Euphorbia (Subgen. Chamaesyce Sect. Anisophyllum) jaegeri, a Shrubby New Species from the Deserts of California, United States

Euphorbia jaegeri (Euphorbiaceae), an endemic to southeastern California, United States, is described as new and illustrated with photographs. It is known from two general locations, one in the Orocopia Mountains (Riverside County) and the other in the Marble Mountains and adjacent Bristol Mountains (San Bernardino County). The habitat is desert scrub on rocky hillsides and along arroyos, primarily in rock crevices or gravelly soils, at elevations from approximately 600 to 850 m. The new species belongs to Euphorbia subgen. Chamaesyce sect. Anisophyllum. It is distinguished by the combination of a shrubby habit and involucral appendages that are deeply parted into triangular to subulate segments. The exact affinities of the new species are not obvious, but it is compared with E. polycarpa and E. setiloba. With only four known occurrences, a fragmented distribution, and significant existing and potential threats to most of the populations, E. jaegeri is of high conservation concern

Divergent genetic mechanisms underlie reversals to radial floral symmetry from diverse zygomorphic flowered ancestors

Malpighiaceae possess flowers with a unique bilateral symmetry (zygomorphy), which is a hypothesized adaptation associated with specialization on neotropical oil bee pollinators. Gene expression of two representatives of the CYC2 lineage of floral symmetry TCP genes, CYC2A and CYC2B, demarcate the adaxial (dorsal) region of the flower in the characteristic zygomorphic flowers of most Malpighiaceae. Several clades within the family, however, have independently lost their specialized oil bee pollinators and reverted to radial flowers (actinomorphy) like their ancestors. Here, we investigate CYC2 expression associated with four independent reversals to actinomorphy. We demonstrate that these reversals are always associated with alteration of the highly conserved CYC2 expression pattern observed in most New World (NW) Malpighiaceae. In NW Lasiocarpus and Old World (OW) Microsteria, the expression of CYC2-like genes has expanded to include the ventral region of the corolla. Thus, the pattern of gene expression in these species has become radialized, which is comparable to what has been reported in the radial flowered legume clade Cadia. In striking contrast, in NW Psychopterys and OW Sphedamnocarpus, CYC2-like expression is entirely absent or at barely detectable levels. This is more similar to the pattern of CYC2 expression observed in radial flowered Arabidopsis. These results collectively indicate that, regardless of geographic distribution, reversals to similar floral phenotypes in this large tropical angiosperm clade have evolved via different genetic changes from an otherwise highly conserved developmental program

Una especie nueva de Acidocroton Sección Ophellantha (Euphorbiaceae) de Tabasco, México

The new species Acidocroton madrigalensis is described and illustrated from the state of Tabasco, Mexico. It is known only from the Sierra El Madrigal and the Cerro La Campana, where it is a frequent component of the under story of tropical rain forest, occurring on limestone outcrops. It belongs to section Ophellantha and is characterized by its diminutive, non-spinous stipules, large leaves that are shortly petiolate, and staminate flowers with 20 to 35 stamens. A table is presented that provides the principal differences among A. madrigalensis and the other two species of the genus present in Mexico, A. spinosus y A. steyermarkii.Se describe e ilustra a Acidocroton madrigalensis, una nueva especie del estado de Tabasco, México. Se conoce solamente de la Sierra El Madrigal y el Cerro La Campana, en donde es un componente abundante del estrato bajo en la selva alta perennifolia sobre afloramientos de roca caliza. Pertenece a la sección Ophellantha y se caracteriza por sus diminutas estípulas no espiniformes, hojas grandes y cortamente pecioladas y por tener flores estaminadas con 20 a 35 estambres. Se presenta un cuadro mostrando las diferencias principales entre A. madrigalensisy las otras dos especies del género conocidas de México, A. spinosus y A. steyermarkii

A time-dependent perturbative analysis for a quantum particle in a cloud chamber

We consider a simple model of a cloud chamber consisting of a test particle (the alpha-particle) interacting with two other particles (the atoms of the vapour) subject to attractive potentials centered in $a_1, a_2 \in \mathbb{R}^3$. At time zero the alpha-particle is described by an outgoing spherical wave centered in the origin and the atoms are in their ground state. We show that, under suitable assumptions on the physical parameters of the system and up to second order in perturbation theory, the probability that both atoms are ionized is negligible unless $a_2$ lies on the line joining the origin with $a_1$. The work is a fully time-dependent version of the original analysis proposed by Mott in 1929.Comment: 23 page

High prevalence of urinary schistosomiasis in a desert population: results from an exploratory study around the ounianga lakes in Chad

Background: Researching a water-borne disease in the middle of the Sahara desert might not seem the most relevant concern. However, nomadic Sahelian pastoralist's health concerns regarding their livestock and anecdotal reports about trematode infections of Fasciola spp and Schistosoma spp in desert-raised animals justified an exploratory study focusing on the lakes of Ounianga in Northern Chad. The aim was to test whether trematode parasites such as Schistosoma spp occur in human populations living around the Sahara desert lakes of Ounianga Kebir and Ounianga Saker in northern Chad. Methods: The study comprised of three components. First, a cross sectional survey based on a random sample drawn from the population to detect infections with S. haematobium and S. mansoni ; second, focus group discussions exploring disease priorities, access to health and health seeking behaviour; and third, searching water contact sites for intermediate host snails. Samples of trematode parasites and snails were confirmed on species level by molecular genetics methods. Results: Among 258 participants, the overall S. haematobium prevalence using urine filtration was 39.1% (95% CI 33.2% - 45.1%), with 51.5% of the infected suffering from heavy infection. The intermediate host snail of S. haematobium ( Bulinus truncatus ) occurred at water sites near both study villages, revealing the potential for local transmission. Although a positive S. mansoni POC-CCA test result was obtained from 15.2% (10.6%-19.7%) of the samples no intermediate host snails of S. mansoni were found, and the relevance of S. mansoni remains uncertain. Qualitative findings underline the importance of morbidity caused by urinary schistosomiasis, and the lack of access to diagnostics and treatment as a major health concern. Conclusion: This research revealed a high prevalence of urinary schistosomiasis in the population living around the lakes of Ounianga in the Sahara, a UNESCO world heritage site in Chad. Despite the high public health importance of the associated morbidity expressed by the population there is no access to diagnostics and treatment. Further research is needed to develop and test a context adapted intervention