Climate variability in central equatorial Africa: Influence from the Atlantic sector.

We document a strong teleconnection between Central Equatorial African (CEA) rainfall (and Congo River discharge) and the large-scale circulation over the North Atlantic, throughout the boreal winter/spring season. Positive rainfall anomalies over CEA (at interannual and multi-annual timescales) are related to anomalous westerly mid-tropospheric zonal winds over the CEA/Atlantic region. These anomalies appear to be part of a coherent structure of zonal wind anomalies extending to the polar regions of the North Atlantic, similar to that associated with the NAO pattern. Idealised model simulations suggest that at least over the tropical and subtropical latitudes of the Atlantic/African sector such a signal may be associated with SST forcing from the Tropical North Atlantic (TNA) region. We conclude that TNA SSTs may force these circulation anomalies over CEA at multi-annual timescales but at interannual timescales they may be relatively independent of TNA SSTs

Atmospheric controls on mineral dust emission from the Bodélé Depression, Chad: The role of the low level jet

Atmospheric aerosols play an important though uncertain role in the Earth's climate system. The Bodélé Depression in Chad stands out as the planet's largest source of dust, yet very little is known about the atmospheric circulation that maintain this source. We investigate what key large-scale features of the circulation over the Bodélé account for its primacy as a mineral aerosol source. We show, for the first time, the structure and characteristics of the Bodélé Low Level Jet (LLJ) which has a maximum speed near 18°N, 19°E at 925 hPa. It is strongest in the northern winter, receding with the advance of summer in phase with dustiness in the Bodélé. Variability of dust over the Bodélé occurs contemporaneously with the ridging of the Libyan High and pulsing of the pressure gradient which drives the northeasterlies in which the LLJ is embedded

Exotic matter on singular divisors in F-theory

We analyze exotic matter representations that arise on singular seven-brane configurations in F-theory. We develop a general framework for analyzing such representations, and work out explicit descriptions for models with matter in the 2-index and 3-index symmetric representations of SU($N$) and SU(2) respectively, associated with double and triple point singularities in the seven-brane locus. These matter representations are associated with Weierstrass models whose discriminants vanish to high order thanks to nontrivial cancellations possible only in the presence of a non-UFD algebraic structure. This structure can be described using the normalization of the ring of intrinsic local functions on a singular divisor. We consider the connection between geometric constraints on singular curves and corresponding constraints on the low-energy spectrum of 6D theories, identifying some new examples of apparent "swampland" theories that cannot be realized in F-theory but have no apparent low-energy inconsistency.Comment: 71 page

How does a developmental relationship mentoring model affect toxicity experienced in mentoring relationships?

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Detection of Exotic Massive Hadrons in Ultra High Energy Cosmic Ray Telescopes

We investigate the detection of exotic massive strongly interacting hadrons (uhecrons) in ultra high energy cosmic ray telescopes. The conclusion is that experiments such as the Pierre Auger Observatory have the potential to detect these particles. It is shown that uhecron showers have clear distinctive features when compared to proton and nuclear showers. The simulation of uhecron air showers, and its detection and reconstruction by fluorescence telescopes is described. We determine basic cuts in observables that will separate uhecrons from the cosmic ray bulk, assuming this is composed by protons. If these are composed by heavier nucleus the separation will be much improved. We also discuss photon induced showers. The complementarity between uhecron detection in accelerator experiments is discussed.Comment: 9 page 9 figure