Measurements of the light-absorbing material inside cloud droplets and its effect on cloud albedo

Most of the measurements of light-absorbing aerosol particles made previously have been in non-cloudy air and therefore provide no insight into aerosol effects on cloud properties. Here, researchers describe an experiment designed to measure light absorption exclusively due to substances inside cloud droplets, compare the results to related light absorption measurements, and evaluate possible effects on the albedo of clouds. The results of this study validate those of Twomey and Cocks and show that the measured levels of light-absorbing material are negligible for the radiative properties of realistic clouds. For the measured clouds, which appear to have been moderately polluted, the amount of elemental carbon (EC) present was insufficient to affect albedo. Much higher contaminant levels or much larger droplets than those measured would be necessary to significantly alter the radiative properties. The effect of the concentrations of EC actually measured on the albedo of snow, however, would be much more pronounced since, in contrast to clouds, snowpacks are usually optically semi-infinite and have large particle sizes

Minimizing Black Bear Problems at New York State Public Campgrounds

The black bear\u27s omnivorous foraging behavior has been both beneficial and detrimental to its coexistence with modern humans. The ability to feed on a variety of animal and vegetable matter, alive or dead, has been advantageous to the black bear\u27s survival as its range has diminished. Although black bears have an innate aversion to people, many have learned to tolerate humans to acquire easily obtainable high energy concentrated artificial foods. Human carelessness in the storage and disposal of foods within or near bear habit at has resulted in conflicts between campers and wild bears. Forest Preserve public campgrounds create a unique situation by concentrating people and food in remote forested environments frequented by black bears. The failure to effectively deal with this situation resulted in chronic bear-human problems at approximately one-third of New York\u27s Forest Preserve public campgrounds. In addition to loss of food, some people suffered property damage and a few sustained physical injuries. Alleviation of bear nuisance activity typically included attempts to capture and relocate bothersome bears. The high cost and ultimate failure of this approach led to the destruction of many bears while little long-term improvement was achieved

CD19 Signaling Is Impaired in Murine Peritoneal and Splenic B-1 B Lymphocytes

B-1 cells reside predominantly within the coelomic cavities, tonsils, Peyer\u27s patches, spleen (a minor fraction – ∼5%) and are absent in the lymph nodes. They are the primary sources of natural IgM in the body. B-1 cells express polyreactive B cell receptors (BCRs) that cross react with self-antigens and are thus implicated in auto-immune disorders. Previously, we reported that peritoneal B-1 cells are deficient in CD19-mediated intracellular signals leading to Ca2+ mobilization. Here, we find that splenic B-1 cells, like peritoneal B-1 cells, are defective in Ca2+ release upon B cell activation by co-cross-linking BCR and CD19. In the absence of extracellular sources of Ca2+, intracellular Ca2+ flux is similar between B-1 and B-2 cells. Moreover, the intracellular component of Ca2+ release in both subsets of B cells is mostly PI3K dependent. BCR and CD19 co-cross-linking activates Akt, a key mediator of survival and proliferation signals downstream of PI3K in splenic B-2 cells. Splenic B-1 cells, on the other hand, do not phosphorylate Akt (S473) upon similar treatment. Furthermore, BCR + CD19 cross-linking induced phosphorylation of JNK is much reduced in splenic B-1 cells. In contrast, B-1 cells exhibited increased levels of constitutively active pLyn which appears to have an inhibitory role. The CD19 induced Ca2+ response and BCR induced proliferation response were restored by a partial inhibition of pLyn with Src kinase specific inhibitors. These findings suggest a defect in CD19-mediated signals in both peritoneal and splenic B-1 B lymphocytes, which is in part, due to higher levels of constitutively active Lyn

Selection at Multiple Checkpoints Focuses VH12 B Cell Differentiation toward a Single B-1 Cell Specificity

Phosphatidyl choline (PtC)-specific B cells segregate to the B-1 subset, where they comprise up to 10% of the B-1 repertoire. About half express VH12 and Vκ4/5H and are restricted in VHCDR3. We have previously reported that anti-PtC VHCDR3 is enriched among VH12-expressing cells by selective elimination of pre-B cells. We report here a bias for Vκ4/5H expression among VH12-expressing B cells, even among those that do not bind PtC and are not B-1. This is due in part to an inability of VH12 to associate with many light (L) chains but must also be due to a selective advantage in survival or clonal expansion in the periphery for Vκ4/5H-expressing cells. Thus, the bias for Vκ4/5H expression is independent of PtC binding, and, as segregation to B-1 occurs after Ig gene expression, it precedes segregation to the B-1 subset. In 6-1 mice, splenic B-1 cells reside in follicles but segregate to follicles distinct from those that contain B-2 cells. These data indicate that selection at multiple developmental checkpoints ensures the co-expression of an anti-PtC VHCDR3 and L chain in a high frequency of VH12 B cells. This focus toward specificity for PtC facilitates the development of a large anti-PtC B-1 repertoire

Investigating Impacts of Health Policies Using Staggered Difference-in-Differences: The Effects of Adoption of an Online Consultation System on Prescribing Patterns of Antibiotics

We use a recently proposed staggered difference-in-differences approach to investigate effects of adoption of an online consultation system in English general practice on antibiotic prescribing patterns. The target estimand is the average effect for each group of practices (defined by year of adoption) in each year, which we aggregate across all adopting practices, by group, and by time since adoption. We find strong evidence of a positive effect of adoption on antibiotic prescribing rates, though the magnitude of effect is relatively small. As time since adoption increases, the effect size increases, while effects vary across groups

B-1 Cell Development: Evidence for an Uncommitted Immunoglobulin (Ig)M + B Cell Precursor in B-1 Cell Differentiation

Murine phosphatidyl choline (PtC)–specific B cells in normal mice belong exclusively to the B-1 subset. Analysis of anti-PtC (VH12 and VH12/Vκ4) transgenic (Tg) mice indicates that exclusion from B-0 (also known as B-2) occurs after immunoglobulin gene rearrangement. This predicts that PtC-specific B-0 cells are generated, but subsequently eliminated by either apoptosis or differentiation to B-1. To investigate the mechanism of exclusion, PtC-specific B cell differentiation was examined in mice expressing the X-linked immunodeficiency (xid) mutation. xid mice lack functional Bruton's tyrosine kinase (Btk), a component of the B cell receptor signal transduction pathway, and are deficient in B-1 cell development. We find in C57BL/ 6.xid mice that VH12 pre-BII cell selection is normal and that PtC-specific B cells undergo modest clonal expansion. However, the majority of splenic PtC-specific B cells in anti-PtC Tg/xid mice are B-0, rather than B-1 as in their non-xid counterparts. These data indicate that PtC-specific B-0 cell generation precedes segregation as predicted, and that Btk function is required for efficient segregation to B-1. Since xid mice exhibit defective B cell differentiation, not programmed cell death, these data are most consistent with an inability of PtC-specific B-0 cells to convert to B-1 and a single B cell lineage

Single cell analysis shows decreasing FoxP3 and TGFβ1 coexpressing CD4+CD25+ regulatory T cells during autoimmune diabetes

Natural CD4+CD25+ regulatory T (CD4+CD25+ T reg) cells play a key role in the immunoregulation of autoimmunity. However, little is known about the interactions between CD4+CD25+ T reg cells and autoreactive T cells. This is due, in part, to the difficulty of using cell surface markers to identify CD4+CD25+ T reg cells accurately. Using a novel real-time PCR assay, mRNA copy number of FoxP3, TGFβ1, and interleukin (IL)-10 was measured in single cells to characterize and quantify CD4+CD25+ T reg cells in the nonobese diabetic (NOD) mouse, a murine model for type 1 diabetes (T1D). The suppressor function of CD4+CD25+CD62Lhi T cells, mediated by TGFβ, declined in an age-dependent manner. This loss of function coincided with a temporal decrease in the percentage of FoxP3 and TGFβ1 coexpressing T cells within pancreatic lymph node and islet infiltrating CD4+CD25+CD62Lhi T cells, and was detected in female NOD mice but not in NOD male mice, or NOR or C57BL/6 female mice. These results demonstrate that the majority of FoxP3-positive CD4+CD25+ T reg cells in NOD mice express TGFβ1 but not IL-10, and that a defect in the maintenance and/or expansion of this pool of immunoregulatory effectors is associated with the progression of T1D

Minimum-error discrimination between three mirror-symmetric states

We present the optimal measurement strategy for distinguishing between three quantum states exhibiting a mirror symmetry. The three states live in a two-dimensional Hilbert space, and are thus overcomplete. By mirror symmetry we understand that the transformation {|+> -> |+>, |-> -> -|->} leaves the set of states invariant. The obtained measurement strategy minimizes the error probability. An experimental realization for polarized photons, realizable with current technology, is suggested.Comment: 4 pages, 2 figure

Approximate probabilistic verification of hybrid systems

Hybrid systems whose mode dynamics are governed by non-linear ordinary differential equations (ODEs) are often a natural model for biological processes. However such models are difficult to analyze. To address this, we develop a probabilistic analysis method by approximating the mode transitions as stochastic events. We assume that the probability of making a mode transition is proportional to the measure of the set of pairs of time points and value states at which the mode transition is enabled. To ensure a sound mathematical basis, we impose a natural continuity property on the non-linear ODEs. We also assume that the states of the system are observed at discrete time points but that the mode transitions may take place at any time between two successive discrete time points. This leads to a discrete time Markov chain as a probabilistic approximation of the hybrid system. We then show that for BLTL (bounded linear time temporal logic) specifications the hybrid system meets a specification iff its Markov chain approximation meets the same specification with probability $1$. Based on this, we formulate a sequential hypothesis testing procedure for verifying -approximately- that the Markov chain meets a BLTL specification with high probability. Our case studies on cardiac cell dynamics and the circadian rhythm indicate that our scheme can be applied in a number of realistic settings