¿Por qué prehistoria si hay historia precolombina? (Luis Ferrero)

IntroducciónHacer crítica no es una tarea fácil. Por el contrario es una labor de gran responsabilidad y objetividad. Pero es necesario y debe hacerse con fines constructivos que permitan, en todo caso, contribuir al avance de la ciencia.Comienzo este comentario apoyando la interrogante con la cual titula Luis Ferrero su obra (EUNED, 1986) Coincido plenamente con él en el cuestionamiento que hace con respecto al empleo del concepto de prehistoria. Los avances en este campo de la antropología y de la historia han hecho que desde hace varios años se venga considerando el significado de tal concepto y lo que éste implica. Hace bien el autor en alertar a su público en cuanto a una nueva manera de considerar la prehistoria, uniéndose a autores latinoamericanos y norteamericanos con su preocupación... 

Nitrogen Metabolim in Sheep Fed Hay-Based Diet Supplemented with Yucca schidigera with or without Nisin

Empat ekor domba yang berfistula pada bagian rumen digunakan pada rancangan Bujur sangkar latin 3 x 3. penelitian ini bertujuan untuk mengetahui pengaruh suplementasi Yucca schidigera dengan atau tanpa nisin terhadap penggunaan nitrogen, konsentrasi amonia dalam rumen, konsentrasi nitrogen urea dalam plasma, suplai nitrogen mikroba pada domba yang diberi pakan basal hay rumput timothy dan konsentrat. Tiga perlakuan pakan yaitu pakan basal (kontrol), pakan basal + Yucca schidigera 240 ppm (yucca), pakan basal + Yucca schidigera 240 ppm + nisin 6 mg/kg BW 0.75 (yucca+nisin). Ekskresi nitrogen dalam urin domba yang diberi perlakuan yucca+nisin lebih rendah (P<0.05) dibandingkan perlakuan kontrol. Perlakuan yucca+nisin meningkatkan keseimbangan nitrogen sebesar 8 % dibandingkan kontrol. Konsentrasi amonia  dalam rumen pada perlakuan yucca dan yucca+nisin lebih rendah (P<0.05) daripada perlakuan kontrol, dan konsentrasi tersebut masih berada diatas konsentrasi minimal untuk pertumbuhan mikroba dalam rumen. Konsentrasi nitrogen urea dalam plasma tidak dipengaruhi oleh perlakuan dan bervariasi antara 20.8 – 22.0 mg/dl. Suplai nitrogen mikroba pada perlakuan yucca dan yucca+nisin lebih tinggi (P<0.05) dibandingkan perlakuan kontrol. Berdasarkan hasil penelitian ini dapat disimpulkan bahwa suplementasi yucca atau kombinasi yucca dan nisin dapat menurunkan konsentrasi amonia dalam rumen, sehingga menurunkan ekskresi nitrogen pada urin dimana hal ini berimplikasi positif dalam mengurangi pencemaran nitrogen di lingkungan. (Animal Production 7(1): 34-39 (2005) Kata kunci : Yucca schidigera, Nisin, Penggunaan N, N Mikroba

Radiographic outcomes over time after endoscopic anterior scoliosis correction

A prospective, consecutive series of 106 patients receiving endoscopic anterior scoliosis correction. The aim was to analyse changes in radiographic parameters and rib hump in the two years following surgery. Endoscopic anterior scoliosis correction is a level sparing approach, therefore it is important to assess the amount of decompensation which occurs after surgery. All patients received a single anterior rod and vertebral body screws using a standard compression technique. Cleared disc spaces were packed with either mulched femoral head allograft or rib head/iliac crest autograft. Radiographic parameters (major, instrumented, minor Cobb, T5-T12 kyphosis) and rib hump were measured at 2,6,12 and 24 months after surgery. Paired t-tests and Wilcoxon signed ranks tests were used to assess the statistical significant of changes between adjacent time intervals.----- Results: Mean loss of major curve correction from 2 to 24 months after surgery was 4 degrees. Mean loss of rib hump correction was 1.4 degrees. Mean sagittal kyphosis increased from 27 degrees at 2 months to 30.6 degrees at 24 months. Rod fractures and screw-related complications resulted in several degrees less correction than patients without complications, but overall there was no clinically significant decompensation following complications. The study concluded that there are small changes in deformity measures after endoscopic anterior scoliosis surgery, which are statistically significant but not clinically significant.

Completing the jigsaw : ESL and EFL undergraduate views on interactive peer-based learning

English as a Second Language (ESL) and English as a Foreign Language (EFL) students often face incongruence with Western teaching methods and learning expectations. The aim of this paper is to explore the potential for interactive peer-based learning to engage ESL and EFL language learners provide authentic communication experiences and accelerate learning through two case studies in different contexts. A study was undertaken to investigate student ‘voice’ (Rudduck, 1999, 2005; Rudduck & Flutter, 2004) during an intervention of communicative language teaching using peer-based learning strategies. This article describes unique similarities and subtle differences between ESL and EFL undergraduate learning in two different cultural contexts, using a 'stages of learning matrix' teaching tool to encourage civic skills and self-efficacy. It also suggests ways for teachers to improve on inconsistencies in group-based learning in order to promote more inclusive and congruent learning experiences for English language learners.

Case study of collaborative learning in two contexts : what do English language learners gain?

This chapter describes the use of collaborative learning as an approach to enhance English language learning by students from non-English speaking backgrounds. Communicative Language Teaching (CLT) principles were applied to two case studies, one comprising of undergraduate English as Foreign Language Learners in Turkey and the other involved English as Second Language learners in Australia. Social constructivism inspired communicative language teaching using collaborative learning activities such as team work, interactive peer-based learning, and iterative stages of learning matrix were incorporated to enhance students' learning outcomes. Data collected after the CLT intervention was made up of field notes, reflective logs and focus group interviews which revealed complementarities, as well as subtle differences between the two cases. The findings were summarized as learning dispositions; speaking fluency and confidence; learning diagnostics and completion deficiencies; task engagement, flow theory and higher order thinking skills; in addition to self efficacy and development of student identity. CLT has the potential to provide a more inclusive and dynamic education for diverse learners through vital outcomes and benefits which resonate with the real world.

(-)-CGP12177 increases contractile force through beta1l-adrenoceptors but not through beta3-adrenoceptors in human right atrial myocardium

(-)-CGP12177 is a non-conventional partial agonist that causes modest and transient increases of contractile force in human atrial trabeculae (Kaumann and Molenaar, 2008). These effects are markedly increased and maintained by inhibition of phosphodiesterase PDE3. As verified with recombinant receptors, the cardiostimulant effect of (-)-CGP12177 is mediated through a site at the beta1-adrenoceptor with lower affinity (beta1LAR) compared to the site through which (-)-CGP12177 antagonizes the effects of catecholamines (beta1HAR). However, in a recent report it was proposed that the positive inotropic effects of CGP12177 are mediated through beta3-adrenoceptors (Skeberdis et al 2008). We therefore investigated whether the effects of (-)-CGP12177 on human atrial trabeculae are antagonized by the beta3-adrenoceptor-selective antagonist L-748,337 (1 microM). (-)-CGP12177 (200 nM) caused a stable increase in force which was significantly reduced by the addition of (-)-bupranolol (1 microM), P = 0.002, (basal 4.45 ± 0.78 mN, IBMX (PDE inhibitor) 5.47 ± 1.01 mN, (-)-CGP12177 9.34 ± 1.33 mN, (-)-bupranolol 5.79 ± 1.08 mN, n = 6) but not affected by the addition of L-748,337 (1 microM), P = 0.12, (basal 4.48 ± 1.32 mN, IBMX 7.15 ± 2.28 mN, (-)-CGP12177 12.51 ± 3.71 mN, L-748,337 10.90 ± 3.49 mN, n = 6). Cumulative concentration-effect curves for (-)-CGP12177 were not shifted to the right by L-748,337 (1 microM). The –logEC50M values of (-)-CGP12177 in the absence and presence of L-748,337 were 7.21±0.09 and 7.41±0.13, respectively (data from 25 trabeculae from 8 patients, P=0.2) The positive inotropic effects of (-)-CGP12177 (IBMX present) were not antagonized by L-748,337 but were blunted by (-)-bupranolol (1 microM). The results rule out an involvement of beta3-adrenoceptors in the positive inotropic effects (-)-CGP12177 in human right atrial myocardium and are consistent with mediation through beta1LAR. Kaumann A and Molenaar P (2008) Pharmacol Ther 118, 303-336 Skeberdis VA et al (2008) J Clin Invest, 118, 3219-3227

Presentations in English : find your voice as a presenter

With estimates of more than thirty million given each day, presentations have become an integral part of modern society. They can signify the difference between gaining or losing a job, or being successful or unsuccessful at university and a future career. Presentations in English, combining a 128-page book and DVD, is an innovative and complete course aimed specifically at non-native speakers of English.

EAP essentials : a teacher's guide to principles and practice

Book review - Ancient scholars once journeyed across the Alps to study Italian law while some sailed the Mediterranean to learn Greek philosophy or examine Arabic scripts on science, medicine and mathematics. Devotees of philosophical and religious thought migrated to the Orient in search of transcendental wisdom. Today, the quest for knowledge has not changed as English-medium universities experience unprecedented internationalisation. This book is a publication for such a time as this. The authors invite readers to "join the tribe" (Becher, 1998) and learn the specific academic discourse and culture of English for Academic Purposes (EAP).

Distribution of forces during fulcrum bending radiographs on adolescent idiopathic scoliosis patients

At the Mater Children’s Hospital, approximately 80% of patients presenting with Adolescent Idiopathic Scoliosis requiring corrective surgery receive a fulcrum bending radiograph. The fulcrum bending radiograph provides a measurement of spine flexibility and a better indication of achievable surgical correction than lateral-bending radiographs (Cheung and Luk, 1997; Hay et al 2008). The magnitude and distribution of the corrective force exerted by the bolster on the patient’s body is unknown. The objective of this pilot study was to measure, for the first time, the forces transmitted to the patient’s ribs through the bolster during the fulcrum bending radiograph.

Ecology and bioprospecting

Bioprospecting is the exploration of biodiversity for new resources of social and commercial value. It is carried out by a wide range of established industries such as pharmaceuticals, manufacturing and agriculture as well as a wide range of comparatively new ones such as aquaculture, bioremediation, biomining, biomimetic engineering and nanotechnology. The benefits of bioprospecting have emerged from such a wide range of organisms and environments worldwide that it is not possible to predict what species or habitats will be critical to society, or industry, in the future. The benefits include an unexpected variety of products that include chemicals, genes, metabolic pathways, structures, materials and behaviours. These may provide physical blueprints or inspiration for new designs. Criticism aimed at bioprospecting has been addressed, in part, by international treaties and legal agreements aimed at stopping biopiracy and many activities are now funded by agencies that require capacity-building and economic benefits in host countries. Thus, much contemporary bioprospecting has multiple goals, including the conservation of biodiversity, the sustainable management of natural resources and economic development. Ecologists are involved in three vital ways: first, applying ecological principles to the discovery of new resources. In this context, natural history becomes a vast economic database. Second, carrying out field studies, most of them demographic, to help regulate the harvest of wild species. Third, emphasizing the profound importance of millions of mostly microscopic species to the global economy.

Contribution of transmembrane domain V amino acids to β1l-adrenoceptor activity and affinity

Introduction. There are two binding sites on the β1-adrenoceptor (AR), β1H and β1L corresponding to high and low affinity binding sites respectively, which can be activated to cause cardiostimulation. Some β-blockers that block β1AR and β2ARs can activate β1LARs at higher concentrations than those required to cause blockade. The β2AR does not form a corresponding low affinity binding site and therefore we postulated that heterologous amino acids are responsible for the formation of β1LAR. Aim. To investigate whether heterologous amino acids of transmembrane domain V (TMDV) of β1AR and β2ARs contribute to β1LAR. Methods. β1ARs, β2ARs and mutant β1ARs containing all (β1(β2TMDV)AR) or single amino acids of TMDV of the β2AR were prepared and stably expressed in Chinese Hamster Ovary cells. Concentration-effect curves for cyclicAMP accumulation were carried out for (-)-CGP12177 in the absence or presence of (-)-bupranolol. Results. The potencies (pEC50) of (-)-CGP12177 were β2AR (9.24 ± 0.14, n = 5), β1(V230I)AR (9.07 ± 0.07, n = 10), β1(β2TMDV)AR (8.86 ± 0.10, n = 15), β1(R222Q)AR (8.09 ± 0.29, n = 6), β1AR (8.00 ± 0.11, n = 11). The affinities (pKB) of (-)-bupranolol were β2AR (9.82 ± 0.52, n = 5), β1(V230I)AR (7.64 ± 0.12, n = 8), β1(β2TMV)AR (8.06 ± 0.17, n = 8), β1(R222Q)AR (7.33 ± 0.23, n = 5), β1AR (7.23 ± 0.23, n = 5). Discussion. The potency of (-)-CGP12177 was higher at β2AR than at β1AR consistent with activation through a low affinity site at the β1AR (β1LAR). The presence of V230 in β1AR accounted for the lower potency of (-)-CGP 12177. The affinity of (-)-bupranolol was lower at β1AR compared to β2AR. The presence of V230 in β1AR accounted in part for the lower affinity. In conclusion TMDV of the β1AR contributes in part to the low affinity binding site of β1AR.

Case study of collaborative learning in two contexts : what do students gain?

This book presents important research advances in the study of teaching and teacher research as well as a review of motivation in education; mentoring; an evaluation of online learning; educational change and computer-assisted teaching.