Study of the Aerosol Indirect Effect by Large-Eddy Simulation of Marine Stratocumulus

A total of 98 three-dimensional large-eddy simulations (LESs) of marine stratocumulus clouds covering both nighttime and daytime conditions were performed to explore the response of cloud optical depth (τ) to various aerosol number concentrations (Na = 50–2500 cm−3) and the covarying meteorological conditions (large-scale divergence rate and SST). The idealized First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) and the Atlantic Stratocumulus Transition Experiment (ASTEX) Lagrangian 1 sounding profiles were used to represent the lightly and heavily drizzling cases, respectively. The first and second aerosol indirect effects are identified. Through statistical analysis, τ is found be to both positively correlated with Na and cloud liquid water path (LWP) with a higher correlation associated with LWP, which is predominantly regulated by large-scale subsidence and SST. Clouds with high LWP occur under low SST or weak large-scale subsidence. Introduction of a small amount of giant sea salt aerosol into the simulation lowers the number of cloud droplets activated, results in larger cloud droplets, and initiates precipitation for nondrizzling polluted clouds or precedes the precipitation process for drizzling clouds. However, giant sea salt aerosol is found to have a negligible effect on τ for lightly precipitating cases, while resulting in a relative reduction of τ of 3%–77% (increasing with Na, for Na = 1000–2500 cm−3) for heavily precipitating cases, suggesting that the impact of giant sea salt is only important for moist and potentially convective clouds. Finally, a regression analysis of the simulations shows that the second indirect effect is more evident in clear than polluted cases. The second indirect effect is found to enhance (reduce) the overall aerosol indirect effect for heavily (lightly) drizzling clouds; that is, τ is larger (smaller) for the same relative change in Na than considering the Twomey (first indirect) effect alone. The aerosol indirect effect (on τ) is lessened in the daytime afternoon conditions and is dominated by the Twomey effect; however, the effect in the early morning is close but slightly smaller than that in the nocturnal run. Diurnal variations of the aerosol indirect effect should be considered to accurately assess its magnitude

Dynamics of shape fluctuations of quasi-spherical vesicles revisited

In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed of a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations and a systematic formulation of the theory is also established. From the systematic theoretical formulation, an analytical description of the dynamics of shape fluctuations of quasi-spherical vesicles is derived. In particular, in developing the theory we have made a new interpretation of some of the phenomenological constants in a canonical continuum description of fluid lipid-bilayer membranes and shown the consequences of this new interpretation in terms of the characteristics of the dynamics of vesicle shape fluctuations. Moreover, we have used the systematic formulation of our theory as a framework against which we have discussed the previously existing theories and their discrepancies. Finally, we have made a systematic prediction about the system-dependent characteristics of the relaxation dynamics of shape fluctuations of quasi-spherical vesicles with a view of experimental studies of the phenomenon and also discussed, based on our theory, a recently published experimental work on the topic.Comment: 18 pages, 4 figure

Bis(4-amino­benzoato)-κ2 O,O′;κO-(2,2′-bipyridine-κ2 N,N′)zinc

In the title complex, [Zn(C7H6NO2)2(C10H8N2)], the ZnII cation is coordinated by two amino­benzoate anions and one 2,2′-bipyridine ligand in a distorted trigonal–bipyramidal geometry. The carboxyl­ate group of one aminobenzoate anion coordinates to the ZnII cation in a monodentate manner, whereas the carboxyl­ate group of the other amino­benzoate anion chelates the Zn cation with different Zn—O bond lengths. Inter­molecular N—H⋯N and N—H⋯O hydrogen bonding is present in the crystal structure

ACQUIRING SCOPE: A LONGITUDINAL STUDY

Based on the spontaneous data of a Chinese-speaking child collected from 1 year old up to 4+ years old, this study focuses on the development of his scope by examining the scope interaction between negation and quantified NPs that occur in preverbal positions. It is found that the child is sensitive to scope at 3;2, an age much earlier than the age reported in other studies (e.g., age of 6 in Lee 1991). Further evidence shows that the child has mastered scope of negation and scope in general at the age of 4. First, starting from age 4;3, the child has managed to mark universal quantifiers and wh-phrases as well as duration phrases occurring in the preverbal position with scope markers such as dou ‘all’ and you ‘have’. Second, by the age of 4;5, the child has placed duration phrases in target positions in relation to negation

4,4′-Bipyridine–4-(p-toluene­sulfonamido)­benzoic acid (1/2)

In the title compound, C14H13NO4S·0.5C10H8N2, the two benzene rings are nearly perpendicular to each other [dihedral angle = 83.21 (10)°]. The bipyridine mol­ecule is centrosymmetric, the mid-point of the C—C bond linking the pyridine rings being located on an inversion center. Inter­molecular N—H⋯O and O—H⋯N hydrogen bonds and weak inter­molecular C—H⋯O hydrogen bonds are present in the crystal structure

catena-Poly[[(2,2′-bipyridine)copper(II)]-μ-5-tert-butyl­isophthalato]

In the crystal structure of the title polymeric compound, [Cu(C12H12O4)(C10H8N2)]n, the asymmetric unit consists of one CuII ion, one 5-tert-butyl­isophthalate (tbip) and one 2,2′-bipyridine (bpy) ligand. The copper(II) ion is four-coordin­ated by two N atoms from bipy and two O atoms from two tbip ligands, leading to a distorted tetrahedral coordination. Each tbip ligand adopts a bis-monodentate coordination mode to connect two symmetry-related copper(II) ions, so forming a zigzag polymer chain parallel to [001]. The tert-butyl methyl groups are disordered over two positions with occupancies of 0.506 (6)/0.494 (6

International Security, Development, and Human Rights: Policy Conversion or Conflict?

This article uses an institutional network governance approach to explore the overlapping dimension of the policy fields between security, development, and human rights, reflected in the US and German provincial reconstruction teams (PRTs) in Afghanistan. The past two decades have witnessed a gradually changing paradigm in academic and policy debates regarding the questions of the normative basis of world order and possibilities for tackling imminent threats to security and peace (i.e. intra-state armed conflicts, failed states, terrorism, poverty, and deepening inequality). The introduction of concepts such as “human security” and “the right to humanitarian intervention/responsibility to protect (R2P)” as well as critical examinations of peace-, nation-, and state-building missions (PNSB) have led to a relativist tendency of state sovereignty and a changing attitude regarding how to address the intersection of security, development, and human rights. Despite this shift, the policy commitments to integrating these policy considerations remain puzzling. How have they been redefined, conceptualized, and put into practice? I argue that an integrated conceptual approach has facilitated the redefinition of common policy goals, principles, and the mobilization of resources. At the same time, civil and military cooperation, as demonstrated in the multifunctional work of PRTs, has been Janus-headed—permanently caught in an ongoing tension between the war on terror and short-term stability operation on the one hand and long-term durable peace and development on the other. The misunderstanding of its interim character, the dynamics of Afghan environment, the blurring of policy lines, and the differences between national PRT models have made it difficult to systematically assess the efficiency and legitimacy of each policy frame and program

Filter and Grid Resolution Requirements in LES via a Discontinuous Galerkin Solver

The discontinuous Galerkin (DG) methodology has proven very effective for large eddy simulation (LES) of various turbulent flows. In LES with a given discretization accuracy, two important parameters are the grid resolution $h$ and the filter size $\Delta$. In most of the previous works, the grid spacing is usually set to be proportional to the specified filter size. In this work, the DG method is combined with a subgrid scale (SGS) closure which is equivalent to that of the filtered density function (FDF). Various $\Delta/h$ ratios for LES of a two-dimensional and three-dimensional temporally developing mixing layer are considered, and a systematic parametric study is conducted to investigate the effects of grid resolution, the filter width size, and the order of the spectral discretization. Comparative assessments are made via the use of high resolution direct numerical simulation (DNS) data