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Figure S1. Beggâ s test for publication bias on pre-bronchodilator FEV1 (L). Figure S2. Meta-regression plot of mean difference for pre-bronchodilator FEV1 (L) predicted by treatment duration. Figure S3. Meta-regression plot of mean difference for pre-bronchodilator FEV1 (L) predicted by asthma severity. Figure S4. Meta-regression plot of mean difference for pre-bronchodilator FEV1 (L) predicted by concomitant treatment. Figure S5. The effect of CRTH2 antagonists used as monotherapy or add-on therapy versus placebo on pre-bronchodilator FEV1% predicted. Figure S6. The effect of CRTH2 antagonists used as monotherapy or add-on therapy versus placebo on post-bronchodilator FEV1 (L). Figure S7. The effect of CRTH2 antagonists used as monotherapy or add-on therapy versus placebo on FVC. Figure S8. The effect of CRTH2 antagonists used as monotherapy or add-on therapy versus placebo on severe adverse events. Figure S9. The effect of CRTH2 antagonists used as monotherapy or add-on therapy versus placebo on treatment related adverse events. Figure S10. The effect of CRTH2 antagonists used as monotherapy or add-on therapy versus placebo on adverse events leading to treatment withdrawal. Figure S11. Beggâ s test for publication bias on adverse event. Figure S12. Meta-regression plot of risk ratio for adverse events predicted by treatment duration. Figure S13. Meta-regression plot of risk ratio for adverse events predicted by concomitant treatment. Figure S14. Meta-regression plot of risk ratio for adverse events predicted by asthma severity. (DOCX 10650 kb)

We report the synthesis of boron-doped graphene by thermally annealing the mixture of graphene oxide and boric acid, and its usage as the support of Pt catalyst towards the methanol oxidation reaction. The composition, structure and morphology of boron-doped graphene and its supported Pt nanoparticles (Pt/BG) are characterized by transmission electron microscopy, inductively coupled plasma mass spectrometry, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. It is revealed that boron atoms are doped into graphene network in the form of BC 2 O and BCO 2 bonds, which lead to the increase in defect sites and facilitate the subsequent deposition of Pt nanoparticles. Therefore, the Pt/BG catalyst presents smaller particle size and narrower size distribution than the graphene supported Pt (Pt/G) catalyst. When evaluated as the electrocatalyst for the methanol oxidation reaction, the Pt/BG catalyst exhibits excellent electrochemical activity and stability demonstrated by cyclic voltammetry and chronoamperometry tests. The enhanced activity is mainly ascribed to the electronic interaction between boron-doped graphene and Pt nanoparticles, which lowers the d-band center of Pt and thus weakens the absorption of the poisoning intermediate CO. Our work provides an alternative approach of improving the reaction kinetics for the oxidation of small organic molecules.

The performance of gasoline direct injection (GDI) engine is simulated using the AVL-FIRE code. The effects of four piston shapes on mixture formation and combustion are compared and analyzed. For GDI engines with forward tumble and multihole high-pressure injector, a piston with flat top surface and pit is beneficial for the maintenance of in-cylinder turbulence intensity. Such structure aids in the formation of a combustible mixture around the spark plug at the time of ignition. A piston with a smoother top surface strengthens the turbulence kinetic energy at the time of ignition, thereby accelerating combustion and increasing in-cylinder temperature and pressure. The higher in-cylinder temperature and pressure promote NO emission, whereas soot emission decrease because of subsequent oxidation.

To enhance the electrocatalytic activity of anode catalysts used in alkaline-media direct methanol fuel cells (DMFCs), a Ni@PdPt electrocatalyst was successfully prepared using a three-phase-transfer method. The Ni@PdPt electrocatalyst was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM) techniques. The experimental results indicate that the average particle size of the core–shell-structured Ni@PdPt electrocatalyst is approximately 5.6 nm. The Ni@PdPt electrocatalyst exhibits a catalytic activity 3.36 times greater than that of PdPt alloys for methanol oxidation in alkaline media. The developed Ni@PdPt electrocatalyst offers a promising alternative as a highly electrocatalytically active anode catalyst for alkaline DMFCs.

A unique dataset of coincident high-altitude passive microwave and electric field observations taken by the NASA ER-2 aircraft is used to assess the feasibility of estimating electric fields above electrified clouds using ubiquitous global and multidecadal satellite products. Once applied to a global dataset, such a product would provide a unique approach for diagnosing and monitoring the current sources of the global electric circuit (GEC).In this study an algorithm has been developed that employs ice scattering signals from 37- and 85-GHz passive microwave observations to characterize the electric fields above clouds overflown by the ER-2 aircraft at nearly 20-km altitude. Electric field estimates produced by this passive microwave algorithm are then compared to electric field observations also taken by the aircraft to assess its potential future utility with satellite datasets. The algorithm is shown to estimate observed electric field strengths over intense convective clouds at least 71% (58%) of the time over land and 43% (40%) of the time over the ocean to within a factor of 2 from 85-GHz (37 GHz) passive microwave observations. Electric fields over weaker clouds can be estimated 58% (41%) of the time over land and 22% (8%) of the time over the ocean from 85-GHz (37 GHz) passive microwave observations. The accuracy of these estimates is limited by systematic errors in the observations along with other factors. Despite these sources of error, the algorithm can produce reasonable estimates of electric fields over carefully selected individual electrified clouds that differ from observations by less than 20 V m−1 for clouds that produce 200–400 V m−1 electric fields at 20 km.

Catalyst supports are known to play important role in governing overall catalyst activity and durability. Here, a new type of SnO2–TiO2 solid solution (TixSn1-xO2) support was prepared via a solvothermal method with substitution of Ti4+ by Sn4+ in the TiO2 lattice. Furthermore, the TixSn1-xO2 was combined with conventional carbon black (Vulcan XC-72) to prepare a hybrid support (TixSn1-xO2–C) for depositing Pt nanoparticles. The ratios of Sn vs. Ti in the solid-solution and TixSn1-xO2 vs. XC-72 were systematically optimized in terms of their performance as supports for methanol oxidation. Compared to Pt/TiO2–C and commercial Pt/C catalysts, the best performing Pt/Ti0.9Sn0.1O2–C catalyst exhibited the highest activity, evidenced by methanol oxidation and CO stripping experiments. The well-dispersed Pt nanoparticles (2–3 nm) are mostly deposited on the boundaries of Ti0.9Sn0.1O2 and carbon blacks. Formation of the special triple junction structure can play an important role in improving Pt utilization with increased electrochemical active surface areas (ESA) of Pt. In addition, the enhanced activity for Pt supported on Ti0.9Sn0.1O2–C is due to high content of OH group on Ti0.9Sn0.1O2 along with the strengthened metal-supports interactions. Both promote the oxidation of poisoning CO absorbed on Pt active sites.

By grouping the contiguous precipitating area detected by the precipitation radar on board the Global Precipitation Mission (GPM) core satellite, snapshots of precipitation systems are summarized as precipitation features (PFs), and their properties are cataloged from 1 year GPM observations. These PFs are categorized by their area and depth and convective intensity based on the 20 and 40 dBZ radar echo tops, respectively. The largest PFs are found mainly over ocean at the mid-high latitudes, especially over southern ocean. The deepest PFs are mainly over tropical land, the West Pacific Warm Pool, and the Great Plains of the United States and Argentina. The most convectively intense PFs are dominant over land regions, including midlatitude and high latitude. The zonal precipitation contribution from extremely large precipitation systems is greater in midlatitude and high latitude than in the tropics. These extreme precipitation systems are rare but contribute significantly to the global precipitation. It is important to include their impacts in global climate models to correctly describe the global water cycle.

A novel Ni2+ and Ti3+ co-doped porous black anatase TiO2 is successfully synthesized by a facile sol–gel technique combined with an in situ solid-state chemical reduction approach, followed by mild calcinations (350 °C) in argon atmosphere. The obtained photocatalysts are characterized in detail by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance, N2 adsorption, and transmission electron microscopy. The results indicate that the Ni2+ and Ti3+ elements are co-doped into the lattice of anatase TiO2. The prepared Ni2+/Ti3+ co-doped black anatase TiO2 possesses a mesoporous structure, consisting of disordered Ti3+ and oxygen vacancy layers. Based on UV-vis diffuse reflectance spectra and valence band analysis, the doped Ni2+ and Ti3+ species can significantly narrow the band gap of anatase TiO2 due to the formation of mid-gap states, which allows utilization of visible-light and prevents fast recombination of photogenerated charges effectively. Furthermore, the prepared co-doped photocatalysts exhibit unprecedented higher photocatalytic activity than that of the pure TiO2 and the Ni2+ doped TiO2. The degradation ratio of methyl orange and rhodamine B is up to 95.38 and 95.86%, respectively, within 150 min irradiation of visible-light by the obtained Ni2+/Ti3+ co-doped porous black anatase TiO2. The high visible-light photocatalytic degradation performance may be ascribed to the efficient doping of Ni2+ and Ti3+ in favor of the absorption of visible-light and the separation of photogenerated charges, and the porous structure facilitating the diffusion of reactants and products.

Methacrylated poly(γ-glutamic acid) (mPGA) was introduced to the spongy poly(ethylene glycol)-co-2-hydroxyethyl methacrylate (PEG-HEMA) cryogels. A suitable amount (

Polymer electrolyte membrane (PEM) is one of the key components in direct methanol fuel cells. However, the PEM usually gets attacked by reactive oxygen species during the operation period, resulting in the loss of membrane integrity and formation of defects. Herein, a double-layered catalyst cathode electrode consisting of Pt/CeO2-C as inner catalyst and Pt/C as outer catalyst is fabricated to extend the lifetime and minimize the performance loss of DMFC. Although the maximum power density of membrane electrode assembly (MEA) with catalyst cathode is slightly lower than that of the traditional one, its durability is significantly improved. No obvious degradation is evident in the MEA with double-layered catalyst cathode within durability testing. These results indicated that Pt/CeO2-C as inner cathode catalyst layer greatly improved the stability of MEA. The significant reason for the improved stability of MEA is the ability of CeO2to act as free-radical scavengers.

Background To assess the level of asthma control achieved with budesonide/formoterol in Chinese patients with asthma, based on the Global Initiative for Asthma (GINA) definition and Asthma Control Test (ACT) score. Methods This multicenter, cross-sectional study (NCT01785901) evaluated asthma control levels in Chinese patients receiving physician-prescribed budesonide/formoterol treatment. Adults with a diagnosis of asthma ≥6 months and receiving budesonide/formoterol treatment ≥3 months before screening were consecutively enrolled. Data including medical and medication history were collected using face-to-face questionnaires and physical examinations during a single visit. Results A total of 1483 asthma out-patients from 27 medical centers were enrolled; 217 (14.6%) were treated with budesonide/formoterol using a fixed-dose strategy and 1266 (85.4%) with the SMART (Symbicort ® Maintenance And Reliever Therapy) strategy. According to GINA criteria, asthma was controlled in 58.6% (95% CI: 56.1%–61.1%) of patients and was either controlled or partly controlled in 94.1% (95% CI: 92.8%–95.3%) of patients. According to ACT score, asthma was completely controlled in 22.4% (95% CI: 20.3%–24.6%) of patients and was either completely or well controlled in 83.3% (95% CI: 81.4%–85.2%) of patients. Multivariate logistic regression analysis revealed that a >5-year history of asthma and an age of >50 years were factors associated with lower levels of asthma control. Conclusions This study demonstrated high levels of asthma control (GINA: controlled and partly controlled and ACT: completely and well controlled) in Chinese patients with asthma treated with budesonide/formoterol. Greater age and a longer disease history were associated with lower levels of asthma control. Trial registration ClinicalTrials.govNCT01785901. Registered February 5, 2013.

Roles of lung volumes in asthma remain controversial. We aimed to evaluate the efficacy of lung volumes in differentiating asthma severity levels. Consecutive outpatients with chronic persistent asthma were enrolled, and body plethysmography (BP) and helium dilution (HD) were performed simultaneously to extract RV%pred, TLC%pred, and RV/TLC. Significant negative correlations were found between FEV1%pred and RV%pred (r = −0.557, P 1 in identifying asthma severity levels.

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Latent heating (LH) from precipitation systems with different sizes, depths, and convective intensities is quantified with 15 years of LH retrievals from version 7 Precipitation Radar (PR) products of the Tropical Rainfall Measuring Mission (TRMM). Organized precipitation systems, such as mesoscale convective systems (MCSs; precipitation area > 2000 km2), contribute to 88% of the LH above 7 km over tropical land and 95% over tropical oceans. LH over tropical land is mainly from convective precipitation, and has one vertical mode with a peak from 4 to 7 km. There are two vertical modes of LH over tropical oceans. The shallow mode from about 1 to 4 km results from small, shallow, and weak precipitation systems, and partially from congestus clouds with radar echo top between 5 and 8 km. The deep mode from 5 to 9 km is mainly from stratiform precipitation in MCSs. MCSs of different regions and seasons have different LH vertical structure mainly due to the different proportion of stratiform precipitation. MCSs over ocean have a larger fraction of stratiform precipitation and a top-heavy LH structure. MCSs over land have a higher percentage of convective versus stratiform precipitation, which results in a relatively lower-level peak in LH compared to MCSs over the ocean. MCSs during monsoons have properties of LH in between those typical land and oceanic MCSs. Consistent with the diurnal variation of precipitation, tropical land has a stronger LH diurnal variation than tropical oceans with peak LH in the late afternoon. Over tropical oceans in the early morning, the shallow mode of LH peaks slightly earlier than the deep mode. There are almost no diurnal changes of MCSs LH over oceans. However, the small convective systems over land contribute a significant amount of LH at all vertical levels in the afternoon, when the contribution of MCSs is small.

To provide a better representation of natural ice clouds, a novel ice cloud model is developed by assuming an ice cloud to consist of an ensemble of hexagonal columns and 20-element aggregates with specific habit fractions at each particle size bin. The microphysical and optical properties of this two-habit model (THM) are compared with both laboratory and in situ measurements, and its performance in downstream satellite remote sensing applications is assessed. The ice water contents and median mass diameters calculated based on the THM closely agree with in situ measurements made during 11 field campaigns. In this study, the scattering, absorption, and polarization properties of ice crystals are calculated with a combination of the invariant imbedding T matrix, pseudo-spectral time domain, and improved geometric-optics methods over an entire practical range of particle sizes. The phase functions, calculated based on the THM, show close agreement with counterparts from laboratory and in situ measurements and from satellite-based retrievals. When the THM is applied to the retrievals of cloud microphysical and optical properties from MODIS (the Moderate Resolution Imaging Spectroradiometer) observations, excellent spectral consistency is achieved; specifically, the retrieved cloud optical thicknesses based on the visible/near infrared bands and the thermal infrared bands agree quite well. Furthermore, a comparison between the polarized reflectivities observed by the PARASOL satellite and from theoretical simulations illustrates that the THM can be used to represent ice cloud polarization properties.

With 15 yr of the Tropical Rainfall Measuring Mission (TRMM) observations, the passive microwave radiometers [TRMM Microwave Imager (TMI)] and the precipitation radar (PR) report a close geographical distribution of annual precipitation between 36°S and 36°N. However, large discrepancies between PR and TMI precipitation retrievals are also found over several specific regions, such as central Africa, the Amazon, the tropical east Pacific, and north Indian Ocean. To understand these discrepancies, the PR near-surface and the TMI surface precipitation retrievals are compared at both pixel and precipitation system levels using collocated pixels and a precipitation feature database from 1998 to 2012. Over land, the TMI overestimates precipitation in deep and intense convective systems, but misses significant amounts of warm rainfall in shallow systems. Over the ocean, because of the partial beam filling of large footprints of the lower-frequency sensors, the TMI reports a larger precipitation area than the PR and underestimates the precipitation rate in the convective precipitation region. The TMI tends to overestimate precipitation compared to the PR in a large proportion of shallow systems over the tropical east Pacific and trade wind regions with large-scale descent. The PR tends to overestimate precipitation compared to the TMI in a large proportion of shallow systems over rainy oceans, such as the west Pacific and the Atlantic ITCZ. All these findings imply that there are still large uncertainties in the precipitation climatology over some regions. Further ground validation campaigns are still needed, especially over the ocean.

Background Many asthmatic patients have coexisting allergic rhinitis (AR). This study aims to investigate the compliance of physicians with respiratory medicine specialty (PRMs) to Global Initiative for Asthma (GINA) and Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines during the management of their asthma-AR patients. Methods This cross-sectional questionnaire study surveyed the diagnostic methods and treatment patterns for asthma-AR comorbidity by PRMs from 98 hospitals across China. Results PRMs reported an estimated prevalence of asthma-AR comorbidity of >30% at their clinics. PRMs with greater work experience and a higher professional title estimated treating a significantly higher proportion of patients with AR within the previous month (p = 0.002 and p 90%); however, knowledge gaps existed in their concepts of AR and asthma-AR comorbidity. Thus, further education is warranted for PRMs regarding the importance of AR in asthma patients, definitive diagnosis (allergy tests), classifications of AR, and treatment guidelines for the asthma-AR comorbidity.

Ce 0.8 Sn 0.2 O 2− δ solid solution is fabricated using a simple one-step solvothermal method. The synthesized solid solution mixed with Vulcan XC-72 carbon black (denoted by Ce 0.8 Sn 0.2 O 2− δ –C) is employed as a co-catalytic support for Pt catalysts toward methanol electrooxidation. X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N 2 adsorption/desorption and temperature programmed reduction (TPR) are used to characterize the properties of Ce 0.8 Sn 0.2 O 2− δ solid solution. The results show that Ce 0.8 Sn 0.2 O 2− δ possesses a high specific surface area, an enhanced conductivity and a high oxygen storage capacity (OSC). Pt catalysts grown around Ce 0.8 Sn 0.2 O 2− δ on carbon black form a special Pt–Ce 0.8 Sn 0.2 O 2− δ –C triple junction structure, and their electrocatalytic properties are investigated in detail by a series of electrochemical methods. As compared with Pt/CeO 2 –C and commercial Pt/C catalysts, Pt/Ce 0.8 Sn 0.2 O 2− δ –C catalyst exhibits superior electrocatalytic activity and long-term stability for methanol electrooxidation in acid media. The origin of the enhanced electroctatlytic properties for Pt/Ce 0.8 Sn 0.2 O 2− δ –C is closely related to the OSC of Ce 0.8 Sn 0.2 O 2− δ and the triple junction structure.

Over the eastern Pacific, recent studies have shown that a shallow large-scale meridional circulation with its return flow just above the boundary layer coexists with a deep Hadley circulation. This study examines how the vertical structure of large-scale circulations is related to satellite-observed individual precipitation properties over the eastern Pacific in boreal autumn. Three reanalysis datasets are used to describe differences in their behavior. The results are compared among reanalyses and three distinctly different convection periods, which are defined according to their radar echo depths. Shallow and deep circulations are shown to often coexist for each of the three periods, resulting in the multicell circulation structure. Deep (shallow) circulations preferentially appear in the mostly deep (shallow) convection period of radar echo depths. Thus, depth of convection basically corresponds to which circulation branch is dominant. This anticipated relationship between the circulation structure and depths of convection is common in all three reanalyses. Notable differences among reanalyses are found in the mid- to upper troposphere in either the time-mean state or the composite analysis based on the convection periods. Reanalyses have large variations in characteristics associated with deep circulations such as the upper-tropospheric divergence and outflows and the midlevel inflows, which are consistent with their different profiles of latent heating in the mid- to upper troposphere. On the other hand, discrepancies in shallow circulations and shallow convection are also found, but they are not as large as those in deep ones.

The effects of reformed exhaust gas recirculation (REGR) on combustion and emissions of dimethyl ether (DME) homogeneous charge compression ignition (HCCI) engines are studied by multi-dimensional CFD coupled with chemical kinetic model. The results show that REGR combing EGR and DME reformed gases (DRG) improves combustion and emissions. REGR can delay ignition time by both EGR and DRG, and makes main combustion closer to top dead center (TDC), which is beneficial to reducing compression negative work and broadening load range of HCCI engines. The interaction of DRG and EGR helps avoid too high pressure rise rate or low power performance when being applied independent of each other. HC, CO and NO x emissions can be controlled simultaneously by REGR. Both advantages of DRG and EGR are used to decrease the emissions of HCCI engines by REGR, while the disadvantages of high emissions are alleviated when one of them is applied.

A carbon-riveted PtRu/C catalyst of high stability has been prepared by in situ glucose carbonization using a hydrothermal method (GICH). Its mode of action and its practical application have been investigated by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, a single-fuel cell test, and by conventional electrochemical measurements. The single-fuel cell test has demonstrated that the GICH hydrothermal method has high applicational usefulness. After 100 h the maximum power density of a single cell using carbon-riveted PtRu/C as anode catalyst fell by only 12.0%, from 76.6 to 67.4 mW cm−2, compared with 28.4%, from 73.2 to 52.4 mW cm−2, for traditionally prepared PtRu/C. In addition, when the optimal hydrothermal treatment time was 4 h and the level of carbon coating was 9%, a carbon-riveted PtRu/C catalyst with a 3.5 nm carbon coating gave the best stability, with similar initial activity to traditionally prepared PtRu/C. The significantly increased stability of carbon-riveted PtRu/C may be attributed to two factors: (1) the anchoring effect of the carbon nanolayer formed during in situ glucose carbonization by the hydrothermal method; and (2) the increased content of Pt(0), Ru(0), sp3-hybridized carbon and the C–OR group composition, and the clear decrease in PtO2 and RuOxHy following the carbon-riveting procedure.

Vitamin D deficiency and insufficiency are increasingly being recognized in the general population over the last few decades. However, a number of other disorders have now been linked to vitamin D deficiency and insufficiency, including asthma and COPD. The aim of this study was to evaluate the evidence on the effect of vitamin D on asthma and COPD. We searched electronic databases including SCI, EMBASE, Ovid, and PubMed. Reviewers working independently and in duplicate extracted study characteristics, quality, and the outcomes. The weighted mean differences across trials and random-effect meta-analysis were used to pool the relative risks (RR). This is the first meta-analysis about the risk of vitamin D deficiency for asthma and COPD. Ten studies were available for this meta-analysis and systematic review. The prevalence of vitamin D deficiency was significantly greater among cases than control subjects [RR=1.59, 95%CI=1.07-2.36, 488/812 (60%) vs 278/875 (32%)] for asthma. However, vitamin D insufficiency was not significantly associated with asthma [RR=1.09, 95%CI=0.91-1.30, 702/996 (70%) vs 665/1016 (65%)]. Moreover, studies failed to demonstrate that COPD patients had an increased risk for vitamin D deficiency or insufficiency compared to controls (RR=0.89, 95%CI=0.63-1.25). Vitamin D deficiency was associated with a significant decrease in lung function in asthmatic children. Vitamin D deficiency was highly prevalent in asthma patients, and vitamin D status was associated with lung function. COPD cannot be considered as completely free of vitamin D deficiency.

Aim:Effects of azithromycin on asthma reported in clinical trials are less consistent. We aimed to further clarify the efficacy and safety of azithromycin in treatment of asthma.Methods:The protocol registration number was CRD42017074318 (http://www.crd.york.ac.uk/Prospero). We searched PubM

The effect of the environment on individual clouds makes it difficult to isolate the signal of the aerosol indirect effect, particularly at larger spatial and temporal scales. This study uses observations from the Tropical Rainfall Measuring Mission (TRMM), CloudSat, and Aqua satellites to identify convective cloud systems in clean and dirty environments. The Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol index is collocated with radar precipitation features (RPFs) from TRMM and congestus cloud features (CFs) from CloudSat. The Interim ECMWF Re-Analysis (ERA-Interim) is interpolated to identify the environmental profile surrounding each feature. Regions in Africa, the Amazon, the Atlantic Ocean, and the southwestern United States are examined. TRMM features in the Africa and Amazon regions are more intense and have higher lightning flash rates under dirty background conditions. RPFs in the southwestern United States are more intense under clean background conditions. The Atlantic region shows little difference in intensity. The differences found in the mean thermodynamic profile for RPFs forming in clean and dirty environments could explain these differences in convective intensity.Congestus identified with CloudSat show smaller differences between clouds forming in clean and dirty environments in Africa and the Amazon. Congestus in clean environments have higher reflectivities and generally larger widths, but no trend is seen in cloud-top height. The signal of the aerosol indirect effect is so small that it is very difficult to detect confidently using these methods. The environment must be considered in any study of the aerosol indirect effect, because important environmental changes can occur as aerosols are introduced to an air mass.

Understanding the interactions between allergic rhinitis (AR) and asthma is important for asthma management. This study explored the clinical features of AR as a comorbidity in Chinese asthmatic patients and its impact on asthma control.This cross-sectional survey was conducted among 20 051 patients with asthma in an out-patient setting and covered all of the territories of China. The patients were interviewed face-to-face. A standardized questionnaire was completed by each patient. AR was defined according to the ARIA criteria. The level of asthma control was assessed by the Asthma Control Test. A score ≤19 indicated poorly controlled asthma.AR was present in 69.9% of patients with asthma. Of them, 72.4% had intermittent symptoms, and 93.1% presented with moderate/severe symptoms. Cold air, irritant air and household mites were the most common triggers for AR. A higher percentage of patients with AR experienced poorly controlled asthma compared with those without AR (56.2% versus 51.5%, p 0.001). AR was associated with an increased risk of poorly controlled asthma [odds ratio (OR): 1.21, p 0.001]. Moderate/severe or persistent symptoms were associated with a higher risk of poorly controlled asthma than those with mild or intermittent symptoms (OR: 2.34 and 1.78, respectively, p 0.001). In contrast, diagnosed AR (OR: 0.84, p 0.001), being currently treated with medication (OR: 0.91, p = 0.004) and a prior skin prick test (OR: 0.90, p = 0.003) showed a significantly negative association with poorly controlled asthma.This study confirms that concomitant AR and asthma are highly prevalent in China and that AR is associated with poor asthma control.

This study adopts a "precipitation object" approach by using 14 years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Feature (PF) and National Centers for Environmental Prediction (NCEP) reanalysis data to study rainfall structure and environmental factors associated with extreme heavy rain events. Characteristics of instantaneous extreme volumetric PFs are examined and compared to those of intermediate and small systems. It is found that instantaneous PFs exhibit a much wider scale range compared to the daily gridded precipitation accumulation range. The top 1% of the rainiest PFs contribute over 55% of total rainfall and have 2 orders of rain volume magnitude greater than those of the median PFs. We find a threshold near the top 10% beyond which the PFs grow exponentially into larger, deeper, and colder rain systems. NCEP reanalyses show that midlevel relative humidity and total precipitable water increase steadily with increasingly larger PFs, along with a rapid increase of 500 hPa upward vertical velocity beyond the top 10%. This provides the necessary moisture convergence to amplify and sustain the extreme events. The rapid increase in vertical motion is associated with the release of convective available potential energy (CAPE) in mature systems, as is evident in the increase in CAPE of PFs up to 10% and the subsequent dropoff. The study illustrates distinct stages in the development of an extreme rainfall event including: (1) a systematic buildup in large-scale temperature and moisture, (2) a rapid change in rain structure, (3) explosive growth of the PF size, and (4) a release of CAPE before the demise of the event.

[1] Cumulus congestus clouds have long been identified as an important part of the spectrum of convective clouds in the tropics. These clouds—which range in size from growing cumulus to slightly smaller than a cumulonimbus—make important contributions to precipitation and latent heat fluxes in the tropics. Past studies have used numerical simulations and satellite observations to examine these clouds globally, although definitions of congestus vary between studies. In this study, congestus in the tropics are identified using contiguous cloud area with cloud tops between 5 and 8 km from 5 years of CloudSat reflectivity data. Alternatively, congestus clouds are defined by contiguous cloud areas with infrared brightness temperature ranging from 273 to 260 K and radar-detected surface rainfall from 14 years of Tropical Rainfall Measuring Mission (TRMM) data. Due to the resolution of CloudSat, the congestus identified using this method represent groups of congestus clouds rather than individual turrets. The regional, seasonal variations of the population of congestus are presented globally. Congestus clouds are found most frequently over the Amazon. There is a strong diurnal variation of congestus clouds over land with a peak in the early afternoon shown by TRMM. General differences are found between the properties of congestus over land and those over ocean, especially the shapes of groups of congestus over land and ocean. Ocean congestus clusters are more bell shaped, while land congestus clusters tend to have flatter sides and larger area above the freezing level. These differences have important implications in the proper representation of congestus in numerical models.

The concept of pseudospectra was introduced by Trefethen during the 1990s and became a popular tool to explain the behavior of non-normal matrices. In this paper, we propose a fast algorithm for computing the pseudospectra of Toeplitz matrices by using fast Toeplitz QR factorization. Numerical experiments are given to illustrate the efficiency of the new algorithm.

[1] Both ground and space borne radars have shown that radar reflectivity profiles below the freezing level have different slopes over land and ocean in general. This is critical in correctly estimating the surface precipitation rate in the usual situation in which the radar reflectivity cannot be measured as close to the surface as one would like. Using 14 years of Tropical Rainfall Measuring Mission precipitation radar observations, the variations of slopes of the radar reflectivity in the low troposphere are examined over the stratiform and convective precipitation regions. Radar reflectivity below the freezing level usually decreases toward the surface over land, but increases toward the surface over the ocean. Increasing reflectivity toward the surface is hypothesized to occur mainly when raindrops grow while falling through low clouds, which is favored by high humidity at low levels, and by updraft speeds lower than the fall speed of raindrops, both more likely over oceans. Other things being equal, proxy evidence is presented that the more intense the convection, the more likely reflectivity is to decrease toward the surface, and that this is at least as important as low-level relative humidity. Over monsoon regions with more moderate convection but higher humidity, such as southeast China and the Amazon, there are more profiles with reflectivity increasing toward the surface than over other continental regions such as Africa. Radar reflectivity tends to increase toward the surface in shallow warm rain systems in trade cumulus regions, but tends to decrease toward the surface when high reflectivity values are present at or above the freezing level.

Passive microwave (PMW) satellite-based precipitation over land algorithms rely on physical models to define the most appropriate channel combinations to use in the retrieval, yet typically require considerable empirical adaptation of the model for use with the satellite measurements. Although low-frequency channels are better suited to measure the emission due to liquid associated with rain, most techniques to date rely on high-frequency, scattering-based schemes since the low-frequency methods are limited to the highly variable land surface background, whose radiometric contribution is substantial and can vary more than the contribution of the rain signal. Thus, emission techniques are generally useless over the majority of the Earth's surface. As a first step toward advancing to globally useful physical retrieval schemes, an intercomparison project was organized to determine the accuracy and variability of several emissivity retrieval schemes. A three-year period (July 2004-June 2007) over different targets with varying surface characteristics was developed. The PMW radiometer data used includes the Special Sensor Microwave Imagers, SSMI Sounder, Advanced Microwave Scanning Radiometer (AMSR-E), Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), Advanced Microwave Sounding Units, and Microwave Humidity Sounder, along with land surface model emissivity estimates. Results from three specific targets in North America were examined. While there are notable discrepancies among the estimates, similar seasonal trends and associated variability were noted. Because of differences in the treatment surface temperature in the various techniques, it was found that comparing the product of temperature and emissivity yielded more insight than when comparing the emissivity alone. This product is the major contribution to the overall signal measured by PMW sensors and, if it can be properly retrieved, will improve the utility of emission techniques for over land precipitation retrievals. As a more rigorous means of comparison, these emissivity time series were analyzed jointly with precipitation data sets, to examine the emissivity response immediately following rain events. The results demonstrate that while the emissivity structure can be fairly well characterized for certain surface types, there are other more complex surfaces where the underlying variability is more than can be captured with the PMW channels. The implications for Global Precipitation Measurement-era algorithms suggest that physical retrievals are feasible over vegetated land during the warm seasons.

A new type of Ce-doped α-MoO

Electrified clouds are known to play a major role in the Global Electric Circuit. These clouds produce upward currents which maintain the potential difference between earth's surface and the upper atmosphere. In this study, model output from two simulations of the Community Earth System Model (CESM) are compared with conduction currents and other data derived from the Tropical Rainfall Measuring Mission (TRMM) satellite, including both the lightning imaging sensor (LIS) and precipitation radar (PR). The intention is to determine CESM's skill at representing these microphysical and dynamical properties of clouds. Then, these cloud properties are used to develop a model parameterization to compute conduction currents from electrified clouds. Specifically, we evaluate the ability of global mean convective mass flux, ice water path and convective precipitation to represent conduction current sources. Parameterizations using these variables yield derived global mean currents that agree well with the geographical patterns of TRMM currents. In addition, comparing the diurnal variations of modeled global mean current to the observed diurnal variations of electric potential gradient, root mean square (RMS) errors range between 6.5% and 8.1%, but the maximum occurs 4 to 6 hours early in all three variables. Output currents derived from the model variables generally match well to the currents derived from TRMM, and the total global current estimates agree well with past studies. This suggests that cloud parameters are well suited for representing the global distribution and strength of currents in a global model framework.

Objective: Analyze the prevalence rate and clinicalcharacteristics of severe asthma in China. Methods: Through the analysis of relevant data of China Asthma and Risk factors Epidemiologic investigation (CARE study).Using multi-stage random cluster sampling method, epidemiological survey was performed on asthma prevalence in Chinese residents over 14 years old in 8 provinces(cities)the. Detailed epidemiological data was collected via face-to-face home visit interview among 2034 asthmatics whowere diagnosed in the last epidemiology survey from 2009 to 2010. Asthma was diagnosed based on case history, clinical signs and lung function test. The SPSS12.0 software was applied for statistical analysis and the status of asthma control was investigated. Results: According to the questionnaire survey, The “severe asthma” prevalence rate was 5.99% (122/2034) without differences in both genders. In the 61 ∼ 70 age group and the patients whose education level were below primary school, severe asthma had the highest percentages (8.31%, and > 8% respectively). Compared with asthma patients who do not smoke, smokers were more likely to suffer severe asthma (OR = 1.663, 95% CI [1.150 ∼ 2.404]). Conclusions: The prevalence of severe asthma is similar in China and other regions.Severe asthma in elderly patients was more prevalent. Smoking may be a risk factor for severe asthma.

The Ezh2 gene is an important member of the polycomb-group (PcG) family. As a newly identified oncogene, the expression of Ezh2 has been shown to be significantly increased in prostate cancer, breast cancer, renal cell carcinoma and hepatic cancer; however, a role for Ezh2 in the occurrence of glioma has not yet been reported. In this study, we found that the Ezh2 gene is highly expressed in U87 human glioma cells. Using RNA interference, we demonstrated that the downregulation of Ezh2 expression in U87 human glioma cells resulted in apoptosis and a cell cycle arrest in the G0/G1 phase. In addition, we found that silencing of the Ezh2 gene altered the mitochondrial membrane potential and promoted the release of cytochrome c from the mitochondria. Furthermore, the reduced expression of Ezh2 altered the Bax and Bcl-2 protein levels and led to the activation of caspase 9 and 3. These results indicate that the apoptosis induced in U87 human glioma cells by the silencing of the Ezh2 gene is related to the mitochondrial pathway.

This study investigates a long-duration mesoscale system with extremely heavy rainfall over southwest Taiwan during the Terrain-influenced Monsoon Rainfall Experiment (TiMREX). This mesoscale convective system develops offshore and stays quasi-stationary over the upstream ocean and southwest coast of Taiwan. New convection keeps developing upstream offshore but decays or dies after moving into the island, dropping the heaviest rain over the upstream ocean and coastal regions. Warm, moist, unstable conditions and a low-level jet (LLJ) are found only over the upstream ocean, while the island of Taiwan is under the control of a weak cold pool. The LLJ is lifted upward at the boundary between the cold pool and LLJ. Most convective clusters supporting the long-lived rainy mesoscale system are initiated and develop along that boundary. The initiation and maintenance is thought to be a “back-building–quasi-stationary” process. The cold pool forms from previous persistent precipitation with a temperature depression of 2°–4°C in the lowest 500 m, while the high terrain in Taiwan is thought to trap the cold pool from spreading or moving. As a result, the orography of Taiwan is “extended” to the upstream ocean and plays an indirect effect on the long-duration mesoscale system.

Using 13 yr of data from the Tropical Rainfall Measuring Mission (TRMM) satellite, a regional climatology of monsoonal precipitation is created for portions of the southwest United States. The climatology created using precipitation features defined from the TRMM precipitation radar (PR) shows that the population of features includes a large number of small, weak features that do not produce much rain and are very shallow. A lesser percentage of large, stronger features contributes most of the region’s rainfall. Dividing the features into categories based on the median values of volumetric rainfall and maximum height of the 30-dBZ echo is a useful way to visualize the population of features, and the categories selected reflect the life cycle of monsoonal convection. An examination of the top rain-producing features at different elevations reveals that extreme features tend to occur at lower elevations later in the day. A comparison with the region studied in the North American Monsoon Experiment (NAME) shows that similar diurnal patterns occur in the Sierra Madre Occidental region of Mexico. The population of precipitation features in both regions is similar, with the NAME region producing slightly larger precipitation systems on average than the southwest United States. Both regions on occasion demonstrate the pattern of convection initiating at high elevations and moving downslope while growing upscale through the afternoon and evening; however, there are also days on which convection remains over the high terrain.

The Copper-doped cobalt oxide films have been prepared onto titanium support by reactive DC magnetron sputtering. The deposits are characterized by X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), Ultroviolet (UV) and scanning electron microscope (SEM). The electrochemical characteristics of deposits are explored by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The effect of copper content in the Cu–Co oxides on the surface morphology, electrochemical and crystallographic properties has been investigated. The introduction of Cu element makes the Cu–Co oxides deposit fine and further lead to high roughness of deposits, which is helpful for the oxides’ electrochemical performance. Based on the electrochemical determination, the binary oxide electrodes exhibit better catalysis activity than that of CuO and Co 3 O 4 electrodes for oxygen evolution reaction (OER). The increase OER activity has been attributed to the enlarged surface roughness and the new active sites of deposits, according to the results of EIS.

A specialized satellite version of the passive microwave electric field retrieval algorithm (Peterson et al., 2015) is applied to observations from the Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (GPM) satellites to estimate the generator current for the Global Electric Circuit (GEC) and compute its temporal variability. By integrating retrieved Wilson currents from electrified clouds across the globe, we estimate a total mean current of between 1.4 kA (assuming the 7% fraction of electrified clouds producing downward currents measured by the ER-2 is representative) to 1.6 kA (assuming all electrified clouds contribute to the GEC). These current estimates come from all types of convective weather without preference, including Electrified Shower Clouds (ESCs). The diurnal distribution of the retrieved generator current is in excellent agreement with the Carnegie curve (RMS difference: 1.7%). The temporal variability of the total mean generator current ranges from 110% on semi-annual timescales (29% on an annual timescale) to 7.5% on decadal timescales with notable responses to the Madden-Julian Oscillation and El Nino Southern Oscillation. The geographical distribution of current includes significant contributions from oceanic regions in addition to the land-based tropical chimneys. The relative importance of the Americas and Asia chimneys compared to Africa is consistent with the best modern ground-based observations and further highlights the importance of ESCs for the GEC.

During the past few decades, the Sahara Desert has become even hotter. Satellite observations suggest that this warming has led to a rise in the frequency of extreme storms in the Sahel region of West Africa. See Letter p.475 A warming climate is expected to increase the frequency of extreme rainfall events because warmer air can support higher humidity, but other mechanisms may also be at work. Christopher Taylor et al. show that increases in extreme rainfall in the western Sahel region of Africa since 1982 are driven by a larger gradient in temperature across the region caused by a warmer Sahara desert to the north. In turn, the sharper gradient increases wind shear and seems to have led to the frequency of mesoscale convective systems—which are exactly the kind of weather systems likely to generate extreme rainfall—tripling since 1982. The spatial patterns of global warming are likely to further increase the temperature gradient and intensify mesoscale convective systems, leading to more extreme rainfall events.

There are presently different types of air conditioning products in China such as room air conditioners, variable speed room air conditioners, unity air conditioners, multi-connected air-condition (heat pump) unit, chilled water air conditioning systems. For these air conditioning products, evaluation indexes have been created, respectively including energy efficiency ratio (EER), coefficient of performance (COP), seasonal energy efficiency ratio (SEER) and integrated part load value (IPLV), and their energy efficiency standards have been established. Based on thermodynamic perfectibility, this paper makes the compatible analysis of the energy efficiency and thermodynamic perfectibility gradient of energy efficiency standards for different air conditioning products. According to testing conditions of evaluation indexes, these air conditioning products are classified into two groups, the standard rating conditions group (EER, COP) and the variable working condition group (SEER, IPLV). The results show the thermodynamic perfectibility of different air conditioning products grade as the same level for energy efficiency standards in each group differ from one another. Besides, the average thermodynamic perfectibility gradient of energy efficiency levels for air conditioning product in the standard rating conditions group is basically the same, and that of variable speed room air conditioners and multi-connected air-condition (heat pump) unit are the highest and lowest, respectively.

The rainfall contributions from precipitation features (PFs) with full spectra of different sizes and convective intensities over the tropics and subtropics are summarized using 12 yr of version 6 Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and Microwave Imager (TMI) observations. Regional, seasonal, and diurnal variations of the rainfall contributions from various PFs are shown, with the global distribution of the sizes, PR echo tops, maximum heights of 30 dBZ, and minimum TMI 85-GHz brightness temperatures of PFs above which contribute half of the rainfall in each 2° × 2° region. Though the results from radar and microwave observations generally agree with each other, some large differences exist over land. Seasonal variations of sizes and intensities of precipitation systems are found over the northeast Pacific, northern SPCZ, and some land areas in addition to the well-known monsoon regions. The diurnal cycles of rainfall over land and ocean are interpreted with the combinations of life cycles of various precipitation systems, using the diurnal variations of rainfall contributions from precipitation systems with different sizes and intensities. The long-duration rainfall events with more than four consecutive 3-h periods with rain at a grid point are identified from 11 yr of TRMM 3B42 products. These “12-h rain events” contribute a larger proportion of the total rainfall over ocean than over land. They are mostly correlated with precipitation systems with large sizes and intense convection. However, they can also be caused by some shallow persistent precipitation systems, such as those over the northeast slope of the Andes in Peru in spring and fall and over the west coast of India in summer.

The Tropical Rainfall Measuring Mission (TRMM) satellite has provided invaluable data for tropical cyclone (TC) research since December 1997. The challenge, however, is how to analyze and efficiently utilize all of the information from several instruments on TRMM that observe the same target. In this study, a tropical cyclone precipitation, cloud, and convective cell feature (TCPF) database has been developed by using observations of the TRMM precipitation radar (PR), Microwave Imager (TMI), Visible and Infrared Scanner (VIRS), Lightning Imaging System (LIS), and the TRMM 3B42 rainfall product. The database is based on an event-based method that analyzes the measurements from multiple sensors. This method condenses the original information of pixel-level measurements into the properties of events, which can significantly increase the efficiency of searching and sorting the observed historical TCs. With both convective and rainfall properties included, the database offers the potential to aid the research aiming to improve both TC intensification and rainfall forecasts. Using the TRMM TCPF database, regional variations of TC convection and diurnal variations of TC rainfall are examined. In terms of absolute number, the northwest Pacific Ocean basin has the deepest and most intense TCPFs according to IR, radar, and 85-GHz microwave measurements. However, the North Atlantic TCPFs appear to have the highest lightning production. Globally, TC rainfall has a maximum at 0430–0730 local solar time (LST) and a minimum around 1930–2230 LST. However, after separating ocean from land, a distinct difference is seen. Over land, the diurnal variation of TC rainfall shows double peaks: one around 0130–0730 LST and the other at 1630–1930 LST. The minimum is at 1030–1330 LST.

In this paper, the blend membranes based on sulfonated poly(ether ether ketone) and sulfonated cyclodextrin as the proton conducting membranes for DMFCs usage are prepared and investigated. The incorporation of sulfonated cyclodextrin in SPEEK membranes is evaluated by the characteristic absorptions of FT-IR spectra. Thermal stability and micro-morphology of the blend membranes are determined by thermogravimetry analysis and scanning electron microscope tests. The properties of the blend membranes are investigated such as swelling behavior, methanol permeability and proton conduction as function of the fraction of sulfonated cyclodextrin. The methanol crossover could be suppressed by the incorporation of sulfonated cyclodextrin and the methanol permeability decreases when the methanol concentration increases from 2.5 M to 20 M. Proton conduction is also promoted by the introduction of sulfonated cyclodextrin and the proton conductivity increases with the increase of sulfonated cyclodextrin content. The calculated activation energy for proton conduction of the blend membranes is very low and the maximum value is 4.20 kJ mol−1, which is much lower than that of Nafion 115 (9.15 kJ mol−1, measured in our experiments). These data indicate that proton can transport easily through the blend membranes. The selectivity of the blend membranes, a compromise between proton conductivity and methanol permeability, is much higher than that of Nafion 115 at the sulfonated cyclodextrin content above 15 wt.%. The blend membranes with 15, 20, and 25 wt.% of sulfonated cyclodextrin are assembled in the practical DMFCs and their polarization curves with 2.5 M and 8.0 M methanol solution are determined, respectively. The membrane with 20 wt.% sulfonated cyclodextrin reaches the highest power density of 29.52 mW cm−2 at 120 mA cm−2 and 8.0 M methanol solution. These results suggest the potential usage of the SPEEK membranes incorporating with sulfonated cyclodextrin in DMFCs.

Moist convection is well known to be generally more intense over continental than maritime regions, with larger updraft velocities, graupel, and lightning production. This study explores the transition from maritime to continental convection by comparing the trends in Tropical Rainfall Measuring Mission (TRMM) radar and microwave (37 and 85 GHz) observations over islands of increasing size to those simulated by a cloud-resolving model. The observed storms were essentially maritime over islands of 10 000 km2, with a gradual transition in between. Equivalent radar and microwave quantities were simulated from cloud-resolving runs of the Weather Research and Forecasting model via offline radiation codes. The model configuration was idealized, with islands represented by regions of uniform surface heat flux without orography, using a range of initial sounding conditions without strong horizontal winds or aerosols. Simulated storm strength varied with initial sounding, as expected, but also increased sharply with island size in a manner similar to observations. Stronger simulated storms were associated with higher concentrations of large hydrometeors. Although biases varied with different ice microphysical schemes, the trend was similar for all three schemes tested and was also seen in 2D and 3D model configurations. The successful reproduction of the trend with such idealized forcing supports previous suggestions that mesoscale variation in surface heating—rather than any difference in humidity, aerosol, or other aspects of the atmospheric state—is the main reason that convection is more intense over continents and large islands than over oceans. Some dynamical storm aspects, notably the peak rainfall and minimum surface pressure low, were more sensitive to surface forcing than to the atmospheric sounding or ice scheme. Large hydrometeor concentrations and simulated microwave and radar signatures, however, were at least as sensitive to initial humidity levels as to surface forcing and were more sensitive to the ice scheme. Issues with running the TRMM simulator on 2D simulations are discussed, but they appear to be less serious than sensitivities to model microphysics, which were similar in 2D and 3D. This supports the further use of 2D simulations to economically explore modeling uncertainties.

This paper describes the preparation of SiO2 stabilized Pt/C catalyst (SiO2/Pt/C) by the hydrolysis of alkoxysilane, and examines the possibility that the SiO2/Pt/C is used as a durable cathode catalyst for proton exchange membrane fuel cells (PEMFCs). TEM and XRD results revealed that the hydrolysis of alkoxysilane did not significantly change the morphology and crystalline structure of Pt particles. The SiO2/Pt/C catalyst exhibited higher durability than the Pt/C one, due to the facts that the silica layers covered were beneficial for reducing the Pt aggregation and dissolution as well as increasing the corrosion resistance of supports, although the benefit of silica covering was lower than the case of Pt/CNT catalyst. Also, it was observed that the activity of the SiO2/Pt/C catalyst for the oxygen reduction reaction was somewhat reduced compared to the Pt/C one after the silica covering. This reduction was partially due to the low oxygen kinetics as revealed by the rotating-disk-electrode measurement. Silica covering by hydrolysis of only 3-aminopropyl trimethoxysilane is able to achieve a good balance between the durability and activity, leading to SiO2/Pt/C as a promising cathode catalyst for PEMFCs.

A compact planar 4 : 1 unequal Wilkinson power divider using artificial transmission lines has been designed, fabricated and experimentally verified in this paper. Instead of adopting conventional quarter-wave microstrip transmission lines, artificial transmission lines realized by a series of meandered-line inductors, parallel-plate and interdigital capacitors are employed to implement an unequal power divider of the conventional Wilkinson topology. The proposed 4 : 1 unequal power divider occupies 52.1 mm × 28.1 mm, which is about 17% of a conventional one. The measured results of the power divider are in good agreement with the simulated ones. The measurements show that such a 4 : 1 unequal Wilkinson power divider at operational frequency ranging from 0.7 GHz to 1.1 GHz has a phase imbalance less than 4 degrees and power split between 4.06 and 4.3. The impedance matching at all ports exhibits in return losses more than 12 dB, and the good isolation between the two output ports is greater than 19 dB. Mo...

This paper describes improvements to the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) land rainfall algorithm in version 7 (v7) of the TRMM data products. The correlations between rain rates and TMI 85-GHz brightness temperatures (Tb) for convective and stratiform rain are generated using 7 years of collocated TMI and TRMM precipitation radar (PR) data. The TMI algorithm for estimating the convective ratio of rainfall is also modified. This paper highlights both the improvements in the v7 algorithm and the continuing problems with the land rainfall retrievals. It is demonstrated that the proposed changes to the algorithm significantly lower the overestimation by TMI globally and over large sections of central Africa and South America. Also highlighted are the problems with the 2A12 land algorithm that have not been addressed in the version 7 algorithm, such as large regional and seasonal dependence of biases in the TMI rain estimates, and potential changes to the algorithm to resolve these problems are discussed.

The long-standing mainstay of support for C. T. R. Wilson’s global circuit hypothesis is the similarity between the diurnal variation of thunderstorm days in universal time and the Carnegie curve of electrical potential gradient. This rough agreement has sustained the widespread view that thunderstorms are the “batteries” for the global electrical circuit. This study utilizes 10 years of Tropical Rainfall Measuring Mission (TRMM) observations to quantify the global occurrence of thunderstorms with much better accuracy and to validate the comparison by F. J. W. Whipple 80 years ago. The results support Wilson’s original ideas that both thunderstorms and electrified shower clouds contribute to the DC global circuit by virtue of negative charge carried downward by precipitation. First, the precipitation features (PFs) are defined by grouping the pixels with rain using 10 years of TRMM observations. Thunderstorms are identified from these PFs with lightning flashes observed by the Lightning Imaging Sensor. PFs without lightning flashes but with a 30-dBZ radar echo-top temperature lower than −10°C over land and −17°C over ocean are selected as possibly electrified shower clouds. The universal diurnal variation of rainfall, the raining area from the thunderstorms, and possibly electrified shower clouds in different seasons are derived and compared with the diurnal variations of the electric field observed at Vostok, Antarctica. The result shows a substantially better match from the updated diurnal variations of the thunderstorm area to the Carnegie curve than Whipple showed. However, to fully understand and quantify the amount of negative charge carried downward by precipitation in electrified storms, more observations of precipitation current in different types of electrified shower clouds are required.

Two novel compact substrate integrated waveguide (SIW) band-pass filters are presented in this work. They operate in dual mode at 5.8 GHz with high selectivity of a relative bandwidth of 2% and 5%, respectively. The filter has the dimension of λg × 0.6 λg, which is about 60% of a conventional SIW dual-mode band-pass filter. Simulation and measurements agree well. The empirical design formulae are presented as well.