Daylight during winters and symptoms of depression and sleep problems: A within-individual analysis.

BACKGROUND: With climate change Northern areas of the globe are expected to have less daylight during winters due to less snow and more cloudiness. While wintertime has been linked to mental health problems, the role of wintertime daylight has been scarcely studied. We examined longitudinal associations for wintertime objective exposure to global radiation and self-reported daylight exposure with symptoms of depression and sleep problems. METHODS: Our analytical sample included 15,619 respondents from three Swedish Longitudinal Occupational Surveys of Health (2012, 2014 and 2016). Objective exposure was global radiation (MJ/m2, November-January and November-February). Subjective exposure was based on self-reported time spent outdoors in daylight (<1 h vs. ≥ 1 h, November-January). Symptoms of depression were evaluated using a six-item subscale of the (Hopkins) Symptom Checklist. Fixed-effects method with conditional logistic regression controlled for time-invariant participant characteristics by design and time-varying covariates were added into models. RESULTS: One unit increase in the four-month averaged global radiation was associated with lower odds of depressive symptoms (OR 0.69, 95 % CI 0.52-0.91). These findings were confirmed using four-month cumulative exposure (OR 0.91, 95 % CI 0.85-0.98). Individuals reporting ≥ 1 h exposure to daylight during winter months were less likely to report depressive symptoms (OR 0.72, 95 % CI 0.60-0.82) compared to time when their exposure was < 1 h. Higher three-month exposure to global radiation suggested a protective association for sleep problems. CONCLUSION: These findings suggest that higher exposure to daylight during winters may contribute to lower likelihood of depression symptoms.

Clonal relationships of memory B cell subsets in autoimmune mice.

Immunological memory protects our body from re-infection and it is composed of a cellular and a humoral arm. The B-cell branch with its memory B cells (MBCs), plasma cells and antibodies, formed either in a germinal centre (GC) -dependent or -independent manner, ensure that we can rapidly mount a recall immune response. Previous work in immunised wildtype (WT) mice have identified several subsets of MBCs whereas less is known under autoimmune conditions. Here, we have investigated the heterogeneity of the MBC compartment in autoimmune mouse models and examined the clonal relationships between MBC subsets and GC B cells in one of the models. We demonstrate the presence of at least four different MBC subsets based on their differential expression pattern of CD73, CD80 and PD-L2 in surrogate light chain-deficient (SLC-/-), MRL+/+ and MRLlpr/lpr mice, where most of the MBCs express IgM. Likewise, four MBC subsets could be identified in WT immunised mice. In SLC-/- mice, high-throughput sequencing of Ig heavy chains demonstrates that the two CD73-positive subsets are generally more mutated. Lineage tree analyses on expanded clones show overlaps between all MBC subsets and GC B cells primarily in the IgM sequences. Moreover, each of the three IgM MBC subsets could be found both as ancestor and progeny to GC B cells. This was also observed in the IgG sequences except for the CD73-negative subset. Thus, our findings demonstrate that several MBC subsets are present in autoimmune and WT mice. In SLC-/- mice, these MBC subsets are clonally related to each other and to GC B cells. Our results also indicate that different MBC subsets can seed the GC reaction.

Defective peripheral B cell selection in common variable immune deficiency patients with autoimmune manifestations.

Common variable immune deficiency (CVID) is a heterogeneous disorder characterized by recurrent infections, low levels of serum immunoglobulins, and impaired vaccine responses. Autoimmune manifestations are common, but B cell central and peripheral selection mechanisms in CVID are incompletely understood. Here, we find that receptor editing, a measure of central tolerance, is increased in transitional B cells from CVID patients and that these cells have a higher immunoglobulin κ:λ ratio in CVID patients with autoimmune manifestations than in those with infection only. Contrariwise, the selection pressure in the germinal center on CD27bright memory B cells is decreased in CVID patients with autoimmune manifestations. Finally, functionally, T cell-dependent activation showed that naive B cells in CVID patients are badly equipped for activation and induction of mismatch repair genes. We conclude that central tolerance is functional whereas peripheral selection is defective in CVID patients with autoimmune manifestations, which could underpin the development of autoimmunity.

Validation metrics of homogenization techniques on artificially inhomogenized monthly temperature networks in Sweden and Slovenia (1950-2005).

In order to correctly detect climate signals and discard possible instrumentation errors, establishing coherent data records has become increasingly relevant. However, since real measurements can be inhomogeneous, their use for assessing homogenization techniques is not directly possible, and the study of their performance must be done on homogeneous datasets subjected to controlled, artificial inhomogeneities. In this paper, considering two European temperature networks over the 1950-2005 period, up to 7 artificial breaks and an average of 107 missing data per station were introduced, in order to determine that mean square error, absolute bias and factor of exceedance can be meaningfully used to validate the best-performing homogenization technique. Three techniques were used, ACMANT and two versions of HOMER: the standard, automated setup mode and a manual setup. Results showed that the HOMER techniques performed better regarding the factor of exceedance, while ACMANT was best with regard to absolute error and root mean square error. Regardless of the technique used, it was also established that homogenization quality anti-correlated meaningfully to the number of breaks. On the other hand, as missing data are almost always replaced in the two HOMER techniques, only ACMANT performance is significantly, negatively affected by the amount of missing data.

Brown clouds over South Asia: biomass or fossil fuel combustion?

Carbonaceous aerosols cause strong atmospheric heating and large surface cooling that is as important to South Asian climate forcing as greenhouse gases, yet the aerosol sources are poorly understood. Emission inventory models suggest that biofuel burning accounts for 50 to 90% of emissions, whereas the elemental composition of ambient aerosols points to fossil fuel combustion. We used radiocarbon measurements of winter monsoon aerosols from western India and the Indian Ocean to determine that biomass combustion produced two-thirds of the bulk carbonaceous aerosols, as well as one-half and two-thirds of two black carbon subfractions, respectively. These constraints show that both biomass combustion (such as residential cooking and agricultural burning) and fossil fuel combustion should be targeted to mitigate climate effects and improve air quality.