bluuebunny/crossref_metadata_2025 huggingface dataset:
Porphyry and Plotinus on the Seed
Authors: Wilberding James
Published: September 2008

Porphyry's account of the nature of seeds can shed light on some less appreciated details of Neoplatonic psychology, in particular on the interaction between individual souls. The process of producing the seed and the conception of the seed offer a physical instantiation of procession and reversion, activities that are central to Neoplatonic metaphysics. In an act analogous to procession, the seed is produced by the father's nature, and as such it is ontologically inferior to the father's nature. Thus, the seed does not strictly speaking contain a full-fledged vegetative soul. Rather, it acquires its vegetative soul only while it is being actualized by an actual vegetative soul. This actualization takes place primarily at conception, where the seed as it were reverts back and becomes obedient to the mother's nature, but continues through the period of gestation. In this way, Porphyry can account both for maternal resemblance and for ideoplasty. He uses the Stoic language of complete blending to describe the mother's relation to the seed and embryo, and this reveals that he thinks of individuals as having their own unique individual natures (as opposed to sharing in a single universal nature). In the course of developing this theory, Porphyry makes significant revisions to his philosophical predecessors' views in both embryology and botany. He revises Aristotle's verdict on the relative importance of the female in generation as well as Theophrastus' explanation of the biological mechanics of grafting. Although Plotinus nowhere addresses embryology in the same detail as Porphyry does, we can conclude from his remarks on seeds and plants that his own views were similar to those of his student.
Interpreting the Atmospheric Circulation Trend during the Last Half of the Twentieth Century: Application of an Adjoint Model
Authors: Blessing Simon , Greatbatch Richard J. , Fraedrich Klaus , Lunkeit Frank
Published: September 2008

A tangent linear adjoint for a low-resolution dynamical model of the atmosphere is used to derive the optimal forcing perturbations for all state variables such that after a specified lead time the model response has a given projection, in terms of an energy norm, on the pattern associated with the 51-yr trend in the Northern Hemisphere winter tropospheric circulation, 1948/49–1998/99. A feature of the derived forcing sensitivity is a Rossby wave–like feature that emanates from the western tropical Pacific and is associated with the deepening of the Aleutian low, whereas an annular pattern in the forcing sensitivity in the uppermost model level is shown to be associated with the pattern of the trend over the Euro-Atlantic/Asian sectors, including the upward trend in the North Atlantic Oscillation index. The authors argue that the Rossby wave–type feature is consistent with studies that have argued a role for the upward trend in tropical sea surface temperature during the 51-yr period. On the other hand, the authors interpret the annular pattern in the forcing sensitivity as being consistent with studies that have argued that the trend over the Euro-Atlantic sector was associated with influences from the stratosphere. In particular, a nonlinear model driven by the optimal forcing perturbation applied only to the top model level is successful at reproducing the trend pattern with the correct amplitude in the Euro-Atlantic sector, but implies a trend over the North Pacific toward a weaker Aleutian low, contrary to what was observed but similar to the spatial pattern associated with the northern annular mode. These results show that the adjoint approach can shed light on previous apparently different interpretations of the trend. The study also presents a successful application of a tangent linear adjoint model to a climate problem.
Internal Feedbacks from Monsoon–Midlatitude Interactions during Droughts in the Indian Summer Monsoon
Authors: Krishnan R. , Kumar Vinay , Sugi M. , Yoshimura J.
Published: September 2008

Results from a 20-yr simulation of a high-resolution AGCM forced with climatological SST, along with simplified model experiments and supplementary data diagnostics, are used to investigate internal feedbacks arising from monsoon–midlatitude interactions during droughts in the Indian summer monsoon. The AGCM simulation not only shows a fairly realistic mean monsoon rainfall distribution and large-scale circulation features but also exhibits remarkable interannual variations of precipitation over the subcontinent, with the 20-yr run showing incidence of four “monsoon droughts.”

The present findings indicate that the internally forced droughts in the AGCM emanate largely from prolonged “monsoon breaks” that occur on subseasonal time scales and involve dynamical feedbacks between monsoon convection and extratropical circulation anomalies. In this feedback, the suppressed monsoon convection is shown to induce Rossby wave dispersion in the summertime subtropical westerlies and to set up an anomalous quasi-stationary circulation pattern extending across continental Eurasia in the middle and upper troposphere. This pattern is composed of a cyclonic anomaly over west central Asia and the Indo-Pakistan region, a meridionally deep anticyclonic anomaly over East Asia (∼100°E), and a cyclonic anomaly over the Far East. The results suggest that the anchoring of the west central Asia cyclonic anomaly by the stagnant ridge located downstream over East Asia induces anomalous cooling in the middle and upper troposphere through cold-air advection, which reduces the meridional thermal contrast over the subcontinent. Additionally, the intrusion of the dry extratropical winds into northwest India can decrease the convective instability, so that the suppressed convection can in turn weaken the monsoon flow. The sustenance of monsoon breaks through such monsoon–midlatitude feedbacks can generate droughtlike conditions over India.
Sensitivity of the Upper Mesosphere to the Lorenz Energy Cycle of the Troposphere
Authors: Becker Erich
Published: September 2008

The concept of a mechanistic general circulation model that explicitly simulates the gravity wave drag in the extratropical upper mesosphere in a self-consistent fashion is proposed. The methodology consists of 1) a standard spectral dynamical core with high resolution, 2) idealized formulations of radiative and latent heating, and 3) a hydrodynamically consistent turbulent diffusion scheme with the diffusion coefficients based on Smagorinsky’s generalized mixing-length formulation and scaled by the Richardson criterion. The model reproduces various mean and variable features of the wave-driven general circulation from the boundary layer to the mesopause region during January.

The dissipation of mesoscale kinetic energy (defined as the frictional heating due to the mesoscale flow) in the extratropical troposphere is found to indicate the tropospheric gravity wave sources relevant for the mesosphere/lower thermosphere. This motivates a sensitivity experiment in which the large-scale differential heating is perturbed such that the Lorenz energy cycle as measured by the globally integrated frictional heating becomes stronger. As a result, both the resolved gravity wave activity and the dissipation of mesoscale kinetic energy in the extratropical troposphere are amplified. These changes have strong remote effects in the summer mesopause region, where the gravity wave drag, the residual meridional wind, and the frictional heating shift to lower altitudes. Furthermore, temperatures decrease below the summer mesopause and increase farther up, which is accompanied by an anomalous eastward wind component around the mesopause.
Life Cycles of Hurricane-Like Vorticity Rings
Authors: Hendricks Eric A. , Schubert Wayne H. , Taft Richard K. , Wang Huiqun , Kossin James P.
Published: September 2008

The asymmetric dynamics of potential vorticity mixing in the hurricane inner core are further advanced by examining the end states that result from the unforced evolution of hurricane-like vorticity rings in a nondivergent barotropic model. The results from a sequence of 170 numerical simulations are summarized. The sequence covers a two-dimensional parameter space, with the first parameter defining the hollowness of the vortex (i.e., the ratio of eye to inner-core relative vorticity) and the second parameter defining the thickness of the ring (i.e., the ratio of the inner and outer radii of the ring). In approximately one-half of the cases, the ring becomes barotropically unstable, and there ensues a vigorous vorticity mixing episode between the eye and eyewall. The output of the barotropic model is used to (i) verify that the nonlinear model approximately replicates the linear theory of the fastest-growing azimuthal mode in the early phase of the evolution, and (ii) characterize the end states (defined at t = 48 h) that result from the nonlinear chaotic vorticity advection and mixing. It is found that the linear stability theory is a good guide to the fastest-growing exponential mode in the numerical model. Two additional features are observed in the numerical model results. The first is an azimuthal wavenumber-2 deformation of the vorticity ring that occurs for moderately thick, nearly filled rings. The second is an algebraically growing wavenumber-1 instability (not present in the linear theory because of the assumed solution) that is observed as a wobbling eye (or the trochoidal oscillation for a moving vortex) for thick rings that are stable to all exponentially growing instabilities. Most end states are found to be monopoles. For very hollow and thin rings, persistent mesovortices may exist for more than 15 h before merging to a monopole. For thicker rings, the relaxation to a monopole takes longer (between 48 and 72 h). For moderately thick rings with nearly filled cores, the most likely end state is an elliptical eyewall. In this nondivergent barotropic context, both the minimum central pressure and maximum tangential velocity simultaneously decrease over 48 h during all vorticity mixing events.
Internal Atmospheric Variability and Interannual-to-Decadal ENSO Variability in a CGCM
Authors: Yeh Sang-Wook , Kirtman Ben P.
Published: September 2008

The interactive ensemble coupling strategy has been developed specifically to determine how noise due to internal atmosphere dynamics impacts climate variability within the context of coupled general circulation models (CGCMs). In this study the authors investigate the impact of internal atmospheric variability on the ENSO variability using four CGCM simulations. In the control simulation, the interactive ensemble strategy is applied globally, thereby reducing the noise at the air–sea interface at each ocean grid point. In the second and third CGCM simulations, the interactive ensemble strategy is applied locally in the extratropics versus the tropics only, respectively. In addition, those results were compared with a standard CGCM.

The results suggest that tropical internal atmospheric variability strengthens the interannual-to-decadal ENSO variability and leads to a broader spectral peak. However, the noise due to internal atmospheric dynamics plays different roles when the interannual and decadal ENSO variability is considered separately. There are noise-induced changes in the SST–zonal wind stress feedbacks from interannual to decadal time scales. The tropical atmospheric internal variability largely modifies the frequency as opposed to the amplitude of the ENSO variability on interannual time scales. In contrast, tropical internal atmospheric variability is effective in forcing decadal ENSO variability, resulting in a significant decrease of decadal ENSO amplitude in the central tropical Pacific in a CGCM when the noise is reduced. The authors argue that the decadal ENSO variability is directly affected by the low-frequency noise over the western part of the tropical Pacific in a linear sense. On the other hand, the impact of extratropical atmospheric noise on the ENSO variability is weaker than the noise in the tropics.
North Pacific Climate Response to Freshwater Forcing in the Subarctic North Atlantic: Oceanic and Atmospheric Pathways
Authors: Okumura Yuko M. , Deser Clara , Hu Aixue , Timmermann Axel , Xie Shang-Ping
Published: September 2008

Sudden changes of the Atlantic meridional overturning circulation (AMOC) are believed to have caused large, abrupt climate changes over many parts of the globe during the last glacial and deglacial period. This study investigates the mechanisms by which a large freshwater input to the subarctic North Atlantic and an attendant rapid weakening of the AMOC influence North Pacific climate by analyzing four different ocean–atmosphere coupled general circulation models (GCMs) under present-day or preindustrial boundary conditions. When the coupled GCMs are forced with a 1-Sv (Sv ≡ 106 m3 s−1) freshwater flux anomaly in the subarctic North Atlantic, the AMOC nearly shuts down and the North Atlantic cools significantly. The South Atlantic warms slightly, shifting the Atlantic intertropical convergence zone southward. In addition to this Atlantic ocean–atmosphere response, all of the models exhibit cooling of the North Pacific, especially along the oceanic frontal zone, consistent with paleoclimate reconstructions. The models also show deepening of the wintertime Aleutian low.

Detailed analysis of one coupled GCM identifies both oceanic and atmospheric pathways from the Atlantic to the North Pacific. The oceanic teleconnection contributes a large part of the North Pacific cooling: the freshwater input to the North Atlantic raises sea level in the Arctic Ocean and reverses the Bering Strait throughflow, transporting colder, fresher water from the Arctic Ocean into the North Pacific. When the Bering Strait is closed, the cooling is greatly reduced, while the Aleutian low response is enhanced. Tropical SST anomalies in both the Atlantic and Pacific are found to be important for the equivalent barotropic response of the Aleutian low during boreal winter. The atmospheric bridge from the tropical North Atlantic is particularly important and quite sensitive to the mean state, which is poorly simulated in many coupled GCMs. The enhanced Aleutian low, in turn, cools the North Pacific by increasing surface heat fluxes and southward Ekman transport. The closure of the Bering Strait during the last glacial period suggests that the atmospheric bridge from the tropics and air–sea interaction in the North Pacific played a crucial role in the AMOC–North Pacific teleconnection.
Temperature and Melt Modeling on the Prince of Wales Ice Field, Canadian High Arctic
Authors: Marshall Shawn J. , Sharp Martin J.
Published: September 2008

Near-surface temperature variability and net annual mass balance were monitored from May 2001 to April 2003 in a network of 25 sites on the Prince of Wales Ice Field, Ellesmere Island, Canada. The observational array spanned an area of 180 km by 120 km and ranged from 130 to 2010 m in altitude. Hourly, daily, and monthly average temperatures from the spatial array provide a record of mesoscale temperature variability on the ice field. The authors examine seasonal variations in the variance of monthly and daily temperature: free parameters in positive-degree-day melt models that are presently in use for modeling of glacier mass balance. An analysis of parameter space reveals that daily and seasonal temperature variability are suppressed in summer months (over a melting snow–ice surface), an effect that is important to include in melt modeling. In addition, average annual vertical gradients in near-surface temperature were −3.7°C km−1 in the 2-yr record, steepening to −4.4°C km−1 in the summer months. These gradients are less than the adiabatic lapse rates that are commonly adopted for extrapolation of sea level temperature to higher altitudes, with significant implications for modeling of snow and ice melt. Mass balance simulations for the ice field illustrate the sensitivity of melt models to different lapse rate and temperature parameterizations.
Statistical Evaluation of Combined Daily Gauge Observations and Rainfall Satellite Estimates over Continental South America
Authors: Vila Daniel A. , de Goncalves Luis Gustavo G. , Toll David L. , Rozante Jose Roberto
Published: September 2008

This paper describes a comprehensive assessment of a new high-resolution, gauge–satellite-based analysis of daily precipitation over continental South America during 2004. This methodology is based on a combination of additive and multiplicative bias correction schemes to get the lowest bias when compared with the observed values (rain gauges). Intercomparisons and cross-validation tests have been carried out between independent rain gauges and different merging techniques. This validation process was done for the control algorithm [Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis real-time algorithm] and five different merging schemes: additive bias correction; ratio bias correction; TRMM Multisatellite Precipitation Analysis, research version; and the combined scheme proposed in this paper. These methodologies were tested for different months belonging to different seasons and for different network densities. All compared, merging schemes produce better results than the control algorithm; however, when finer temporal (daily) and spatial scale (regional networks) gauge datasets are included in the analysis, the improvement is remarkable. The combined scheme consistently presents the best performance among the five techniques tested in this paper. This is also true when a degraded daily gauge network is used instead of a full dataset. This technique appears to be a suitable tool to produce real-time, high-resolution, gauge- and satellite-based analyses of daily precipitation over land in regional domains.
Modeling the Response of Canopy Stomatal Conductance to Humidity
Authors: Wang Shusen , Yang Yan , Trishchenko Alexander P. , Barr Alan G. , Black T. A. , McCaughey Harry
Published: September 2008

Humidity of air is a key environmental variable in controlling the stomatal conductance (g) of plant leaves. The stomatal conductance–humidity relationships employed in the Ball–Woodrow–Berry (BWB) model and the Leuning model have been widely used in the last decade. Results of independent evaluations of the two models vary greatly. In this study, the authors develop a new diagnostic parameter that is based on canopy water vapor and CO2 fluxes to assess the response of canopy g to humidity. Using eddy-covariance flux measurements at three boreal forest sites in Canada, they critically examine the performance of the BWB and the Leuning models. The results show that the BWB model, which employs a linear relationship between g and relative humidity (hs), leads to large underestimates of g when the air is wet. The Leuning model, which employs a nonlinear function of water vapor pressure deficit (Ds), reduced this bias, but it still could not adequately capture the significant increase of g under the wet conditions. New models are proposed to improve the prediction of canopy g to humidity. The best performance was obtained by the model that employs a power function of Ds, followed by the model that employs a power function of relative humidity deficit (1 − hs). The results also indicate that models based on water vapor pressure deficit generally performed better than those based on relative humidity. This is consistent with the hypothesis that the stomatal aperture responds to leaf water loss because water vapor pressure deficit rather than relative humidity directly affects the transpiration rate of canopy leaves.
The Surface Circulation of the Caribbean Sea and the Gulf of Mexico as Inferred from Satellite Altimetry
Authors: Alvera-Azcárate Aida , Barth Alexander , Weisberg Robert H.
Published: September 2008

The surface circulation of the Caribbean Sea and Gulf of Mexico is studied using 13 years of satellite altimetry data. Variability in the Caribbean Sea is evident over several time scales. At the annual scale, sea surface height (SSH) varies mainly by a seasonal steric effect. Interannually, a longer cycle affects the SSH slope across the current and hence the intensity of the Caribbean Current. This cycle is found to be related to changes in the wind intensity, the wind stress curl, and El Niño–Southern Oscillation. At shorter time scales, eddies and meanders are observed in the Caribbean Current, and their propagation speed is explained by baroclinic instabilities under the combined effect of vertical shear and the β effect. Then the Loop Current (LC) is considered, focusing on the anticyclonic eddies shed by it and the intrusion of the LC into the Gulf of Mexico through time. Twelve of the 21 anticyclonic eddies observed to detach from the LC are shed from July to September, suggesting a seasonality in the timing of these events. Also, a relation is found between the intrusion of the LC into the Gulf of Mexico and the size of the eddies shed from it: larger intrusions trigger smaller eddies. A series of extreme LC intrusions into the Gulf of Mexico, when the LC is observed as far as 92°W, are described. The analyses herein suggest that the frequency of such events has increased in recent years, with only one event occurring in 1993 versus three from 2002 to 2006. Transport through the Straits of Florida appears to decrease during these extreme intrusions.
Northward Penetration of Antarctic Intermediate Water off Northwest Africa
Authors: Machín F. , Pelegrí J. L.
Published: September 2008

In this article, historical and climatological datasets are used to investigate the seasonal northward propagation of Antarctic Intermediate Waters (AAIW) along the eastern margin of the North Atlantic subtropical gyre. A cluster analysis for data north of 26°N shows the presence of a substantial number of hydrographic stations with AAIW characteristics that stretch northeast along the African slope. This water mass extends north during fall, as shown both through the comparison of actual and climatological data, and by applying a mixing analysis to normal-to-shore seasonal sections at both 28.5° and 32°N. The mixing analysis is further used with several fall cruises between 32° and 36°N, and shows that at these latitudes the core of AAIW propagates along the 27.5 isoneutral with contributions that reach as much as 50% at 32.5°N. An idealized Sverdrup-type model is used in combination with climatological hydrographic and wind data to examine what forces this eastern boundary propagation. It is found that column stretching, initiated in the tropical North Atlantic, is the dominant term in the vorticity balance of the AAIW stratum, capable of sustaining a winter–spring–summer northward transport of about 3–4 Sv (1 Sv ≡ 106 m3 s−1) that reaches as far north as the Canary Archipelago (28°N). In fall, this transport may continue beyond 28°N, sustained by a near-slope meridional stretching of this water stratum. AAIW probably fades away in the northeastern region as the result of several processes, specially enhanced double diffusion with surrounding waters and interaction with Mediterranean water lenses.
The South China Sea Throughflow Retrieved from Climatological Data*
Authors: Yaremchuk Max , McCreary Julian , Yu Zuojun , Furue Ryo
Published: September 2008

The salinity distribution in the South China Sea (SCS) has a pronounced subsurface maximum from 150–220 m throughout the year. This feature can only be maintained by the existence of a mean flow through the SCS, consisting of a net inflow of salty North Pacific tropical water through the Luzon Strait and outflow through the Mindoro, Karimata, and Taiwan Straits. Using an inverse modeling approach, the authors show that the magnitude and space–time variations of the SCS thermohaline structure, particularly for the salinity maximum, allow a quantitative estimate of the SCS throughflow and its distribution among the three outflow straits. Results from the inversion are compared with available observations and output from a 50-yr simulation of a highly resolved ocean general circulation model.

The annual-mean Luzon Strait transport is found to be 2.4 ± 0.6 Sv (Sv ≡ 106 m3 s−1). This inflow is balanced by the outflows from the Karimata (0.3 ± 0.5 Sv), Mindoro (1.5 ± 0.4), and Taiwan (0.6 ± 0.5 Sv) Straits. Results of the inversion suggest that the Karimata transport tends to be overestimated in numerical models. The Mindoro Strait provides the only passage from the SCS deeper than 100 m, and half of the SCS throughflow (1.2 ± 0.3 Sv) exits the basin below 100 m in the Mindoro Strait, a result that is consistent with a climatological run of a 0.1° global ocean general circulation model.
Transport in an Idealized Three-Gyre System with Application to the Adriatic Sea
Authors: Rypina Irina I. , Brown Michael G. , Koçak Huseyin
Published: September 2008

Motivated by observations of surface drifters in the Adriatic Sea, transport in a three-gyre system is studied with the aid of dynamical systems techniques. Particular attention is paid to the issue of intergyre transport. The velocity field is assumed to be two-dimensional and incompressible and composed of a steady three-gyre background flow on which a time-dependent perturbation is superimposed. Two systems of this type are considered: 1) an observationally motivated, analytically prescribed model consisting of a steady background on which a multiperiodic time-dependent perturbation is superimposed, and 2) an observationally based model of the Adriatic Sea consisting of the mean surface circulation derived from surface drifter trajectories on which a time-dependent altimetry-based perturbation velocity field is superimposed. It is shown that for a small perturbation to the steady three-gyre background, two of the gyres exchange no fluid with the third gyre. When the perturbation strength exceeds a certain threshold, transport between all three gyres occurs. This behavior is described theoretically, illustrated using the analytic model and shown to be consistent with the observationally based model of the Adriatic. The relevance of the work presented to more complicated multiple-gyre problems is discussed.
Observed Interannual Variability of the Florida Current: Wind Forcing and the North Atlantic Oscillation
Authors: DiNezio Pedro N. , Gramer Lewis J. , Johns William E. , Meinen Christopher S. , Baringer Molly O.
Published: September 2008

The role of wind stress curl (WSC) forcing in the observed interannual variability of the Florida Current (FC) transport is investigated. Evidence is provided for baroclinic adjustment as a physical mechanism linking interannual changes in WSC forcing and changes in the circulation of the North Atlantic subtropical gyre. A continuous monthly time series of FC transport is constructed using daily transports estimated from undersea telephone cables near 27°N in the Straits of Florida. This 25-yr-long time series is linearly regressed against interannual WSC variability derived from the NCEP–NCAR reanalysis. The results indicate that a substantial fraction of the FC transport variability at 3–12-yr periods is explained by low-frequency WSC variations. A lagged regression analysis is performed to explore hypothetical adjustment times of the wind-driven circulation. The estimated lag times are at least 2 times faster than those predicted by linear beta-plane planetary wave theory. Possible reasons for this discrepancy are discussed within the context of recent observational and theoretical developments. The results are then linked with earlier findings of a low-frequency anticorrelation between FC transport and the North Atlantic Oscillation (NAO) index, showing that this relationship could result from the positive (negative) WSC anomalies that develop between 20° and 30°N in the western North Atlantic during high (low) NAO phases. Ultimately, the observed role of wind forcing on the interannual variability of the FC could represent a benchmark for current efforts to monitor and predict the North Atlantic circulation.
Three-Dimensional Wind Retrieval: Application of MUSCAT to Dual-Doppler Lidar
Authors: Drechsel Susanne , Mayr Georg J. , Chong Michel , Weissmann Martin , Dörnbrack Andreas , Calhoun Ronald
Published: September 2008

During the field campaign of the Terrain-induced Rotor Experiment (T-REX) in the spring of 2006, Doppler lidar measurements were taken in the complex terrain of the Californian Owens Valley for six weeks. While fast three-dimensional (3D) wind analysis from measured radial wind components is well established for dual weather radars, only the feasibility was shown for dual-Doppler lidars. A computationally inexpensive, variational analysis method developed for multiple-Doppler radar measurements over complex terrain was applied. The general flow pattern of the 19 derived 3D wind fields is slightly smoothed in time and space because of lidar scan duration and analysis algorithm. The comparison of extracted wind profiles to profiles from radiosondes and wind profiler reveals differences of wind speed and direction of less than 1.1 m s−1 and 3°, on average, with standard deviations not exceeding 2.7 m s−1 and 27°, respectively. Standard velocity–azimuth display (VAD) retrieval method provided higher vertical resolution than the dual-Doppler retrieval, but no horizontal structure of the flow field. The authors suggest a simple way to obtain a good first guess for a dual-lidar scan strategy geared toward 3D wind retrieval that minimizes scan duration and maximizes spatial coverage.
Simulation of Significant Wave Height by Neural Networks and Its Application to Extreme Wave Analysis
Authors: Aminzadeh-Gohari A. , Bahai H. , Bazargan H.
Published: September 2008

The derivation of the long-term statistical distribution of significant wave heights (Hss) is discussed in this paper. The distribution parameters are estimated using artificial neural networks (ANNs) trained with the help of a simulated annealing algorithm and operated in an autoregressive mode. The ANNs were utilized in estimating the parameters of a conditional probability distribution related to a desired Hs given its preceding Hss, approximated by a proposed distribution called the hepta-parameter spline. The performance function during training was based on the likelihood function of the statistical method of maximum likelihood estimation (MLE). Given the observed dataset, the most probable weights and biases of the neural networks were determined in such a way that the performance function was optimized. The distribution could be used in the simulation and forecasting of Hss. This paper also presents an extreme wave analysis using the simulated Hss. The extreme analysis conducted in this study using the maxima method offers an alternative approach, avoiding the unrealistic hypothesis that annual Hss are identically distributed, as is conventionally assumed when using the Fisher–Tippet theorem.
Parameterization of PBL Processes in an Atmospheric General Circulation Model: Description and Preliminary Assessment
Authors: Konor Celal S. , Boezio Gabriel Cazes , Mechoso Carlos R. , Arakawa Akio
Published: September 2008

This paper presents the basic features of a newly developed planetary boundary layer (PBL) parameterization, and the performance assessment of a version of the University of California, Los Angeles (UCLA), Atmospheric General Circulation Model (AGCM) to which the parameterization is incorporated. The UCLA AGCM traditionally uses a framework in which a sigma-type vertical coordinate for the PBL shares a coordinate surface with the free atmosphere at the PBL top. This framework facilitates an explicit representation of processes concentrated near the PBL top, which is crucially important especially for predicting PBL clouds. In the new framework, multiple layers are introduced between the PBL top and earth’s surface, allowing for predictions of the vertical profiles of potential temperature, total water mixing ratio, and horizontal winds within the PBL. The vertically integrated “bulk” turbulent kinetic energy (TKE) is also predicted for the PBL. The PBL-top mass entrainment is determined through an equation including the effects of TKE and the radiative and evaporative cooling processes concentrated near the PBL top. The surface fluxes are determined from an aerodynamic formula in which the velocity scale depends both on the square root of TKE and the grid-scale PBL velocity at the lowermost model layer. The turbulent fluxes within the PBL are determined through an approach that includes the effects of both large convective and small diffusive eddies. AGCM simulations with the new formulation of PBL are analyzed with a focus on the seasonal and diurnal variations. The simulated seasonal cycle of stratocumulus over the eastern oceans is realistic, as are the diurnal cycles of the PBL depth and precipitation over land. The simulated fluxes of latent heat, momentum, and shortwave radiation at the ocean surface and baroclinic activity in the middle latitudes show significant improvements over the previous versions of the AGCM based on the single-layer PBL.
Multipeak Raindrop Size Distribution Observed by UHF/VHF Wind Profilers during the Passage of a Mesoscale Convective System
Authors: Radhakrishna B. , Rao T. Narayana
Published: September 2008

The Indian Mesosphere–Stratosphere–Troposphere radar (IMSTR), Lower Atmospheric Wind Profiler (LAWP), and Joss–Waldvogel (JW) disdrometer measurements during the passage of two distinctly different (in terms of total rain and rainfall rate) convective storms are utilized to understand the nature and origin of the multipeak raindrop size distribution (MRDSD). Important issues, such as the preferential stage and height at which bi- or multimodal rain distribution occurs in a mesoscale convective system (MCS) are addressed. For both of the storms, the MRDSD is observed during the transition period from convection to stratiform rain. The pattern and variation of the MRDSD during this period is strikingly similar in both of the storms. The MRDSD is first observed above the freezing level in the presence of heavy riming. The subsequent spectra have shown bimodal distribution below the freezing level, and the bimodality is attributed to the coexistence of ice and supercooled droplets. Interestingly, the bimodal distribution has not varied much with altitude when it is produced because of the coexistence of ice and supercooled droplets. The MRDSD is also observed at few range gates and for a short duration. Such a type of MRDSD is seen during the transition period between decaying and intensifying rain.
Communicating Social Identity
Authors: Hargie Owen , Dickson David , Mallett John , Stringer Maurice
Published: September 2008

This article examined communicative aspects of social identity theory in the context of the deeply divided community of Northern Ireland. Self-disclosure was selected for analysis, given its central role in the development of cross-group friendships and related reduction of negative bias towards the outgroup. In view of previous research on factors that mediate the decision to self-disclose to the outgroup, and using the Disclosure Decision Model as a guiding framework, the authors hypothesized that outgroup contact would be a key determinant of disclosure but that contact would be mediated by degree of trust and attraction for the outgroup, as well as by strength of ingroup identification. The findings supported these predictions. The results are discussed both in relation to the importance of communication facets of social identity theory and in light of wider policy implications for cross-group communication in Northern Ireland.
Daily symptom burden in end-stage chronic organ failure: a systematic review
Authors: Janssen DJA , Spruit MA , Wouters EFM , Schols JMGA
Published: September 2008

Chronic diseases are nowadays the major cause of morbidity and mortality worldwide. Patients with end-stage chronic organ failure may suffer daily from distressful physical and psychological symptoms. The objective of the present study is to systematically review studies that examined daily symptom prevalence in patients with end-stage chronic organ failure, with attention to those that included patients with either congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD) or chronic renal failure (CRF). Thirty-nine articles (8 CHF, 7 COPD, 2 CHF and COPD, 22 CRF) have been included. The included studies used various study designs. There was a wide range of daily symptom prevalence that may be due to the heterogeneity in methodology used. Nevertheless, findings suggest significant symptom burden in these patients. This review highlights the need for further prospective and longitudinal research on symptom prevalence in patients with end-stage CHF, COPD and CRF to facilitate the development of patient-centred palliative care programs.
Is emotional intelligence impaired in ecstasy-polydrug users?
Authors: Craig L. , Fisk JE , Montgomery C. , Murphy PN , Wareing M.
Published: September 2008

Previous findings report use of the drug ecstasy (MDMA) to be associated with lower emotional intelligence (EI), and compromised functioning in brain areas responsible for emotion. This study explored the relationship between ecstasy use, EI, mood and parenting styles. Questionnaire measures of drug use, lifestyle, parenting style and EI were obtained, with separate IQ measures for fluid intelligence (Ravens matrices) and pre-morbid intelligence [National Adult Reading Test (NART)]. Current mood measures were obtained from an adjective checklist. The sample comprised 78 ecstasy/polydrug users, 38 cannabis only users and 34 non-drug users. Drug use was categorised at three levels (non-user, cannabis-only user and ecstasy-polydrug user). Factorial ANOVA using drug use as an independent variable showed no significant group effects in EI. EI showed significant correlations with current mood that were positive for arousal and negative for both anxiety and depression. EI was also significantly and positively correlated with the perceived degree of parental control. Regression analyses showed that these relationships remained significant after controlling for differences in IQ, age, gender, and ecstasy use. Adverse mood effects specifically associated with ecstasy use were significantly related to lower EI, and were independent of IQ, age and gender. Higher EI was significantly associated with ecstasy-related precautions used when taking this drug. Contrary to earlier findings, ecstasy-polydrug users did not differ from non-users on EI. However, self-reported ecstasy-related mood disturbances were related to lower EI, with the compromising of orbitofrontal cortical functioning being possible here.
The µ-opioid receptor agonist remifentanil induces acute dysphoria irrespective of its analgesic properties
Authors: Wagner KJ , Valet M. , Kochs EF , Kriner M. , Tölle TR , Sprenger T.
Published: September 2008

µ-opioidergic agonists are believed to induce euphoria, whereas κagonists are thought to lead to dysphoria. Our study investigated mood effects of remifentanil, a µ-receptor opioid agonist, in healthy male volunteers. Moreover, we examined interactions between mood and pain. Three conditions were investigated in 21 volunteers: saline, 0.05 and 0.15 μg kg−1min− 1remifentanil. Each condition was investigated during non-painful heat and during painful heat stimulation. Mood was measured with the von Zerssen’s mood scale (Bf-S score) and pain intensity using a Visual Analogue Scale (VAS). High Bf-S scores are reflecting discontent and dysphoria. Changes were tested for significance using a linear mixed model approach. Remifentanil significantly increased Bf-S scores during painful heat (+91.4%), indicating a negative mood effect, although it reduced VAS scores of painful heat intensity (−49.0%). The type of sensory stimulation (non-painful versus painful) had no effect on mood. There was no interaction between remifentanil dose and type of stimulation. Our results provide evidence for negative mood effects of remifentanil. These effects occur with and without pain. Taken into account that remifentanil reduces pain, one could have expected analgesia-related amelioration of mood instead. In clinical practice, these remifentanil effects should be considered and a comedication might be advisable.
Olanzapine and breast-feeding: changes of plasma concentrations of olanzapine in a breast-fed infant over a period of 5 months
Authors: Whitworth A. , Stuppaeck C. , Yazdi K. , Kralovec K. , Geretsegger C. , Zernig G. , Aichhorn W.
Published: September 2008

We here report on a psychotic mother and her breast-fed infant who was treated with olanzapine. Consecutively olanzapine concentrations in the milk and plasma of the mother and in the infant were measured with tandem mass spectroscopy over a period of five month. The results show a relatively high plasma level in the infant aged four month, probably referring to an immature hepatic transformation system, especially CYP1A2. In the following four months plasma levels of olanzapine decreased to very low, even undetectable concentrations in the infant. The infant developed normally and showed no side effects during the treatment period.
Inhibition of THC-induced effects on the central nervous system and heart rate by a novel CB1 receptor antagonist AVE1625
Authors: Zuurman L. , Roy C. , Schoemaker RC , Amatsaleh A. , Guimaeres L. , Pinquier JL , Cohen AF , van Gerven JMA
Published: September 2008

CB1 antagonists such as AVE1625 are potentially useful in the treatment of obesity, smoking cessation and cognitive impairment. Proof of pharmacological action of AVE1625 in the brain can be given by antagonising the effects of delta-9-tetrahydrocannabinol (THC), a CB1/CB2 agonist. Inhibition of THC-induced effects by AVE1625 was observed on Visual Analogue Scales ‘alertness’, ‘feeling high’, ‘external perception’, ‘body sway’ and ‘heart rate’. Even the lowest dose of AVE1625 20 mg inhibited most of THC-induced effects. AVE1625 did not have any effect on psychological and behavioural parameters or heart rate by itself. After THC and AVE1625 administration, changes on electroencephalography were observed. This study shows a useful method for studying the effects of CB1 antagonists. AVE1625 penetrates the brain and antagonises THC-induced effects with doses at or above 20 mg.
Cannabidiol for the treatment of psychosis in Parkinson’s disease
Authors: Zuardi AW , Crippa Jas , Hallak JEC , Pinto JP , Chagas MHN , Rodrigues GGR , Dursun SM , Tumas V.
Published: September 2008

The management of psychosis in Parkinson’s disease (PD) has been considered a great challenge for clinicians and there is a need for new pharmacological intervention. Previously an antipsychotic and neuroprotective effect of Cannabidiol (CBD) has been suggested. Therefore, the aim of the present study was to directly evaluate for the first time, the efficacy, tolerability and safety of CBD on PD patients with psychotic symptoms. This was an open-label pilot study. Six consecutive outpatients (four men and two women) with the diagnosis of PD and who had psychosis for at least 3 months were selected for the study. All patients received CBD in flexible dose (started with an oral dose of 150 mg/day) for 4 weeks, in addition to their usual therapy. The psychotic symptoms evaluated by the Brief Psychiatric Rating Scale and the Parkinson Psychosis Questionnaire showed a significant decrease under CBD treatment. CBD did not worsen the motor function and decreased the total scores of the Unified Parkinson’s Disease Rating Scale. No adverse effect was observed during the treatment. These preliminary data suggest that CBD may be effective, safe and well tolerated for the treatment of the psychosis in PD.
Characteristic Complications after Autologous Chondrocyte Implantation for Cartilage Defects of the Knee Joint
Authors: Niemeyer Philipp , Pestka Jan M. , Kreuz Peter C. , Erggelet Christoph , Schmal Hagen , Suedkamp Norbert P. , Steinwachs Matthias
Published: September 2008

Background

Although autologous chondrocyte implantation (ACI) is a well-established therapy for the treatment of isolated cartilage defects of the knee joint, little is known about typical complications and their treatment after ACI.

Hypothesis

Unsatisfactory outcome after ACI is associated with technique-related typical complications.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 309 consecutive patients with 349 ACI procedures of the knee joint were analyzed. Three different ACI techniques were used: periosteum-covered ACI in 52 cases (14.9%), Chondrogide (Geistlich Biomaterials, Wolhusen, Switzerland) membrane-covered ACI in 215 cases (61.6%), and a 3-dimensional matrix-associated ACI (BioSeed-C, Biotissue Technologies, Freiburg, Germany) in 82 cases (23.5%). In 52 patients, revision surgery was performed for persistent clinical problems. These patients were analyzed for defect size and location, technique of ACI, and intraoperative findings during revision surgery. The mean time of follow-up for patients after ACI was 4.5 years (standard deviation, ±1.5).

Results

Four typical major complications were identified: hypertrophy of the transplant, disturbed fusion of the regenerative cartilage and the healthy surrounding cartilage, insufficient regenerative cartilage, and delamination. These diagnoses covered a total of 88.5% of the patients who underwent revision surgery. The overall complication rate was highest in the group of patients treated with periosteum-covered ACI ( P = .008). The incidence of symptomatic hypertrophy was 5.2% for all techniques and defect locations; the highest incidence was in patients treated with periosteum-covered ACI (15.4%) ( P = .001). The incidence of disturbed fusion was highest in the Chondrogide-covered ACI (3.7%) and the matrix-associated ACI group (4.8%). Concerning the incidence of complications by defect location, there was a tendency for increased complications in patellar defects ( P = .095). Within the patellar defects group, no correlation was found for the occurrence of delamination, insufficient regeneration, and disturbed fusion. As a statistical trend, an increased rate of hypertrophy was found for patellar defects ( P = .091).

Conclusion

A major proportion of complications after ACI can be summarized by 4 major diagnoses (symptomatic hypertrophy, disturbed fusion, delamination, and graft failure). Among those, the overall complication rate and incidence of hypertrophy of the transplant were higher for periosteum-covered ACI. Furthermore, an increased rate of symptomatic hypertrophy was found for patellar defects. Therapeutic concepts need to be developed to treat these typical complications of ACI.