A new earth system climate model of intermediate complexity has been developed and its climatology compared to observations. The UVic Earth System Climate Model consists of a three-dimensional ocean ...general circulation model coupled to a thermodynamic/dynamic sea-ice model, an energy-moisture balance atmospheric model with dynamical feedbacks, and a thermomechanical land-ice model. In order to keep the model computationally efficient a reduced complexity atmosphere model is used. Atmospheric heat and freshwater transports are parametrized through Fickian diffusion, and precipitation is assumed to occur when the relative humidity is greater than 85%. Moisture transport can also be accomplished through advection if desired. Precipitation over land is assumed to return instantaneously to the ocean via one of 33 observed river drainage basins. Ice and snow albedo feedbacks are included in the coupled model by locally increasing the prescribed latitudinal profile of the planetary albedo. The atmospheric model includes a parametrization of water vapour/planetary longwave feedbacks, although the radiative forcing associated with changes in atmospheric CO
2
is prescribed as a modification of the planetary longwave radiative flux. A specified lapse rate is used to reduce the surface temperature over land where there is topography. The model uses prescribed present-day winds in its climatology, although a dynamical wind feedback is included which exploits a latitudinally-varying empirical relationship between atmospheric surface temperature and density. The ocean component of the coupled model is based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model 2.2, with a global resolution of 3.6° (zonal) by 1.8° (meridional) and 19 vertical levels, and includes an option for brine-rejection parametrization. The sea-ice component incorporates an elastic-viscous-plastic rheology to represent sea-ice dynamics and various options for the representation of sea-ice thermodynamics and thickness distribution. The systematic comparison of the coupled model with observations reveals good agreement, especially when moisture transport is accomplished through advection.
Global warming simulations conducted using the model to explore the role of moisture advection reveal a climate sensitivity of 3.0°C for a doubling of CO
2
, in line with other more comprehensive coupled models. Moisture advection, together with the wind feedback, leads to a transient simulation in which the meridional overturning in the North Atlantic initially weakens, but is eventually re-established to its initial strength once the radiative forcing is held fixed, as found in many coupled atmosphere General Circulation Models (GCMs). This is in contrast to experiments in which moisture transport is accomplished through diffusion whereby the overturning is reestablished to a strength that is greater than its initial condition.
When applied to the climate of the Last Glacial Maximum (LGM), the model obtains tropical cooling (30°N-30°S), relative to the present, of about 2.1°C over the ocean and 3.6°C over the land. These are generally cooler than CLIMAP estimates, but not as cool as some other reconstructions. This moderate cooling is consistent with alkenone reconstructions and a low to medium climate sensitivity to perturbations in radiative forcing. An amplification of the cooling occurs in the North Atlantic due to the weakening of North Atlantic Deep Water formation. Concurrent with this weakening is a shallowing of, and a more northward penetration of, Antarctic Bottom Water.
Climate models are usually evaluated by spinning them up under perpetual present-day forcing and comparing the model results with present-day observations. Implicit in this approach is the assumption that the present-day observations are in equilibrium with the present-day radiative forcing. The comparison of a long transient integration (starting at 6 KBP), forced by changing radiative forcing (solar, CO
2
, orbital), with an equilibrium integration reveals substantial differences. Relative to the climatology from the present-day equilibrium integration, the global mean surface air and sea surface temperatures (SSTs) are 0.74°C and 0.55°C colder, respectively. Deep ocean temperatures are substantially cooler and southern hemisphere sea-ice cover is 22% greater, although the North Atlantic conveyor remains remarkably stable in all cases. The differences are due to the long timescale memory of the deep ocean to climatic conditions which prevailed throughout the late Holocene. It is also demonstrated that a global warming simulation that starts from an equilibrium present-day climate (cold start) underestimates the global temperature increase at 2100 by 13% when compared to a transient simulation, under historical solar, CO
2
and orbital forcing, that is also extended out to 2100. This is larger (13% compared to 9.8%) than the difference from an analogous transient experiment which does not include historical changes in solar forcing. These results suggest that those groups that do not account for solar forcing changes over the twentieth century may slightly underestimate (∼3% in our model) the projected warming by the year 2100.
Background We evaluated the current results and the predictors of in-hospital complications for a pericardiectomy procedure for constrictive pericarditis in Japan. Methods A total of 346 patients who ...underwent isolated pericardiectomy for constrictive pericarditis nationwide between 2008 and 2012 were identified from the Japan Adult Cardiovascular Surgery Database. Results The patients were a mean age of 65.7 ± 11.7 years. The operative approach was through a median sternotomy in 90% of the patients. Cardiopulmonary bypass was used in 28.9%. The operative mortality rate was 10.0%, and the composite operative mortality or major morbidity (stroke, reoperation for bleeding, need for mechanical ventilation for more than 24 hours postoperatively due to respiratory failure, renal failure with newly required dialysis or mediastinitis) was 15.0%. Logistic regression analysis revealed that the predictive factors for composite operative mortality or major morbidity were preoperative chronic lung disease (odds ratio OR, 4.75; p < 0.001), New York Heart Association functional class IV (OR, 3.85; p < 0.001), previous cardiac operation (OR, 2.68; p = .006), preoperative renal failure (OR, 2.62; p = .014), and cardiopulmonary bypass during the operation (OR, 2.46; p = .015). The frequency of using cardiopulmonary bypass was 2.9% in the patients treated through a left thoracotomy approach vs 31.8% in the patients treated through a median sternotomy approach ( p < 0.0001). Conclusions Pericardiectomy is associated with high morbidity and mortality rates. Careful consideration should be given to these risk factors in the process of patient selection and perioperative management.
The response of the climate system to natural, external forcing during the Maunder Minimum (ca. A.D. 1645–1715) is investigated using a comprehensive climate model. An ensemble of six transient ...simulations is produced in order to examine the relative importance of externally forced and internally generated variability. The simulated annual Northern Hemisphere and zonal-mean near-surface air temperature agree well with proxy-based reconstructions on decadal time scales. A mean cooling signal during the Maunder Minimum is masked by the internal unforced variability in some regions such as Alaska, Greenland, and northern Europe. In general, temperature exhibits a better signal-to-noise ratio than precipitation. Mean salinity changes are found in basin averages. The model also shows clear response patterns to volcanic eruptions. In particular, volcanic forcing is projected onto the winter North Atlantic Oscillation index following the eruptions. It is demonstrated that the significant spread of ensemble members is possible even on multidecadal time scales, which has an important implication in coordinating comparisons between model simulations and regional reconstructions.
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Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To study glacial termination and related feedback mechanisms, a continental ice dynamics model is globally and asynchronously coupled to a physical climate (atmosphere-ocean-sea ice) model. The model ...performs well under present-day, 11kaBP (thousand years before present) and 21kaBP perpetual forcing. To address the ice-sheet response under the effects of both perpetual orbital and CO^sub 2^ forcing, sensitivity experiments are conducted with two different orbital configurations (11kaBP and 21kaBP) and two different atmospheric CO^sub 2^ concentrations (200ppmv and 280ppmv). This study reveals that, although both orbital and CO^sub 2^ forcing have an impact on ice-sheet maintenance and deglacial processes, and although neither acting alone is sufficient to lead to complete deglaciation, orbital forcing seems to be more important. The CO^sub 2^ forcing has a large impact on climate, not uniformly or zonally over the globe, but concentrated over the continents adjacent to the North Atlantic. The effect of increased CO^sub 2^ (from 200ppmv to 280ppmv) on surface air temperature has its peak there in winter associated with a reduction in sea-ice extent in the northern North Atlantic. These changes are accompanied by an enhancement in the intensity of the meridional overturning and poleward ocean heat transport in the North Atlantic. On the other hand, the effect of orbital forcing (from 21kaBP to 11kaBP) has its peak in summer. Since the summer temperature, rather than winter temperature, is found to be dominant for the ice-sheet mass balance, orbital forcing has a larger effect than CO^sub 2^ forcing in deglaciation. Warm winter sea surface temperature arising from increased CO^sub 2^ during the deglaciation contributes to ice-sheet nourishment (negative feedback for ice-sheet retreat) through slightly enhanced precipitation. However, the precipitation effect is totally overwhelmed by the temperature effect. Our results suggest that the last deglaciation was initiated through increasing summer insolation with CO^sub 2^ providing a powerful feedback.PUBLICATION ABSTRACT
In this exploratory comparative study of Toyota/GM and Canon/Xerox, the author purports to explain why the 10‐year performance of Toyota and Canon, despite their traditional Japanese primacy on job ...security, large board size and absence of non‐executive directors, is superior to that of their US rivals. The author compares the key stakeholder and the board structure as well as corporate values, culture and strategy of the sample firms and concludes that higher performance is possible without resorting to US‐style corporate governance, and proposes that corporate values, culture and strategy are equally vital ingredients of corporate success.
The aim of the study was to determine whether past exposure to hepatitis B virus (HBV) influences the risk of the development of hepatocellular carcinoma (HCC) in Japanese patients with chronic liver ...disease (CLD). We conducted a hospital-based case-control study of 141 HCC patients with CLD and 151 controls with CLD but without HCC. Past exposure to HBV was assessed by antibody to hepatitis B core antigen (anti-HBc) positivity. Ninety-two patients (65%) with HCC were anti-HBc positive compared with 65 patients (43%) with CLD alone (P < 0.01). A multivariate analysis using logistic regression modelling revealed that anti-HBc positivity significantly increased the risk of the development of HCC odds ratio (OR) 2.0, P = 0.01. In the anti-HBc-positive patients, a significantly increased risk of HCC was seen among the patients positive for anti-HBc alone (OR, 2.6; P < 0.01). However, a significant OR was not obtained among the patients with a transient HBV infection implied by positivity for both antibody to hepatitis B surface antigen and anti-HBc (OR, 1.5; P = 0.48). These results indicate that past exposure to HBV is a risk factor for HCC in Japanese CLD patients, especially when they have no serological evidence of immunity to HBV.
Gamma-ray observations from HINOTORI satellite and possible neutron observations from the Tokyo neutron monitor are reviewed. Time histories of gamma-ray and X-ray emissions for both typical ...impulsive and gradual flares are discussed in connection with the particle acceleration time. The gamma-ray spectral hardening observed around 400 keV is explained from superimposition of two different electron bremsstrahlung spectra. Proton-energy spectra derived from the gamma-ray observations are compared with the solar energetic particle spectra in interplanetary space. The weak correlation between the gamma-ray fluence and the proton flux is discussed in connection with the particle trapping and escaping in the flare region. The limb darkening of the 2.22 MeV line resulting from neutron-proton capture is interpreted in terms of the attenuation by the Compton scattering in the photosphere. Possible solar neutron events recorded by the Tokyo neutron monitor are presented and the correlation between the gamma-ray fluence and the neutron fluence are described.
Introduction:. Patients with pulmonary tuberculosis (TB) sometimes show persistent severe inflammation for more than 1 month, even if TB treatment is effective. Although this inflammation can be ...improved through continuous antituberculous therapy, the risk factors for persistent inflammation remain unclear. Therefore, we sought to study the characteristics of patients with persistent severe inflammation. Materials and methods:. We retrospectively analyzed 147 hospitalized adult patients with C-reactive protein (CRP) levels of 5 mg/dL or more on admission to Fukujuji Hospital from April 2019 to March 2021. The patients were divided into 2 groups: 40 patients (27.2%) had CRP levels of 5 mg/dL or more at 4 weeks after admission (persistent inflammation group), and 107 patients (72.8%) had CRP levels that fell below 5 mg/dL within 4 weeks of admission (improved inflammation group). Results:. The median CRP level on admission in the persistent inflammation group was 10.8 mg/dL (interquartile range 9.1–14.5), which was higher than that in the improved inflammation group (median 8.2 mg/dL 6.5–12.1, P = .002). Patients in the persistent inflammation group had a higher prevalence of large cavities, defined as cavities ≥4 cm in diameter, on chest computed tomography (CT) (n = 20 50.0% vs n = 12 11.2%, P < .001). Discussion and conclusions:. This study showed that 27.2% of patients who had high or moderate inflammation on admission did not achieve low CRP levels within 4 weeks after admission. Risk factors for persistent severe inflammation in patients with TB were presence of a large cavity (cavity diameter ≥4 cm) on chest CT and a high CRP level on admission. Therefore, in a patient with a large cavity on chest CT and/or CRP ≥9.0 mg/dL on admission, long-term inflammation may occur despite antituberculous therapy if other diseases are ruled out.
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