Surficial Geology of the Chicxulub Impact Crater, Yucatan, Mexico

The Chicxulub impact crater in northwestern Yucatan, Mexico is the primary candidate for the proposed impact that caused mass extinctions at the end of the Cretaceous Period. The crater is buried by up to a kilometer of Tertiary sediment and the most prominent surface expression is a ring of sink holes, known locally as cenotes, mapped with Landsat imagery. This 165 +/- 5 km diameter Cenote Ring demarcates a boundary between unfractured limestones inside the ring, and fractured limestones outside. The boundary forms a barrier to lateral ground water migration, resulting in increased flows, dissolution, and collapse thus forming the cenotes. The subsurface geology indicates that the fracturing that created the Cenote Ring is related to slumping in the rim of the buried crater, differential thicknesses in the rocks overlying the crater, or solution collapse within porous impact deposits. The Cenote Ring provides the most accurate position of the Chicxulub crater's center, and the associated faults, fractures, and stratigraphy indicate that the crater may be approx. 240 km in diameter

Multiple dens invaginatus, mulberry molar and conical teeth : case report and genetic considerations

Dens in dente, also known as dens invaginatus and dilated compound odontoma, is a malformation that can occur on primary, permanent, or supernumerary teeth that is characterized by a deep invagination of the surface of a crown or root covered with enamel. This abnormality in tooth morphology generally affect the maxillary lateral incisors but several cases of multiple dens invaginatus have been reported in the literature. A 15 year-old female patient is reported here presenting five dens invaginatus: four in the permanent mandibular incisors and one in the permanent, maxillary left central incisor, additionally the following dental findings were observed: a permanent mandibular left mulberry molar, molarization of some premolars, several microdontic conoid teeth, retention of five primary teeth, absence of several permanent teeth germs, a macrodontic molar with abnormal roots and several periapical radiolucencies associated to the dens invaginatus. There was no family history of similar dental findings to those observed in the patient. There are several genes that participate in the development of teeth, of those, the following five genes could be implicated as responsible or co-participators for some of the dental anomalies present in this patient: MSX1 (Muscle segment homeobox 1), DLX1 and DLX2 (Distal-less homeobox 1 and 2 genes), PAX9 (Paired box gene) and PITX2 (Pituitary homeobox transciption factor 2)

Pedagogía Crítica en la Era del Autoritarismo: Desafíos y Posibilidades

The discourse of authoritarianism and the echoes of a fascist past resurface.In this context, higher education, beyond favoring practices of freedom, has become an instrumentalized institution in order to reproduce and legitimize dynamics of domination. This article questions this reactionary form of educational and pedagogical action, particularly in its neoliberal version. At the same time, it explores how education can provide the theoretical and practical foundations to rethink its own purpose, together with the very nature of politics. In this sense, this article proposes that education and politics are completely inseparable dimensions

Primary School Vision Screening Involving Teachers in Nampula, Mozambique

Purpose: There is no plan for a national child eye care programme or existing human resource infrastructure to address the immediate challenge of child eye health in Mozambique.This study aims to design, implement and evaluate a school based pediatric vision screening service, to identify those in need of eye care services, among Mozambique’s 11,561,000 children. Methods: Primary School Screening took place in three schools in Nampula, Mozambique in September 2010 and March 2011. The children’s vision was screened by an optometry student, optometrist or teacher with Log MAR ETDRS letters at 4 Meters. Ophthalmoscopy was performed on all children by qualified optometrists. Children requiring refraction were refracted on site, those needing ophthalmological assessment were referred to the ophthalmologist in Nampula Central Hospital. Results: 770 children were screened in total. The ocular abnormality detection rate was 10.65%, and included 7.40% of children requiring spectacle provision, and the remaining 3.25% requiring referral to the Ophthalmology Unit. The distribution of myopia, hyperopia and astigmatism among children provided spectacles was 28.57%, 12.5% and 58.93% respectively, and overall prevalence in the study sample was 2.21%, 0.91% and 4.29% respectively. Referrals for ocular health abnormalities included, cataract (26.92%), ptosis (23.08%), glaucoma (15.38%). All teachers interviewed are eager to participate in a vision screening programme. Two Primary School Teachers were trained in vision screening. Teachers scored 100% case detection agreement with optometrists and student optometrists, with no noted false positive or false negative referrals. Conclusions: Teachers appear to have an adequate level of education and interest to undertake vision screening in children. This study will inform a regional pilot teacher screening project for Nampula, which will include the addition of “Vision Screening” to teacher training modules at Universidade Pedagogica, Nampula, as part of a plan to develop a national child eye care programme for Mozambique

Efectos de varias dosis de magnesio aplicadas al suelo sobre el crecimiento de plántulas de cacao (Theobroma cacao L.).

Cacao-Theobroma caca

Effect of inulin and probiotic bacteria on growth, survival, immune response, and prevalence of white spot syndrome virus (WSSV) in Litopenaeus vannamei cultured under laboratory conditions

The effect of inulin and probiotic bacteria on the growth, survival, immune response and viral prevalence of white spot syndrome virus (WSSV) in white shrimp was evaluated. Presumptive bacilli and lactic acid bacteria (LAB) were characterized for hemolytic and enzymatic activity, hydrophobicity and antagonism against Vibrio. Selected isolates (Bacilli and LAB) were included in the diet of juvenile shrimp. Two bioassays were conducted with treatments by triplicate (10 shrimp per replicate) with inulin and inulin and bacteria. Fourteen LAB and six bacilli isolates had potential as probiotics. Survival and growth was not affected by the addition of the inulin and bacteria to diet. Inulin and bacteria improved immunity in cultured shrimp. Also, these feed additives reduced the prevalence of WSSV in cultured shrimp.Keywords: Probiotics, prebiotics, white spot syndrome virus (WSSV), immune system, Litopenaeus vannameiAfrican Journal of Biotechnology Vol. 12(21), pp. 3366-337

Spontaneous Rotation of a Toric Implantable Collamer Lens

We present a case of toric implantable collamer lens (TICL) spontaneous rotation in a patient with myopic astigmatism. A 23-year-old female underwent TICL implantation. Preoperative uncorrected visual acuity (UCVA) was 20/800 and 20/1200, respectively, with −7.75 −4.25 × 0° and −8.25 −5.25 × 180°. The left eye achieved an UCVA of 20/30. After 3 months of successful implantation of TICL in the left eye, the patient presented with a sudden decrease in visual acuity in the left eye. UCVA was 20/100 with a refraction of +2.50 −4.50 × 165°. We observed the toric marks with a 30° rotation from the original position and decided to reposition the TICL, obtaining a final UCVA of 20/25, which remained stable at 6 months' follow-up. TICL can present a considerable rotation that compromises visual acuity. The relocation of TICL is a safe and effective procedure to recover visual acuity due to significant spontaneous TICL rotation