin and lysozyme secretion was both time dependent and dose dependent and that NO neither stimulates nor inhibits mucus secretion in the ferret trachea.
Models and Properties of Power-Law Adaptation in Neural Systems
Authors: Drew Patrick J. , Abbott L. F.
Published: April 2006

Many biological systems exhibit complex temporal behavior that cannot be adequately characterized by a single time constant. This dynamics, observed from single channels up to the level of human psychophysics, is often better described by power-law rather than exponential dependences on time. We develop and study the properties of neural models with scale-invariant, power-law adaptation and contrast them with the more commonly studied exponential case. Responses of an adapting firing-rate model to constant, pulsed, and oscillating inputs in both the power-law and exponential cases are considered. We construct a spiking model with power-law adaptation based on a nested cascade of processes and show that it can be “programmed” to produce a wide range of time delays. Finally, within a network model, we use power-law adaptation to reproduce long-term features of the tilt aftereffect.
Behavioral and Electromyographic Characterization of Mice Lacking EphA4 Receptors
Authors: Akay Turgay , Acharya Hernish J. , Fouad Karim , Pearson Keir G.
Published: April 2006

EphA4 receptors play an important role in axon guidance during development. Disrupting the expression of these receptors in mice has been shown to modify neuronal connections in the spinal cord and results in the production of a characteristic hopping gait. The EphA4-null mouse has been used in numerous investigations aimed at establishing mechanisms responsible for patterning motor activity during walking. However, there have been no detailed behavioral or electrophysiological studies on adult EphA4-null mice. We used high-speed video recordings to determine the coordination of leg movements during locomotion in adult EphA4-null mice. Our data show that the hopping movements of the hind legs are not always associated with synchronous movements of forelegs. The coupling between the forelegs is weak, resulting in changes in their phase relationship from step to step. The synchronous coordination of the hind legs can switch to an alternating pattern for a short period of time during recovery from isoflurane anesthesia. Comparison of the kinematics of hind leg movements in EphA4-null mice and wild-type animals shows that besides the synchronous coordination in EphA4-null mice, the swing durations and the swing amplitude are shorter. Electromyographic recordings from a knee extensor muscle show double bursting in the EphA4-null animals but single bursts in wild types. This double burst changes to single-burst activity during swimming and when hind legs are stepping in alternation. These observations suggest an influence of sensory feedback in shaping the pattern of muscle activity during locomotion in the mutant animals. Our data give the first detailed description of the locomotor behavior of an adult mouse with genetically manipulated spinal networks.
Scaling of the Fore-Aft Vestibulo-Ocular Reflex by Eye Position During Smooth Pursuit
Authors: Semrau Jennifer A. , Wei Min , Angelaki Dora
Published: April 2006

An eye position signal scales the amplitude of compensatory eye velocity in the translational vestibulo-ocular reflex (TVOR). To investigate the origin of such a modulatory signal, we studied the kinematics of the fore-aft TVOR as rhesus monkeys pursued a horizontally moving target at velocities between 0.5 and 30°/s. We found that the “V-shaped” curve of the fore-aft TVOR amplitude as a function of eye position was shifted opposite to the direction of pursuit eye movement. As a result, the tip of the V-shaped curve that occurred close to zero eye position during steady-state fixation was shifted to the right during leftward pursuit and to the left during rightward pursuit eye movements. The faster the pursuit velocity the larger the observed shift. These results suggest that the scaling of the TVOR can precede actual eye position changes by several tens of milliseconds, which averaged 169 ± 87 ms in three rhesus monkeys. Thus, central motor commands, rather than low-level efference copy or proprioceptive information, may be the signals scaling TVOR amplitude.
Opposite Perceptual and Sensorimotor Responses to a Size-Weight Illusion
Authors: Grandy Mathew S. , Westwood David A.
Published: April 2006

The perceptual size-weight illusion (SWI) occurs when two different-sized objects with equal mass are lifted in sequence: the smaller object is consistently reported to feel heavier than the larger object even after repeated lifting attempts. Here we explored the relationship between sensorimotor and perceptual responses to a SWI in which the smaller of the two target objects in fact weighed slightly less (2.7 N) than the larger object (3.2 N). For 20 consecutive lifts, participants consistently reported that the small-light object felt heavier than the large-heavy object; however, concurrently measured lifting dynamics showed exactly the opposite pattern: peak grip force, peak grip force rate, peak load force, and peak load force rate were all significantly greater for the large-heavy object versus the small-light object. The difference in peak load rate between the two objects was greatest for the initial lift but decreased significantly beyond that point, suggesting that the sensorimotor system used sensory feedback to correct for initial over- and underestimations of object mass. Despite these adjustments to lifting dynamics over the early trials, the difference between the judged heaviness of the two objects did not change. The findings clearly demonstrate that the sensorimotor and perceptual systems utilize distinctly different mechanisms for determining object mass.
Dopamine Presynaptically Depresses Fast Inhibitory Synaptic Transmission via D4 Receptor-Protein Kinase A Pathway in the Rat Dorsolateral Septal Nucleus
Authors: Asaumi Yasuo , Hasuo Hiroshi , Akasu Takashi
Published: April 2006

The lateral septal nucleus receives a diffuse dopaminergic input originating from the ventral tegmental area of the brain stem. We examined whether dopamine (DA) modulates synaptic transmission in the slice preparation of the rat dorsolateral septal nucleus (DLSN). Bath application (10–15 min) of DA (30 μM) markedly depressed the amplitude of fast and slow inhibitory postsynaptic potentials (IPSPs) in DLSN neurons, while it produced only a minor depression of the amplitude of excitatory postsynaptic potentials (EPSPs) obtained in the presence of bicuculline. DA (30 μM) depressed the monosynaptic fast IPSP to ∼50% of control, but did not depress the inward current ( IGABA) induced by exogenous γ-aminobutyric acid (GABA). DA decreased the frequency of miniature fast IPSPs (m-fIPSPs) without significantly changing their amplitude. PD 168077, a selective D4 receptor agonist, depressed the fast and slow IPSPs but not the EPSP and decreased the frequency of m-fIPSPs. Both DA and PD 168077 increased the paired-pulse ratio of the monosynaptic fast IPSP. The inhibitory effect of DA on the fast IPSP was significantly attenuated by L-741,742, an antagonist at D4 receptors, but not by SCH 23390 and sulpiride, a D1-like and a D2-like receptor antagonist, respectively. N-ethylmaleimide, a blocker of pertussis toxin (PTX)-sensitive G protein ( Gi/o), attenuated the DA-induced depression of the fast IPSP. N-[2-((p-bromocinnamyl) amino)ethyl]-5-isoquinoline sulfonamide, a protein kinase A (PKA) inhibitor, attenuated the DA-induced depression of the fast IPSP. These results suggest that DA inhibits spontaneous and evoked release of GABA via the D4 receptor- Gi-protein-PKA system in DLSN neurons.
Graded Inhibitory Synaptic Transmission Between Leech Interneurons: Assessing the Roles of Two Kinetically Distinct Low-Threshold Ca Currents
Authors: Ivanov Andrei I. , Calabrese Ronald L.
Published: April 2006

In leeches, two pairs of reciprocally inhibitory heart interneurons that form the core oscillators of the pattern-generating network for heartbeat possess both high- and low-threshold (HVA and LVA) Ca channels. LVA Ca current has two kinetically distinct components (one rapidly activating/inactivating, ICaF, and another slowly activating/inactivating, ICaS) that mediate graded transmission, generate plateau potentials driving burst formation, and modulate spike-mediated transmission between heart interneurons. Here we used different stimulating protocols and inorganic Ca channel blockers to separate the effects of ICaFand ICaSon graded synaptic transmission and determine their interaction and relative efficacy. Ca2+entering by ICaFchannels is more efficacious in mediating release than that entering by ICaSchannels. The rate of Ca2+entry by LVA Ca channels appears to be as critical as the amount of delivered Ca2+for synaptic transmission. LVA Ca currents and associated graded transmission were selectively blocked by 1 mM Ni2+, leaving spike-mediated transmission unaffected. Nevertheless, 1 mM Ni2+affected homosynaptic enhancement of spike-mediated transmission that depends on background Ca2+provided by LVA Ca channels. Ca2+provided by both ICaFand ICaSdepletes a common pool of readily releasable synaptic vesicles. The balance between availability of vesicles and Ca2+concentration and its time course determine the strength of inhibitory transmission between heart interneurons. We argue that Ca2+from multichannel domains arising from ICaFchannels, clustered near but not directly associated with the release trigger, and Ca2+radially diffusing from generally distributed ICaSchannels interact at common release sites to mediate graded transmission.
Excitatory Actions of Vasoactive Intestinal Peptide on Mouse Thalamocortical Neurons Are Mediated by VPAC2Receptors
Authors: Lee Sang-Hun , Cox Charles L.
Published: April 2006

Thalamic nuclei can generate intrathalamic rhythms similar to those observed at various arousal levels and pathophysiological conditions such as absence epilepsy. These rhythmic activities can be altered by a variety of neuromodulators that arise from brain stem regions as well as those that are intrinsic to the thalamic circuitry. Vasoactive intestinal peptide (VIP) is a neuropeptide localized within the thalamus and strongly attenuates intrathalamic rhythms via an unidentified receptor subtype. We have used transgenic mice lacking a specific VIP receptor, VPAC2, to identify its role in VIP-mediated actions in the thalamus. VIP strongly attenuated both the slow, 2–4 Hz and spindle-like 5–8 Hz rhythmic activities in slices from wild-type mice (VPAC2+/+) but not in slices from VPAC2receptor knock-out mice (VPAC2−/−), which suggests a major role of VPAC2receptors in the antioscillatory actions of VIP. Intracellular recordings revealed that VIP depolarized all relay neurons tested from VPAC2+/+mice. In VPAC2−/−mice, however, VIP produced no membrane depolarization in 80% of neurons tested. In relay neurons from VPAC2+/+ mice, VIP enhanced the hyperpolarization-activated mixed cation current, Ih, via cyclic AMP activity, but VIP did not alter Ihin VPAC2−/− mice. In VPAC2−/− mice, pituitary adenylate cyclase activating-polypeptide (PACAP) depolarized the majority of relay neurons via Ihenhancement presumably via PAC1receptor activation. Our findings suggest that VIP-mediated actions are predominantly mediated by VPAC2receptors, but PAC1receptors may play a minor role. The excitatory actions of VIP and PACAP suggest these peptides may not only regulate intrathalamic rhythmic activities, but also may influence information transfer through thalamocortical circuits.
Representation of Object Size in the Somatosensory System
Authors: Berryman L. J. , Yau J. M. , Hsiao S. S.
Published: April 2006

In this study we investigate the haptic perception of object size. We report the results from four psychophysical experiments. In the first, we ask subjects to discriminate the size of objects that vary in surface curvature and compliance while changing contact force. We show that objects exhibit size constancy such that perception of object size using haptics does not change with changes in contact force. Based on these results, we hypothesize that size perception depends on the degree of spread between the digits at initial contact with objects. In the second experiment, we test this hypothesis by having subjects continuously contact an object that changes dynamically in size. We show that size perception takes into account the compliance of the object. In the third and fourth experiments we attempt to separate the individual contributions of proprioceptive and cutaneous input. In the third, we test the ability of subjects to perceive object size after altering the sensitivity of cutaneous receptors with adapting vibratory stimuli. The results from this experiment suggest that initial contact is signaled by the cutaneous slowly adapting type 1 afferents (SA1) and/or the rapidly adapting afferents (RA). In the last experiment, we block cutaneous input at the site of contact by anesthetizing the digital nerves and show that proprioceptive information alone provides only a rough estimate of object size. We conclude that the perception of object size depends on inputs from SA1 and possibly RA afferents, combined with inputs from proprioceptive afferents that signal the spread between digits.
Compartmentation of Cyclic Nucleotide Signaling in the Heart
Authors: Dodge-Kafka Kimberly L. , Langeberg Lorene , Scott John D.
Published: April 2006

The activation of the cyclic nucleotide protein kinase A (PKA) and PKG by their respective second messengers is responsible for the modulation of many cellular functions in the heart including cardiac hypertrophy, strength of contraction, and ion flux. However, several studies have revealed that a general increase in cyclic nucleotide concentration in the cell is not sufficient for the specific regulation of target proteins. These studies found that PKA and PKG must be colocalized with their targets to ensure spatial–temporal control of substrate phosphorylation. This compartmentation of cyclic nucleotide signaling is accomplished by tethering the protein kinases with their respective substrates through the association with scaffolding proteins. For cAMP signaling, A-kinase anchoring proteins (AKAPs) provide a molecular mechanism for cAMP compartmentation, allowing for the precise control of PKA-mediated phosphorylation events. (cAMP, PKA, AKAP, PKG).
On the Coupling of Wind Stress and Sea Surface Temperature
Authors: Samelson R. M. , Skyllingstad E. D. , Chelton D. B. , Esbensen S. K. , O'Neill L. W. , Thum N.
Published: April 2006

A simple quasi-equilibrium analytical model is used to explore hypotheses related to observed spatial correlations between sea surface temperatures and wind stress on horizontal scales of 50–500 km. It is argued that a plausible contributor to the observed correlations is the approximate linear relationship between the surface wind stress and stress boundary layer depth under conditions in which the stress boundary layer has come into approximate equilibrium with steady free-atmospheric forcing. Warmer sea surface temperature is associated with deeper boundary layers and stronger wind stress, while colder temperature is associated with shallower boundary layers and weaker wind stress. Two interpretations of a previous hypothesis involving the downward mixing of horizontal momentum are discussed, and it is argued that neither is appropriate for the warm-to-cold transition or quasi-equilibrium conditions, while one may be appropriate for the cold-to-warm transition. Solutions of a turbulent large-eddy simulation numerical model illustrate some of the processes represented in the analytical model. A dimensionless ratio γτA is introduced to measure the relative influence of lateral momentum advection and local surface stress on the boundary layer wind profile. It is argued that when γτA < 1, and under conditions in which the thermodynamically induced lateral pressure gradients are small, the boundary layer depth effect will dominate lateral advection and control the surface stress.
Influence of “Realistic” Land Surface Wetness on Predictability of Seasonal Precipitation in Boreal Summer
Authors: Kanae Shinjiro , Hirabayashi Yukiko , Yamada Tomohito , Oki Taikan
Published: April 2006

Outputs from two ensembles of atmospheric model simulations for 1951–98 define the influence of “realistic” land surface wetness on seasonal precipitation predictability in boreal summer. The ensembles consist of one forced with observed sea surface temperatures (SSTs) and the other forced with realistic land surface wetness as well as SSTs. Predictability was determined from correlations between the time series of simulated and observed precipitation. The ratio of forced variance to total variance determined potential predictability. Predictability occurred over some land areas adjacent to tropical oceans without land wetness forcing. On the other hand, because of the chaotic nature of the atmosphere, considerable parts of the land areas of the globe did not even show potential predictability with both land wetness and SST forcings.

The use of land wetness forcing enhanced predictability over semiarid regions. Such semiarid regions are generally characterized by a negative correlation between fluxes of latent heat and sensible heat from the land surface, and are “water-regulating” areas where soil moisture plays a governing role in land–atmosphere interactions. Actual seasonal prediction may be possible in these regions if slowly varying surface conditions can be estimated in advance. In contrast, some land regions (e.g., south of the Sahel, the Amazon, and Indochina) showed little predictability despite high potential predictability. These regions are mostly characterized by a positive correlation between the surface fluxes, and are “radiation-regulating” areas where the atmosphere plays a leading role. Improvements in predictability for these regions may require further improvements in model physics.
Bulk Recycling Models with Incomplete Vertical Mixing. Part I: Conceptual Framework and Models
Authors: Burde Georgy I.
Published: April 2006

A conceptual framework, within which the bulk recycling models could incorporate the effects related to an incomplete vertical mixing of water in the tropospheric column, is developed. As an example, the bulk model with the modified well-mixed atmosphere condition, incorporating the “fast recycling” process, is constructed. The model contains a tunable, spatially varying parameter K that characterizes the level of the incomplete vertical mixing effects. The simplified analytical models based on the modified well-mixed atmosphere condition are developed. The analysis of the simplified model results shows that the regional recycling ratio may depend significantly on the average of K, but it depends only slightly on the rate of variation of K, which indicates that models with a constant K can be used instead of the variable K model.
Maintenance of the Boreal Forest Rainbelts during Northern Summer
Authors: Yoon Jin-Ho , Chen Tsing-Chang
Published: April 2006

It is not unreasonable to expect that boreal forests that exist along 60°N in the Eurasian and North American continents were created and are maintained by warm seasonal rainfall. As revealed from satellite observations and various precipitation sources, zonally elongated rainbelts appear along these forests. Previous studies show that a relationship may exist between the frontal zone along the Arctic seaboard and regional patterns of high-latitude precipitation. It was observed by this study that baroclinic zones associated with strong Arctic westerlies coincide with minor storm tracks and boreal forest rainbelts only in eastern Canada. In contrast, this coincidence does not occur in northern Europe, eastern Siberia, and the Alaska–Pacific coast, because boreal forest rainbelts in these regions are located farther south of strong Arctic westerlies and ahead of high-latitude troughs over central Eurasia, the Bering Sea, the Labrador Sea, and the Norwegian Sea. Therefore, instead of baroclinicity along strong Arctic westerlies, favorable environments for the formation of minor storm tracks are developed by positive vorticity advections ahead of these high-latitude troughs. The water vapor budget analyses performed with NCEP and Goddard Earth Observing System (GEOS-1) reanalyses show that the boreal forest rainbelts are essentially maintained by the convergence of water vapor flux associated with transient disturbances at high latitudes.
Trends in Total and Extreme South American Rainfall in 1960–2000 and Links with Sea Surface Temperature
Authors: Haylock M. R. , Peterson T. C. , Alves L. M. , Ambrizzi T. , Anunciação Y. M. T. , Baez J. , Barros V. R. , Berlato M. A. , Bidegain M. , Coronel G. , Corradi V. , Garcia V. J. , Grimm A. M. , Karoly D. , Marengo J. A. , Marino M. B. , Moncunill D. F. , Nechet D. , Quintana J. , Rebello E. , Rusticucci M. , Santos J. L. , Trebejo I. , Vincent L. A.
Published: April 2006

A weeklong workshop in Brazil in August 2004 provided the opportunity for 28 scientists from southern South America to examine daily rainfall observations to determine changes in both total and extreme rainfall. Twelve annual indices of daily rainfall were calculated over the period 1960 to 2000, examining changes to both the entire distribution as well as the extremes. Maps of trends in the 12 rainfall indices showed large regions of coherent change, with many stations showing statistically significant changes in some of the indices. The pattern of trends for the extremes was generally the same as that for total annual rainfall, with a change to wetter conditions in Ecuador and northern Peru and the region of southern Brazil, Paraguay, Uruguay, and northern and central Argentina. A decrease was observed in southern Peru and southern Chile, with the latter showing significant decreases in many indices. A canonical correlation analysis between each of the indices and sea surface temperatures (SSTs) revealed two large-scale patterns that have contributed to the observed trends in the rainfall indices. A coupled pattern with ENSO-like SST loadings and rainfall loadings showing similarities with the pattern of the observed trend reveals that the change to a generally more negative Southern Oscillation index (SOI) has had an important effect on regional rainfall trends. A significant decrease in many of the rainfall indices at several stations in southern Chile and Argentina can be explained by a canonical pattern reflecting a weakening of the continental trough leading to a southward shift in storm tracks. This latter signal is a change that has been seen at similar latitudes in other parts of the Southern Hemisphere. A similar analysis was carried out for eastern Brazil using gridded indices calculated from 354 stations from the Global Historical Climatology Network (GHCN) database. The observed trend toward wetter conditions in the southwest and drier conditions in the northeast could again be explained by changes in ENSO.
A Climatological Monsoon Break in Rainfall over Indochina—A Singularity in the Seasonal March of the Asian Summer Monsoon
Authors: Takahashi Hiroshi G. , Yasunari Tetsuzo
Published: April 2006

This study investigated the climatological pentad mean annual cycle of rainfall in Thailand and the associated atmospheric circulation fields. The data used included two different data of rainfall: rain gauge data for Thailand from the Thai Meteorological Department and satellite-derived rainfall data from the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP).

Climatological mean pentad values of rainfall taken over 50 yr clearly show a distinct climatological monsoon break (CMB) occurring over Thailand in late June. The occurrence of the CMB coincides with a drastic change of large-scale monsoon circulation in the seasonal march. The CMB is a significant singularity in the seasonal march of the Southeast Asia monsoon, which divides the rainy season into the early monsoon and the later monsoon over the Indochina Peninsula.

A quasi-stationary ridge dynamically induced by the north–south-oriented mountain range in Indochina is likely to cause the CMB. The formation of the strong ridge over the mountain ranges of Indochina is preceded by a sudden enhancement (northward expansion) of the upstream monsoon westerlies along a latitudinal band between 15° and 20°N in late June. The CMB also has an impact downstream. The orographically induced stationary Rossby waves enhance the cyclonic circulation to the lee of Indochina, and over the South China Sea. The enhancement of cyclonic circulation may be responsible for the summer monsoon rains peaking in late June over the South China Sea and the western North Pacific, and in the baiu front.
Effects of Averaging and Separating Soil Moisture and Temperature in the Presence of Snow Cover in a SVAT and Hydrological Model for a Southern Ontario, Canada, Watershed
Authors: Fassnacht S. R. , Yang Z-L. , Snelgrove K. R. , Soulis E. D. , Kouwen N.
Published: April 2006

The energy and water balances at the earth's surface are dramatically influenced by the presence of snow cover. Therefore, soil temperature and moisture for snow-covered and snow-free areas can be very different. In computing these soil state variables, many land surface schemes in climate models do not explicitly distinguish between snow-covered and snow-free areas. Even if they do, some schemes average these state variables to calculate grid-mean energy fluxes and these averaged state variables are then used at the beginning of the next time step. This latter approach introduces a numerical error in that heat is redistributed from snow-free areas to snow-covered areas, resulting in a more rapid snowmelt. This study focuses on the latter approach and examines the sensitivity of soil moisture and streamflow to the treatment of the soil state variables in the presence of snow cover by using WATCLASS, a land surface scheme linked with a hydrologic model. The model was tested for the 1993 snowmelt period on the Upper Grand River in Southern Ontario, Canada. The results show that a more realistic simulation of streamflow can be obtained by keeping track of the soil states in snow-covered and snow-free areas.
Passive Acoustic Determination of Wave-Breaking Events and Their Severity across the Spectrum
Authors: Manasseh Richard , Babanin Alexander V. , Forbes Cameron , Rickards Kate , Bobevski Irena , Ooi Andrew
Published: April 2006

A passive acoustic method of detecting breaking waves of different scales has been developed. The method also showed promise for measuring breaking severity.

Sounds were measured by a subsurface hydrophone in various wind and wave states. A video record of the surface was made simultaneously. Individual sound pulses corresponding to the many individual bubble formations during wave-breaking events typically last only a few tens of milliseconds. Each time a sound-level threshold was exceeded, the acoustic signal was captured over a brief window typical of a bubble formation pulse, registering one count. Each pulse was also analyzed to determine the likely bubble size generating the pulse.

Using the time series of counts and visual observations of the video record, the sound-level threshold that detected bubble formations at a rate optimally discriminating between breaking and nonbreaking waves was determined by a classification-accuracy analysis. This diagnosis of breaking waves was found to be approximately 70%–75% accurate once the optimum threshold had been determined.

The method was then used for detailed analysis of wave-breaking properties across the spectrum. When applied to real field data, a breaking probability distribution could be obtained. This is the rate of occurrence of wave-breaking events at different wave scales. With support from a separate, laboratory experiment, the estimated bubble size is argued to be dependent on the severity of wave breaking and thus to provide information on the energy loss due to the breaking at the measured spectral frequencies. A combination of the breaking probability distribution and the bubble size could lead to direct estimates of spectral distribution of wave dissipation.
Low-Frequency Sea Level Variability and the Inverted Barometer Effect
Authors: Ponte Rui M.
Published: April 2006

For a dynamical interpretation of sea level records, estimates are needed of the isostatic, or so-called inverted barometer, signals (ηib) associated with the ocean response to atmospheric loading. Seasonal and longer-period ηib signals are evaluated over the global ocean for the period 1958–2000 using monthly sea level pressure fields from two different atmospheric reanalyses. Variability and linear trends in ηib agree well for the two reanalyses in most regions but less so over the Southern Ocean, where uncertainties in ηib seem to be largest. The standard deviation of ηib ranges from <1 cm in equatorial regions to >7 cm in the regions of the Aleutian and Iceland lows and parts of the Southern and Arctic Oceans. When compared to a global tide gauge dataset, both seasonal and interannual ηib signals are found to contribute importantly to the sea level variance in many mid- and high-latitude records, with seasonal signals important as well in tropical records from India and Southeast Asia. For these records, subtracting ηib from the data can lead to changes in variance of 40% or more. Over the period of study, linear trends in ηib are mostly negative at low and midlatitudes and can cause negative biases in tide gauge estimates of global mean sea level rise that are comparable in magnitude to the effects of postglacial rebound. In agreement with previous findings, ηib signals are found to introduce anomalous behavior in local records (e.g., substantially weaker upward trends in the Mediterranean), and their removal can also reduce formal trend uncertainties. Accounting for ηib effects can be even more important when analyzing relatively short (decadal) records, such as those available from satellite altimetry.
Phased-Array Design for Biological Clutter Rejection: Simulation and Experimental Validation
Authors: Cheong B. L. , Hoffman M. W. , Palmer R. D. , Frasier Stephen J. , López-Dekker F. J.
Published: April 2006

This paper highlights recent results obtained with the Turbulent Eddy Profiler (TEP), which was developed by the University of Massachusetts. This unique 915-MHz radar has up to 64 spatially separated receiving elements, each with an independent receiver. The calibrated raw data provided by this array could be processed using sophisticated imaging algorithms to resolve the horizontal structures within each range gate. After collecting all of the closely spaced horizontal slices, the TEP radar can produce three-dimensional images of echo power, radial velocity, and spectral width. From the radial velocity measurements, it is possible to estimate the three-dimensional wind with high horizontal and vertical resolution. Given the flexibility of the TEP system, various array configurations are possible. In the present work exploitation of the flexibility of TEP is attempted to enhance the rejection of clutter from unwanted biological targets. From statistical studies, most biological clutter results from targets outside the main imaging field of view, that is, the sidelobes and grating lobes (if they exist) of the receiving beam. Because the TEP array's minimum receiver separation exceeds the spatial Nyquist sampling requirement, substantial possibilities for grating-lobe clutter exist and are observed in actual array data. When imaging over the transmit beam volume, the receiving array main lobe is scanned over a ±12.5° region. This scanning also sweeps the grating lobes over a wide angular region, virtually guaranteeing that a biological scatterer outside of the main beam will appear somewhere in the imaged volume. This paper focuses on suppressing pointlike targets in the grating-lobe regions. With a subtle change to the standard TEP array hardware configuration, it is shown via simulations and actual experimental observations (collected in June 2003) that adaptive beamforming methods can subsequently be used to significantly suppress the effects of point targets on the wind field estimates. These pointlike targets can be birds or planes with strong reflectivity. By pointlike the authors mean its appearance is a distinct point (up to the imaging resolution) in the images. The pointlike strong reflectivity signature exploits the capability of adaptive beamforming to suppress the interference using the new array configuration. It should be noted that this same array configuration does not exhibit this beneficial effect when standard Fourier beamforming is employed.
Continuous Humidity Monitoring in a Tropical Region with the Equatorial Atmosphere Radar
Authors: Furumoto Jun-ichi , Tsuda Toshitaka , Iwai Satoshi , Kozu Toshiaki
Published: April 2006

A radar remote sensing technique that estimates humidity profiles using a wind profiler is applied to the equatorial atmosphere radar (EAR) to monitor detailed humidity variations in tropical regions. Turbulence echo power intensity is related to the vertical refractive index gradient squared (M2). Here, M is primarily determined by the vertical gradient of specific humidity in the lower troposphere. These relations are employed to estimate a humidity profile.

EAR is a 47-MHz very high frequency (VHF) atmospheric radar installed at KotoTabang in West Sumatra, Indonesia. A humidity-profiling method, which was recently developed for the middle- and upper-atmosphere (MU) radar, was applied to EAR. The aim was to test this new method with a larger dataset observed in the tropical region, where detailed humidity variations have not been fully revealed. EAR observations were carried out in November 2002. Turbulence echoes from one vertical and four oblique beams were obtained with time and height resolutions of 3 min and 150 m, respectively. Spano and Ghebrebrhan's optimized 16-bit code was used for EAR in the entire height range in order to increase the signal-to-noise ratio of the turbulence observation. The effects of pulse compression and coherent and incoherent integrations were removed from the echo power intensity. Because the echo power intensity with the vertical beam was affected by partial reflection, M2 was averaged over four oblique beams.

The humidity profiles were estimated using EAR at heights of 1.5–7.5 km. Below 3.0 km the sensitivity of the EAR receiver decreased and the radar-derived |M| was also reduced. Thus, the radar-derived |M| below 3.0 km was adjusted by multiplying the reduction factor calculated from the comparisons with radiosonde results in the campaign period. In this analysis, time-interpolated temperature profiles of radiosonde observations were used to estimate humidity profiles. Detailed variations of humidity corresponded well to rain distribution observed simultaneously with the L-band boundary layer radar (BLR) and the X-band radar, and to the cloud bottom height observed with a ceilometer.
IAC ETH Goniospectrometer: A Tool for Hyperspectral HDRF Measurements
Authors: Bourgeois C. Saskia , Ohmura Atsumu , Schroff Karl , Frei Hans-Jörg , Calanca Pierluigi
Published: April 2006

This work presents a new field goniospectrometer developed at the Institute for Atmospheric and Climate Science (IAC) of the Swiss Federal Institute of Technology (ETH; Switzerland). The goniospectrometer was built to study the hemispherical directional reflectance factor (HDRF) of snow, but can also be applied to other surfaces with moderate surface roughness.

The IAC ETH goniospectrometer measures HDRFs with high spatial resolution. The goniometer is exclusively built of straight parts, thus ensuring a high pointing accuracy. The two robotic arms are controlled automatically with step motors, whereby the step size can be defined by the user. With the default grid size of 15° in zenith and azimuth, the time needed to collect one complete HDRF dataset is 11 min, corresponding to a change of less than 4° in solar zenith and azimuth angles.

The spectrometer comprises two probes. The first probe is equipped with a 3° foreoptic and is used for taking a spectrum of the reflected radiance; the second is placed on a tripod, has a 2π foreoptic, and simultaneously records a spectrum of the incoming irradiance. Both probes measure in the spectral range from 350 to 1050 nm, with a resolution of approximately 3 nm at around 700 nm.

The performance of the new goniospectrometer was tested at the Greenland Environmental Observatory Summit Station (72°35′N, 34°30′W, 3203 m ASL) during the summer of 2004.
Introduction
Authors: Riggio Heidi R.
Published: April 2006

The increasing entrance of women into the American workforce during the past few decades is undoubtedly one of the greatest societal changes Americans have experienced, with important effects on family structure, dynamics, and the social and psychological development of individual family members. This second part of a double issue presents research investigating but a few of the myriad effects of changes in the workforce on the family, including outcomes for children and their mothers, as well as issues of growing concern for dual-earner families. Articles in this issue focus on the identities of working mothers; outcomes of maternal employment for children, including attitudes toward work and family in young adulthood; concerns about after-school care and retirement planning within dual-earner families; and community responsiveness to working families.
A Long-Term Investigation of the Role of Maternal and Dual-Earner Employment in Children's Development
Authors: Gottfried Adele Eskeles , Gottfried Allen W.
Published: April 2006

This article presents an overview of the major issues investigated in a longitudinal study of development from infancy through early adulthood regarding the relationships between maternal and dual-earner employment and children's development. Based on the results of this extensive and long-term study, as well as integrating the results of other researchers, the authors advance a developmental impingement and family adaptation perspective to guide the interpretation of research findings as well as to formulate new research directions. Maternal and dual-earner employment can best be understood in the context of the multiplicity of factors that exist in the child's environment.
Antecedents and Correlates of Parental After-School Concern
Authors: Barnett Rosalind Chait , Gareis Karen C.
Published: April 2006

Employed parents' concern about their children's welfare after school (PCAST) has been linked to psychological well-being. To explore the risk factors for PCAST, the authors estimate the effects of parent job flexibility and commuting time, child time unsupervised after school, and partner after-school availability on PCAST in a sample of 243 parents employed at a financial services company. Because parents with high PCAST are likely to be distracted at work, the authors also examine the effects of PCAST on job performance. For mothers and fathers alike, PCAST is predicted by job flexibility and by child time unsupervised after school, and PCAST is a significant predictor of job disruptions.
Community Contexts
Authors: Pitt-Catsouphes Marcie , MacDermid Shelley M. , Schwarz Rona , Matz Christina
Published: April 2006

This article discusses the importance of considering communities to be important social contexts for working families. The Nurturing Families Study gathered data from 357 working parents and their children in Grades 6 to 8 who lived in six different U.S. communities. The study protocols included items that measured parents'subjective assessments of important social contexts, including families' communities of residence. Data were collected about parents' perceptions of programs and services in their communities, neighborhood relationships, family-supportive community policies, community values that welcome diverse families, and overall satisfaction with neighborhoods and communities. Analysis of data collected about parents'subjective assessments of their neighborhoods and communities indicate relationships between parents' assessments of different dimensions of their communities and important work-family outcome measures, such as general family functioning and life satisfaction.