Zhengyu Liu
The Ohio State University, Geography, Faculty Member
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Understanding the past significant changes of the East Asia Summer Monsoon (EASM) and Winter Monsoon (EAWM) is critical for improving the projections of future climate over East Asia. One key issue that has remained outstanding from the... more
Understanding the past significant changes of the East Asia Summer Monsoon (EASM) and Winter Monsoon (EAWM) is critical for improving the projections of future climate over East Asia. One key issue that has remained outstanding from the paleo-climatic records is whether the evolution of the EASM and EAWM are correlated. Here, using a set of long-term transient simulations of the climate evolution of the last 21,000 years, we show that the EASM and EAWM are positively correlated on the orbital timescale in response to the precessional forcing, but are anti-correlated on millennial timescales in response to North Atlantic melt water forcing. The relation between EASM and EAWM can differ dramatically for different timescales because of the different response mechanisms, highlighting the complex dynamics of the East Asian monsoon system and the challenges for future projection.
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The mitogenic effects of periodic mechanical stress on chondrocytes have been studied extensively but the mechanisms whereby chondrocytes sense and respond to periodic mechanical stress remain a matter of debate. We explored the signal... more
The mitogenic effects of periodic mechanical stress on chondrocytes have been studied extensively but the mechanisms whereby chondrocytes sense and respond to periodic mechanical stress remain a matter of debate. We explored the signal transduction pathways of chondrocyte proliferation and matrix synthesis under periodic mechanical stress. In particular, we sought to identify the role of the MEK1/2-ERK1/2 signaling pathway in chondrocyte proliferation and matrix synthesis following cyclic physiologic mechanical compression. Under periodic mechanical stress, both rat chondrocyte proliferation and matrix synthesis were significantly increased (P < 0.05) and were associated with increases in the phosphorylation of Src, PLCγ1, MEK1/2, and ERK1/2 (P < 0.05). Pretreatment with the MEK1/2-ERK1/2 selective inhibitor, PD98059, and shRNA targeted to ERK1/2 reduced periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis (P…
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During the last deglaciation, wetter conditions developed abruptly ~14,700 years ago in southeastern equatorial and northern Africa and continued into the Holocene. Explaining the abrupt onset and hemispheric coherence of this early... more
During the last deglaciation, wetter conditions developed abruptly ~14,700 years ago in southeastern equatorial and northern Africa and continued into the Holocene. Explaining the abrupt onset and hemispheric coherence of this early African Humid Period is challenging due to opposing seasonal insolation patterns. In this work, we use a transient simulation with a climate model that provides a mechanistic understanding of deglacial tropical African precipitation changes. Our results show that meltwater-induced reduction in the Atlantic meridional overturning circulation (AMOC) during the early deglaciation suppressed precipitation in both regions. Once the AMOC reestablished, wetter conditions developed north of the equator in response to high summer insolation and increasing greenhouse gas (GHG) concentrations, whereas wetter conditions south of the equator were a response primarily to the GHG increase.
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Records from South America show that modern ENSO (El Nino-Southern Oscillation) did not exist 7000 cal yr B.P. and has developed progressively since then. There has been little information available on oceanic conditions in the eastern... more
Records from South America show that modern ENSO (El Nino-Southern Oscillation) did not exist 7000 cal yr B.P. and has developed progressively since then. There has been little information available on oceanic conditions in the eastern equatorial Pacific (EEP) to constrain explanations for ENSO onset. We report quantitative observations on thermocline and mixed-layer conditions in the EEP during ENSO start up. We found important changes in both the thermocline and the mixed layer, indicating increased upwelling of cooler waters since 7000 cal yr B.P. This resulted from change in the source and/or properties of waters supplying the Equatorial Undercurrent, which feeds upwelling along the equator and the Peru margin. Modeling shows that ENSO is sensitive to subsurface conditions in the eastern equatorial Pacific and that the changes in the thermocline we observed were driven by extratropical processes, giving these a role in conditioning the development of ENSO. This is in contrast to...
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While there is very little known about the physiology and function of the CRF 2 subfamily of receptors, a substantial amount of preclinical and clinical data exists that suggests that CRF and its high-affinity receptor play a major role... more
While there is very little known about the physiology and function of the CRF 2 subfamily of receptors, a substantial amount of preclinical and clinical data exists that suggests that CRF and its high-affinity receptor play a major role in mediating various neurological and ...
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This study analyzes the response of global water vapor to global warming in a series of fully coupled climate model simulations. The authors find that a roughly 7% K−1 rate of increase of water vapor with global surface temperature is... more
This study analyzes the response of global water vapor to global warming in a series of fully coupled climate model simulations. The authors find that a roughly 7% K−1 rate of increase of water vapor with global surface temperature is robust only for rapid anthropogenic-like climate change. For slower warming that occurred naturally in the past, the Southern Ocean has time to equilibrate, producing a different pattern of surface warming, so that water vapor increases at only 4.2% K−1. This lower rate of increase of water vapor with warming is not due to relative humidity changes or differences in mean lower-tropospheric temperature. A temperature of over 80°C would be required in the Clausius–Clapeyron relationship to match the 4.2% K−1 rate of increase. Instead, the low rate of increase is due to spatially heterogeneous warming. During slower global warming, there is enhanced warming at southern high latitudes, and hence less warming in the tropics per kelvin of global surface temp...
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The feedback between global vegetation greenness and surface air temperature and precipitation is assessed using remote sensing observations of monthly fraction of photosynthetically active radiation (FPAR) for 1982 to 2000 with a 2.5°... more
The feedback between global vegetation greenness and surface air temperature and precipitation is assessed using remote sensing observations of monthly fraction of photosynthetically active radiation (FPAR) for 1982 to 2000 with a 2.5° grid resolution. Lead/lag correlations are used to infer vegetation–climate interactions. Furthermore, a statistical method is used to quantify the efficiency of vegetation feedback on climate in the observations. This feedback analysis provides a first quantitative assessment of global vegetation feedback on climate. In northern mid- and high latitudes, vegetation variability is found to be driven predominantly by temperature; in the meantime, vegetation also exerts a strong positive feedback on temperature with the feedback accounting for over 10%–25% of the total monthly temperature variance. The strongest positive feedback occurs in the boreal regions of southern Canada/northern United States, northern Europe, and southern Siberia, where the feedb...
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Rising levels of carbon dioxide since the preindustrial era have likely contributed to an observed warming of the global surface, and observations show global greening and an expansion of boreal forests. This study reproduces observed... more
Rising levels of carbon dioxide since the preindustrial era have likely contributed to an observed warming of the global surface, and observations show global greening and an expansion of boreal forests. This study reproduces observed climate and vegetation trends associated with rising CO2 using a fully coupled atmosphere–ocean–land surface GCM with dynamic vegetation and decomposes the effects into physiological and radiative components. The simulated warming trend, strongest at high latitudes, was dominated by the radiative effect, although the physiological effect of CO2 on vegetation (CO2 fertilization) contributed to significant wintertime warming over northern Europe and central and eastern Asia. The net global greening of the model was primarily due to the physiological effect of increasing CO2, while the radiative and physiological effects combined to produce a poleward expansion of the boreal forests. Observed and simulated trends in tree ring width are consistent with the...
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Research Interests: Membrane Proteins, Biological Chemistry, Signal Transduction, Biological Sciences, Saccharomyces cerevisiae, and 15 moreCercopithecus aethiops, Cell Differentiation, Brain, Humans, Animals, Alternative splicing, Pheochromocytoma, Neurons, CHEMICAL SCIENCES, Rats, Transfection, Alternative Splicing, Protein Binding, Asparagine, and Valine
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A coupled ocean‐atmosphere general circulation model is used to investigate climatic shift of El Nino in the Holocene. The model simulates a reduced ENSO intensity in the early and mid‐Holocene, in agreement with paleoclimate record. The... more
A coupled ocean‐atmosphere general circulation model is used to investigate climatic shift of El Nino in the Holocene. The model simulates a reduced ENSO intensity in the early and mid‐Holocene, in agreement with paleoclimate record. The ENSO reduction is proposed ...
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The effect of the gyre north-south width on the inertial recirculation has been studied using a non-eddy resolving QG model. It is found that for the traditional sinusoidal Ekman pumping profile with a fixed maximum interior transport and... more
The effect of the gyre north-south width on the inertial recirculation has been studied using a non-eddy resolving QG model. It is found that for the traditional sinusoidal Ekman pumping profile with a fixed maximum interior transport and fixed viscosity, a smaller north-south width will produce a stronger inertial recirculation, unless the north-south width of the gyre becomes comparable with
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Several studies have shown that the use of different calendars in paleoclimate simulations can cause artificial phase shifts on insolation forcing and climatic responses. However, these important calendar corrections are still often... more
Several studies have shown that the use of different calendars in paleoclimate simulations can cause artificial phase shifts on insolation forcing and climatic responses. However, these important calendar corrections are still often neglected. In this paper, the phase shifts at the precession band is quantitatively assessed by converting the model data of the transient GCM climate simulation of Kutzbach et
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First generation EGFR TKIs (gefitinib, erlotinib) provide significant clinical benefit for NSCLC cancer patients with oncogenic EGFR mutations. Ultimately, these patients disease progresses, often driven by a second-site mutation in the... more
First generation EGFR TKIs (gefitinib, erlotinib) provide significant clinical benefit for NSCLC cancer patients with oncogenic EGFR mutations. Ultimately, these patients disease progresses, often driven by a second-site mutation in the EGFR kinase domain (T790M). Another liability of the first generation drugs is severe adverse events driven by inhibition of WT EGFR. As such, our goal was to develop a highly potent irreversible inhibitor with the largest selectivity ratio between the drug-resistant double mutants (L858R/T790M, Del/T790M) and WT EGFR. A unique approach to develop covalent inhibitors, optimization of reversible binding affinity, served as a cornerstone of this effort. PF-06459988, was discovered as a novel, third generation irreversible inhibitor, which demonstrates (i) high potency and specificity to the T790M-containing double mutant EGFRs, (ii) minimal intrinsic chemical reactivity of the electrophilic warhead, (iii) greatly reduced proteome reactivity relative to...
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Most previous studies have proven the local negative heat flux feedback (the surface heat flux response to SST anomalies) in the midlatitude areas. However, it is uncertain whether a nonlocal heat flux feedback can be observed. In this... more
Most previous studies have proven the local negative heat flux feedback (the surface heat flux response to SST anomalies) in the midlatitude areas. However, it is uncertain whether a nonlocal heat flux feedback can be observed. In this paper, the generalized equilibrium feedback assessment (GEFA) method is employed to examine the full surface turbulent heat flux response to SST in the North Atlantic Ocean using NCEP–NCAR reanalysis data. The results not only confirm the dominant local negative feedback, but also indicate a robust nonlocal positive feedback of the Gulf Stream Extension (GSE) SST to the downstream heat flux in the subpolar region. This nonlocal feedback presents a strong seasonality, with response magnitudes of [Formula: see text] in winter and [Formula: see text] in summer. Further study indicates that the nonlocal effect is initiated by the adjustments of the downstream surface wind to the GSE SST anomalies.
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The evolution of decadal subduction temperature anomalies in the subtropical North Pacific is studied using a simple and a complex ocean model. It is found that the amplitude of the temperature anomaly decays faster than a passive tracer... more
The evolution of decadal subduction temperature anomalies in the subtropical North Pacific is studied using a simple and a complex ocean model. It is found that the amplitude of the temperature anomaly decays faster than a passive tracer by about 30%-50%. The faster decay is caused by the divergence of group velocity of the subduction planetary wave, which is contributed to, significantly, by the divergent Sverdrup flow in the subtropical gyre. The temperature anomaly also seems to propagate southward slower than the passive tracer, or mean ventilation flow. This occurs because the mean potential vorticity gradient in the ventilated zone is directed eastward; the associated general beta effect produces a northward propagation for the temperature anomaly, partially canceling the southward advection by the ventilation flow.
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ABSTRACT This study investigates the direct impact of El Niño in the tropical Pacific on the East Asian summer precipitation . Generalized equilibrium feedback assessment is used to isolate this direct impact from interrelated ocean... more
ABSTRACT This study investigates the direct impact of El Niño in the tropical Pacific on the East Asian summer precipitation . Generalized equilibrium feedback assessment is used to isolate this direct impact from interrelated ocean forcings in the observations. Results indicate that the El Niño can directly influence the summer precipitation in East China significantly. The precipitation response presents a tri-pole pattern, with anomalous wet in the Southeast and the Northeast China and anomalous dry in the northern China. Amplitude of the precipitation response is around 20 % of the total precipitation for 1 °C El Niño forcing in most area of the East China, with maximal response up to 30 %/°C. The tri-pole precipitation response is attributed to an El Niño-induced cyclonic anomaly in the Northeast Asia and an anticyclonic anomaly in the western North Pacific (WNP). The anomalous cyclone deepens the East Asian trough southwestward, favoring an air ascending in front of the trough in the Southeast and the Northeast China, and an air descending at the rear of the trough in the northern China. The anomalous anticyclone in the WNP strengthens the WNP Subtropical High northeastward, providing adequate water vapor to the Southeast China. The anomalous cyclone and anomalous anticyclone work together to generate the tri-pole precipitation response pattern in the East China. Further investigation suggests that these two key anomalous circulations are part of a northwestward propagating Rossby wave, which is excited by the El Niño warming-induced convection over the subtropical west-central Pacific. This study can serve as a reference for the prediction of the East Asian precipitation in both the developing and decaying summer of El Niño.
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ABSTRACT The dynamics of glacialeinterglacial monsoon variability can be attributed to orbitally induced changes in summer insolation and internal boundary conditions. However, the relative impacts of astronomical and internal factors on... more
ABSTRACT The dynamics of glacialeinterglacial monsoon variability can be attributed to orbitally induced changes in summer insolation and internal boundary conditions. However, the relative impacts of astronomical and internal factors on East Asian summer monsoon variability remain controversial. Here we combine proxy data and model results to evaluate the response of East Asian summer monsoon change to these forcings. d13C of loess carbonate, a sensitive summer monsoon proxy from the western Chinese Loess Plateau, demonstrates coexistence of distinct 100-, 41- and 23-ka periods, in contrast to precession-dominated speleothem d18O records in South China. Model results indicate that insolation, ice and CO2 have distinct impacts on summer precipitation changes in East Asia, whereas their relative impacts are spatially different, with a relatively stronger insolation effect in south China and a more dominant ice/CO2 influence in north China. Combined proxy data and model results indicate that East Asian summer monsoon variability was induced by integrated effects of summer insolation and changing boundary conditions (e.g., ice sheets and CO2 concentration). Our proxy-model comparison further suggests that gradual weakening of the summer monsoon related to slowly decreasing summer insolation at astronomical timescales will be likely overwhelmed by the projected ongoing anthropogenic CO2 emissions.
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Genetic diversity level ofCathaya argyrophylla was confirmed by random amplified polymorphic DNA (RAPD) markers. Seventy five samples (individuals), collected from Hunan and Sichuan provinces of China were used in the study. 21 10-mer... more
Genetic diversity level ofCathaya argyrophylla was confirmed by random amplified polymorphic DNA (RAPD) markers. Seventy five samples (individuals), collected from Hunan and Sichuan provinces of China were used in the study. 21 10-mer oligonucleotide primers detected 106 sites, and 34 (32%) of them were polymorphic. The level of genetic variation in C.argyrophylla was lower than those of other conifers, and was considered to be associated with the complexity of habitats. The percentages of polymorphic sites (PPS) in the Hunan and Sichuan populations were 18% and 25% respectively. 7.99% of genetic variation existed between the two populations; this value was higher than the mean value (6.8%) among populations in conifers displayed by allozyme. Some subpopulations ofC. argyrophylla were greatly differentiated because of site mutation and genetic drift. The highest value of genetic difference between subpopulations amounted to 16. 23%. In addition, a concept of diversity coefficient (D...
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... 91191 Gif sur Yvette cedex France CHRIS D. HEWITT (chris.hewitt@metoffice.com) Hadley Centre for Climate Prediction and Research Met Office FitzRoy Road, Exceter Devon, EX1 3BP UK AKIO KITOH (kitoh@mri-jma.go ...