The Response of Parameterized Orographic Gravity Waves to Rapid Warming over the Tibetan Plateau

Using the ERA-Interim reanalysis during 1979–2017, this work for the first time investigates the climatology and long-term trend of orographic gravity waves (OGWs) in the Tibetan Plateau (TP). The linkage between the trends of OGWs and the rapid warming over the TP is also studied. Climatologically, the most prominent surface wave momentum flux (SWMF) of OGWs occurs in the western and southeastern TP, while it is weak in the central TP. The SWMF is stronger in winter and spring than in autumn and summer. Overall, the mean SWMF over the TP experienced a weak decreasing trend. The decrease of SWMF mainly took place in the western and southeastern TP in spring. However, increasing trends were found in the central TP in winter. Changes of SWMF are mainly caused by the changes of horizontal wind near the surface, while buoyancy frequency and air density play a minor role. In response to the inhomogeneous warming over the TP, the surface winds were adjusted through thermal wind balance. In spring (winter), the most remarkable warming occurred in the northern (southern) TP, which reduced (enhanced) the meridional temperature gradient across the plateau, and thus led to a deceleration (acceleration) of the horizontal wind.

Download Full-text

Occurrence of L1014F and L1014S mutations in insecticide resistant Culex quinquefasciatus from filariasis endemic districts of West Bengal, India

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0010000 ◽

2022 ◽

Vol 16 (1) ◽

pp. e0010000

Author(s):

Priyanka Rai ◽

Dhiraj Saha

Keyword(s):

Culex Quinquefasciatus ◽

West Bengal ◽

Economic Status ◽

Minor Role ◽

Resistance Development ◽

Vector Population ◽

A Minor ◽

First Time

Introduction Lymphatic filariasis causes long term morbidity and hampers the socio-economic status. Apart from the available treatments and medication, control of vector population Culex quinquefasciatus Say through the use of chemical insecticides is a widely applied strategy. However, the unrestrained application of these insecticides over many decades has led to resistance development in the vectors. Methods In order to determine the insecticide susceptibility/resistance status of Cx. quinquefasciatus from two filariasis endemic districts of West Bengal, India, wild mosquito populations were collected and assayed against six different insecticides and presence of L1014F; L1014S kdr mutations in the voltage-gated sodium channel gene was also screened along with the use of synergists to evaluate the role of major detoxifying enzymes in resistance development. Results The collected mosquito populations showed severe resistance to insecticides and the two synergists used–PBO (piperonyl butoxide) and TPP (triphenyl phosphate), were unable to restore the susceptibility status of the vector thereupon pointing towards a minor role of metabolic enzymes. kdr mutations were present in the studied populations in varying percent with higher L1014F frequency indicating its association with the observed resistance to pyrethroids and DDT. This study reports L1014S mutation in Cx. quinquefasciatus for the first time.

Download Full-text

Natural Competence Is a Major Mechanism for Horizontal DNA Transfer in the Oral Pathogen Porphyromonas gingivalis

mBio ◽

10.1128/mbio.00231-11 ◽

2012 ◽

Vol 3 (1) ◽

Cited By ~ 40

Author(s):

Gena D. Tribble ◽

Todd W. Rigney ◽

Doan-Hieu V. Dao ◽

Cindy T. Wong ◽

Jennifer E. Kerr ◽

...

Keyword(s):

Porphyromonas Gingivalis ◽

Dna Transfer ◽

Extracellular Dna ◽

Minor Role ◽

Chromosomal Dna ◽

Natural Competence ◽

Content Type ◽

A Minor ◽

First Time

ABSTRACTPorphyromonas gingivalisis a Gram-negative anaerobe that resides exclusively in the human oral cavity. Long-term colonization byP. gingivalisrequires the bacteria to evade host immune responses while adapting to the changing host physiology and alterations in the composition of the oral microflora. The genetic diversity ofP. gingivalisappears to reflect the variability of its habitat; however, little is known about the molecular mechanisms generating this diversity. Previously, our research group established that chromosomal DNA transfer occurs betweenP. gingivalisstrains. In this study, we examine the role of putative DNA transfer genes in conjugation and transformation and demonstrate that natural competence mediated bycomFis the dominant form of chromosomal DNA transfer, with transfer by a conjugation-like mechanism playing a minor role. Our results reveal that natural competence mechanisms are present in multiple strains ofP. gingivalis, and DNA uptake is not sensitive to DNA source or modification status. Furthermore, extracellular DNA was observed for the first time inP. gingivalisbiofilms and is predicted to be the major DNA source for horizontal transfer and allelic exchange between strains. We propose that exchange of DNA in plaque biofilms by a transformation-like process is of major ecological importance in the survival and persistence ofP. gingivalisin the challenging oral environment.IMPORTANCEP. gingivaliscolonizes the oral cavities of humans worldwide. The long-term persistence of these bacteria can lead to the development of chronic periodontitis and host morbidity associated with tooth loss.P. gingivalisis a genetically diverse species, and this variability is believed to contribute to its successful colonization and survival in diverse human hosts, as well as evasion of host immune defenses and immunization strategies. We establish here that natural competence is the major driving force behindP. gingivalisDNA exchange and that conjugative DNA transfer plays a minor role. Furthermore, we reveal for the first time the presence of extracellular DNA inP. gingivalisbiofilms, which is most likely the source of DNA exchanged between strains within dental plaque. These studies expand our understanding of the mechanisms used by this important member of the human oral flora to transition its relationship with the host from a commensal to a pathogenic relationship.

Download Full-text

Trends of Sampling Error in Surface Air Temperature on the Tibetan Plateau during Recent Decades

Advances in Meteorology ◽

10.1155/2019/3160327 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10

Author(s):

Wei Hua ◽

Tianci Huang ◽

Zouxin Lin ◽

Lihua Zhu ◽

Xin Wang ◽

...

Keyword(s):

Tibetan Plateau ◽

Air Temperature ◽

Sampling Error ◽

Surface Air Temperature ◽

The Tibetan Plateau ◽

Statistical Inferences ◽

Increasing Trends ◽

Climate Studies ◽

Monthly Variations

Understanding errors in surface air temperature (SAT) data and related uncertainties is crucial for climate studies because of their impact on the accuracy of statistical inferences in scientific conclusions. In recent decades, considerable research has focused on the trends and evolution of SAT on the Tibetan Plateau (TP). However, assessment of the uncertainties in SAT change on the TP has not been done adequately, which is of considerable importance for climate research. Using station-observed SAT data from the TP, this study estimates long-term variations and trends of sampling error variances in gridded monthly SAT data over recent decades. Results revealed large sampling error variances in northern and western parts of the TP but small variances in eastern, southern, and central areas. The sampling error variances also exhibited strong monthly variations with maximum errors in winter and minimum values in summer. Furthermore, spatial distributions of the trends of seasonal and annual mean sampling error variances were found distributed unevenly with decreasing trends found mainly in central and southern parts of the TP and increasing trends in northeastern, southeastern, and northwestern areas. Additionally, differences were also found in the trends of seasonal and annual mean sampling error variances on various timescales.

Download Full-text

On the Momentum Flux of Vertically-Propagating Orographic Gravity Waves Excited in Nonhydrostatic Flow over Three-dimensional Orography

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-20-0370.1 ◽

2021 ◽

Author(s):

Xin Xu ◽

Runqiu Li ◽

Miguel A. C. Teixeira ◽

Yixiong Lu

Keyword(s):

Gravity Waves ◽

Wind Direction ◽

Momentum Flux ◽

Wave Spectrum ◽

Three Dimensional ◽

Horizontal Wind ◽

Buoyancy Frequency ◽

Minor Role ◽

Linear Wave ◽

Vertically Propagating

AbstractThis work studies nonhydrostatic effects (NHE) on the momentum flux of orographic gravity waves (OGWs) forced by isolated three-dimensional orography. Based on linear wave theory, an asymptotic expression for low horizonal Froude number ( where (U, V) is the mean horizontal wind, γ and a are the orography anisotropy and half-width and N is the buoyancy frequency) is derived for the gravity wave momentum flux (GWMF) of vertically-propagating waves. According to this asymptotic solution, which is quite accurate for any value of Fr, NHE can be divided into two terms (NHE1 and NHE2). The first term contains the high-frequency parts of the wave spectrum that are often mistaken as hydrostatic waves, and only depends on Fr. The second term arises from the difference between the dispersion relationships of hydrostatic and nonhydrostatic OGWs. Having an additional dependency on the horizontal wind direction and orography anisotropy, this term can change the GWMF direction. Examination of NHE for OGWs forced by both circular and elliptical orography reveals that the GWMF is reduced as Fr increases, at a faster rate than for two-dimensional OGWs forced by a ridge. At low Fr, the GWMF reduction is mostly attributed to the NHE2 term, whereas the NHE1 term starts to dominate above about Fr = 0.4. The behavior of NHE is mainly determined by Fr, while horizontal wind direction and orography anisotropy play a minor role. Implications of the asymptotic GWMF expression for the parameterization of nonhydrostatic OGWs in high-resolution and/or variable-resolution models are discussed.

Download Full-text

Atmospheric Thermal and Dynamic Vertical Structures of Summer Hourly Precipitation in Jiulong of the Tibetan Plateau

Atmosphere ◽

10.3390/atmos12040505 ◽

2021 ◽

Vol 12 (4) ◽

pp. 505

Author(s):

Yonglan Tang ◽

Guirong Xu ◽

Rong Wan ◽

Xiaofang Wang ◽

Junchao Wang ◽

...

Keyword(s):

Wind Speed ◽

Tibetan Plateau ◽

Precipitation Amount ◽

Summer Precipitation ◽

The Tibetan Plateau ◽

Hourly Precipitation ◽

Air Convection ◽

Precipitation Variation ◽

Long Term Observation

It is an important to study atmospheric thermal and dynamic vertical structures over the Tibetan Plateau (TP) and their impact on precipitation by using long-term observation at representative stations. This study exhibits the observational facts of summer precipitation variation on subdiurnal scale and its atmospheric thermal and dynamic vertical structures over the TP with hourly precipitation and intensive soundings in Jiulong during 2013–2020. It is found that precipitation amount and frequency are low in the daytime and high in the nighttime, and hourly precipitation greater than 1 mm mostly occurs at nighttime. Weak precipitation during the daytime may be caused by air advection, and strong precipitation at nighttime may be closely related with air convection. Both humidity and wind speed profiles show obvious fluctuation when precipitation occurs, and the greater the precipitation intensity, the larger the fluctuation. Moreover, the fluctuation of wind speed is small in the morning, large at noon and largest at night, presenting a similar diurnal cycle to that of convective activity over the TP, which is conductive to nighttime precipitation. Additionally, the inverse layer is accompanied by the inverse humidity layer, and wind speed presents multi-peaks distribution in its vertical structure. Both of these are closely related with the underlying surface and topography of Jiulong. More studies on physical mechanism and numerical simulation are necessary for better understanding the atmospheric phenomenon over the TP.

Download Full-text

Atmospheric Water Vapor Budget and its Long-term Trend over the Tibetan Plateau

10.1002/essoar.10503906.1 ◽

2020 ◽

Author(s):

Hongru Yan ◽

Jianping Huang ◽

Yongli He ◽

Yuzhi Liu ◽

Tianhe Wang ◽

...

Keyword(s):

Water Vapor ◽

Tibetan Plateau ◽

Atmospheric Water Vapor ◽

The Tibetan Plateau ◽

Atmospheric Water ◽

Term Trend ◽

Long Term Trend ◽

Water Vapor Budget

Download Full-text

NgCAM and VAMP2 Reveal that Direct Delivery and Dendritic Degradation Maintain Axonal Polarity

Molecular Biology of the Cell ◽

10.1091/mbc.e21-08-0425 ◽

2021 ◽

Author(s):

Alec T. Nabb ◽

Marvin Bentley

Keyword(s):

Membrane Proteins ◽

Molecular Mechanisms ◽

Minor Role ◽

Axonal Membrane ◽

Quantitative Analyses ◽

Direct Delivery ◽

Novel Strategy ◽

Extreme Scale ◽

A Minor

Neurons are polarized cells of extreme scale and compartmentalization. To fulfill their role in electrochemical signaling, axons must maintain a specific complement of membrane proteins. Despite being subject of considerable attention, the trafficking pathway of axonal membrane proteins is not well understood. Two pathways, direct delivery and transcytosis, have been proposed. Previous studies reached contradictory conclusions about which of these mediates delivery of axonal membrane proteins to their destination, in part because they evaluated long-term distribution changes and not vesicle transport. We developed a novel strategy to selectively label vesicles in different trafficking pathways and determined the trafficking of two canonical axonal membrane proteins, NgCAM and VAMP2. Results from detailed quantitative analyses of transporting vesicles differed substantially from previous studies and found that axonal membrane proteins overwhelmingly undergo direct delivery. Transcytosis plays only a minor role in axonal delivery of these proteins. In addition, we identified a novel pathway by which wayward axonal proteins that reach the dendritic plasma membrane are targeted to lysosomes. These results redefine how axonal proteins achieve their polarized distribution, a crucial requirement for elucidating the underlying molecular mechanisms. [Media: see text] [Media: see text] [Media: see text] [Media: see text]

Download Full-text

Diachronous Tibetan Plateau landscape evolution derived from lava field geomorphology

10.5194/egusphere-egu2020-1270 ◽

2020 ◽

Author(s):

Mark Allen ◽

Robert Law

Keyword(s):

Tibetan Plateau ◽

Landscape Evolution ◽

Tectonic Geomorphology ◽

Normal Faults ◽

The Tibetan Plateau ◽

Lava Field ◽

Northern Tibetan Plateau ◽

Tectonic Processes ◽

Stepwise Evolution

Evolution of the Tibetan Plateau is important for understanding continental tectonics because of its exceptional elevation (~5 km above sea level) and crustal thickness (~70 km). Patterns of long-term landscape evolution can constrain tectonic processes, but have been hard to quantify, in contrast to established datasets for strain, exhumation and paleo-elevation. This study analyses the relief of the bases and tops of 17 Cenozoic lava fields on the central and northern Tibetan Plateau. Analyzed fields have typical lateral dimensions of 10s of km, and so have an appropriate scale for interpreting tectonic geomorphology. Fourteen of the fields have not been deformed since eruption. One field is cut by normal faults; two others are gently folded with limb dips <6o. Relief of the bases and tops of the fields is comparable to modern, internally-drained, parts of the plateau, and distinctly lower than externally-drained regions. The lavas preserve a record of underlying low relief bedrock landscapes at the time they were erupted, which have undergone little change since. There is an overlap in each area between younger published low-temperature thermochronology ages and the oldest eruption in each area, here interpreted as the transition between the end of significant (>3 km) exhumation and plateau landscape development. This diachronous process took place between ~32.5o - ~36.5o N between ~40 and ~10 Ma, advancing northwards at a long-term rate of ~15 km/Myr. Results are consistent with incremental northwards growth of the plateau, rather than a stepwise evolution or synchronous uplift.

Download Full-text