How large should whales be?

The evolution and distribution of species body sizes for terrestrial mammals is well-explained by a macroevolutionary tradeoff between short-term selective advantages and long-term extinction risks from increased species body size, unfolding above the 2g minimum size induced by thermoregulation in air. Here, we consider whether this same tradeoff, formalized as a constrained convection-reaction-diffusion system, can also explain the sizes of fully aquatic mammals, which have not previously been considered. By replacing the terrestrial minimum with a pelagic one, at roughly 7000g, the terrestrial mammal tradeoff model accurately predicts, with no tunable parameters, the observed body masses of all extant cetacean species, including the 175,000,000g Blue Whale. This strong agreement between theory and data suggests that a universal macroevolutionary tradeoff governs body size evolution for all mammals, regardless of their habitat. The dramatic sizes of cetaceans can thus be attributed mainly to the increased convective heat loss is water, which shifts the species size distribution upward and pushes its right tail into ranges inaccessible to terrestrial mammals. Under this macroevolutionary tradeoff, the largest expected species occurs where the rate at which smaller-bodied species move up into large-bodied niches approximately equals the rate at which extinction removes them.Comment: 7 pages, 3 figures, 2 data table

Mjerenje odbojne polarizacije u reakciji 16^O (→ e , e′ → p)

The longitudinal and transverse components of the polarization of the outgoing proton were measured for the reaction 16^O (→ e , e′ → p) at a four-momentum transfer squared of 0.8 GeV2 in quasifree kinematics. These were the first measurements of polarization transfer observables for a complex nucleus. Comparison of the ratio of the transverse and longitudinal polarization to theoretical predictions allows the study of modification of the proton’s form factors in the nuclear medium.Mjerile su se uzdužna i poprečna komponenta polarizacije izlaznih protona u reakciji 16^O (→ e , e′ → p) za kvadrat prijenosa impulsa od 0.8 GeV2 , u kvazislobodnim kinematičkim uvjetima. Ovo su prva mjerenja prijenosa polarizacije za složenu jezgru. Usporedba omjera poprečne i uzdužne polarizacije s teorijskim predviđanjima omogućava proučavanje promjena faktora oblika protona kada je u nuklearnom okruženju

Mjerenje odbojne polarizacije u reakciji 16^O (→ e , e′ → p)

The longitudinal and transverse components of the polarization of the outgoing proton were measured for the reaction 16^O (→ e , e′ → p) at a four-momentum transfer squared of 0.8 GeV2 in quasifree kinematics. These were the first measurements of polarization transfer observables for a complex nucleus. Comparison of the ratio of the transverse and longitudinal polarization to theoretical predictions allows the study of modification of the proton’s form factors in the nuclear medium.Mjerile su se uzdužna i poprečna komponenta polarizacije izlaznih protona u reakciji 16^O (→ e , e′ → p) za kvadrat prijenosa impulsa od 0.8 GeV2 , u kvazislobodnim kinematičkim uvjetima. Ovo su prva mjerenja prijenosa polarizacije za složenu jezgru. Usporedba omjera poprečne i uzdužne polarizacije s teorijskim predviđanjima omogućava proučavanje promjena faktora oblika protona kada je u nuklearnom okruženju

Mjerenje omjera električnog i magnetskog faktora oblika protona odbojnom polarizacijom

The longitudinal and transverse polarizations of the outgoing proton were measured for the reaction 1H(→ e , e′ → p) at four-momentum transfer squared of 0.5 to 3.5 GeV2 . The ratio of the electric to magnetic form factors of the proton is proportional to the ratio of the transverse to longitudinal polarizations.Mjerila se uzdužna i poprečna polarizacija izlaznih protona u reakciji 1H(→ e , e′ → p) za kvadrate prijenosa četiri-impulsa od 0.5 do 3.5 GeV2 . Omjer električnog i magnetskog faktora oblika protona je razmjeran omjeru poprečne i uzdužne polarizacije

Mjerenje omjera električnog i magnetskog faktora oblika protona odbojnom polarizacijom

The longitudinal and transverse polarizations of the outgoing proton were measured for the reaction 1H(→ e , e′ → p) at four-momentum transfer squared of 0.5 to 3.5 GeV2 . The ratio of the electric to magnetic form factors of the proton is proportional to the ratio of the transverse to longitudinal polarizations.Mjerila se uzdužna i poprečna polarizacija izlaznih protona u reakciji 1H(→ e , e′ → p) za kvadrate prijenosa četiri-impulsa od 0.5 do 3.5 GeV2 . Omjer električnog i magnetskog faktora oblika protona je razmjeran omjeru poprečne i uzdužne polarizacije

New developments in the statistical approach of parton distributions

We recall how parton distributions are constructed in a statistical physical picture of the nucleon. The chiral properties of QCD lead to strong relations between quarks and antiquarks distributions and the importance of the Pauli exclusion principle is also emphasized. A global next-to-leading order QCD analysis of unpolarized and polarized deep-inelastic scattering data allows to determine a small number of free parameters. Some predictions are compared to recent experimental results and we discuss the prospects of this physical framework.Comment: 10 pages, 12 figures. Invited talk presented at the " Corfu Summer Institute on EPP,CORFU2005, Corfu, Greece, September 4-26, 2005. To be published in Journal of Physics, Conference Series (2006

Chapter 6 Collapsible Soils in the UK

Metastable soils may collapse because of the nature of their fabric. Generally speaking, these soils have porous textures, high void ratios and low densities. They have high apparent strengths at their natural moisture content, but large reductions of void ratio take place upon wetting and, particularly, when they are loaded because bonds between grains break down upon saturation. Worldwide, there is a range of natural soils that are metastable and can collapse, including loess, residual soils derived from the weathering of acid igneous rocks and from volcanic ashes and lavas, rapidly deposited and then desiccated debris flow materials such as some alluvial fans; for example, in semi-arid basins, colluvium from some semi-arid areas and cemented, high salt content soils such as some sabkhas. In addition, some artificial non-engineered fills can also collapse. In the UK, the main type of collapsible soil is loess, though collapsible non-engineered fills also exist. Loess in the UK can be identified from geological maps, but care is needed because it is usually mapped as ‘brickearth’. This is an inappropriate term and it is suggested here that it should be replaced, where the soils consist of loess, by the term ‘loessic brickearth’. Loessic brickearth in the UK is found mainly in the south east, south and south west of England, where thicknesses greater than 1 m are found. Elsewhere, thicknesses are usually less than 1 m and, consequently, of limited engineering significance. There are four steps in dealing with the potential risks to engineering posed by collapsible soils: (1) identification of the presence of a potentially collapsible soil using geological and geomorphological information; (2) classification of the degree of collapsibility, including the use of indirect correlations; (3) quantification of the degree of collapsibility using laboratory and/or in situ testing; (4) improvement of the collapsible soil using a number of engineering options