OBSERVATIONS OF BIRDS FEEDING ON THE FRUIT OF A SUCCESSIONAL TREE, TOPOBEA MULTIFLORA, IN SOUTHWESTERN COSTA RICA

Abstract ∙ We observed several individuals of a tropical fruiting tree, Topobea multiflora (Melastomataceae), to determine the diversity and prevalence of bird species that use this plant as a food source. Conducted on the south Pacific slope of Costa Rica, these observations are of interest because T. multiflora, though it grows in early successional habitat, attracts many bird species typically associated with mature forest. Most of these species are potential candidates for dispersing the small seeds of mature forest species as they leave the forest to feed on the fruit of T. multiflora. In this study, we recorded 477 observations of 24 species belonging to seven families feeding on T. multiflora fruit during ten count periods of observation. The family Thraupidae (tanagers) had both the highest proportion of feeding observations (65.8%) and the greatest diversity of all visiting taxa (13 species). The five species with the highest overall prevalence (prevalence >5%) were Silver‐throated Tanager (Tangara icterocephala), Cherrie’s Tanager (Ramphocelus costaricensis), Thick‐billed Euphonia (Euphonia laniirostris), Common Bush‐tanager (Chlorospingus ophthalmicus), and Bay‐headed Tanager (Tangara gyrola). Our results suggest that several species of Neotropical frugivores, because of their relationship to T. multiflora, may be considered indicator species of ongoing forest regeneration in southwestern Costa Rica. Resumen ∙ Observaciones de especies de aves alimentándose de frutos de Topobea multiflora en el sudoeste de Costa Rica Observamos varios ejemplares de árboles con frutos de la especie Topobea multiflora (Melastomataceae) para determinar la diversidad y prevalencia de las especies de aves que se alimentan de esta planta. Estas observaciones, realizadas en la pendiente sud‐Pacifica de Costa Rica, son de interés ya que T. multiflora, si bien crece en hábitats con disturbio o en regeneración, atrae muchas especies generalmente asociadas a bosques maduros. La mayoría de estas especies son candidatos potenciales para la dispersión de semillas de especies de plantas de bosques maduros cuando se alejan del bosque para alimentarse de los frutos de T. multiflora. En este estudio, registramos 477 observaciones de alimentación de frutos de T. multiflora, correspondientes a 24 especies pertenecientes a siete familias. La familia Thraupidae (tangaras) presento la mayor abundancia (341 observaciones) y la mayor riqueza de especies (13 especies). Las cinco especies con mayor prevalencia (> 5%) fueron: Tangara goliplateada (Tangara icterocephala), Tangara costarricense (Ramphocelus costaricensis), Eufonia piquigruesa (Euphonia laniirostris), Clorospingo común (Chlorospingus ophthalmicus) y Tangara cabecibaya (Tangara gyrola). Nuestros resultados sugieren que varias especies de aves frugívoras Neotropicales, debido a que frecuentan plantas de T. multiflora, podrían ser consideradas especies indicadoras de procesos de regeneración de bosques.

The Effect of Work-Study Methods Instruction on Student Achievement in Fifth Grade Social Studies

The problem with which this investigation is concerned is the effect of work-study method instruction upon the achievement of students in fifth grade social studies. The purpose of this investigation is to determine the effects of the SQ3R (Survey, Question, Read, Recite, Review) Study Method instruction upon the achievement of students in fifth grade social studies. The subjects ranged in age from ten years two months to thirteen years three months. Th I.Q. for the subjects ranged from 70 to 135. Of the 102 subjects involved in the study, 42 were male and 60 were female. The I.Q. score from the California Test of Mental Maturity, S Form was used to structure the subjects into three intelligence levels. Fifty-four subjects served as the experimental group, and forty-eight served as the control group. The instrument used to obtain pretest and posttest scores on the variable relating to achievement was the SRA Assessment Survey, Blue Level. Form E was used for the pretest, and Form F was used for the posttest. The subjects were assigned to four classes which were near equal. Two classes were selected by the principal to serve as the experimental group. The other two classes served as the control group. The investigator spent equal time with the control and the experimental group. The four classroom teachers rotated between experimental and control groups on an equal basis. Students in the experimental group met nineteen times during the study for a thirty-minute period. During these sessions, the experimental subjects used the SQ3R Study Method to do social studies assignments. The control group met for the same number of sessions and for an equal amount of time. They worked with the same content but without using the SQ3R Study Method. The analysis of covariance was employed with pretest scores as the covariant

Transversality of Electromagnetic Waves in the Calculus-Based Introductory Physics Course

Introductory calculus-based physics textbooks state that electromagnetic waves are transverse and list many of their properties, but most such textbooks do not bring forth arguments why this is so. Both physical and theoretical arguments are at a level appropriate for students of courses based on such books, and could be readily used by instructors of such courses. Here, we discuss two physical arguments (based on polarization experiments and on lack of monopole electromagnetic radiation), and the full argument for the transversality of (plane) electromagnetic waves based on the integral Maxwell equations. We also show, at a level appropriate for the introductory course, why the electric and magnetic fields in a wave are in phase and the relation of their magnitudes.Comment: 10 pages, 6 figure

Photorespiration: metabolic pathways and their role in stress protection

Photorespiration results from the oxygenase reaction catalysed by ribulose-1,5-bisphosphate carboxylase/ oxygenase. In this reaction glycollate-2-phosphate is produced and subsequently metabolized in the photorespiratory pathway to form the Calvin cycle intermediate glycerate-3-phosphate. During this metabolic process, CO2 and NH3 are produced and ATP and reducing equivalents are consumed, thus making photorespiration a wasteful process. However, precisely because of this ine¤ciency, photorespiration could serve as an energy sink preventing the overreduction of the photosynthetic electron transport chain and photoinhibition, especially under stress conditions that lead to reduced rates of photosynthetic CO2 assimilation. Furthermore, photorespiration provides metabolites for other metabolic processes, e.g. glycine for the synthesis of glutathione, which is also involved in stress protection. In this review, we describe the use of photorespiratory mutants to study the control and regulation of photorespiratory pathways. In addition, we discuss the possible role of photorespiration under stress conditions, such as drought, high salt concentrations and high light intensities encountered by alpine plants

Characteristics of C-4 photosynthesis in stems and petioles of C-3 flowering plants

Most plants are known as C-3 plants because the first product of photosynthetic CO2 fixation is a three-carbon compound. C-4 plants, which use an alternative pathway in which the first product is a four-carbon compound, have evolved independently many times and are found in at least 18 families. In addition to differences in their biochemistry, photosynthetic organs of C-4 plants show alterations in their anatomy and ultrastructure. Little is known about whether the biochemical or anatomical characteristics of C-4 photosynthesis evolved first. Here we report that tobacco, a typical C-3 plant, shows characteristics of C-4 photosynthesis in cells of stems and petioles that surround the xylem and phloem, and that these cells are supplied with carbon for photosynthesis from the vascular system and not from stomata. These photosynthetic cells possess high activities of enzymes characteristic of C-4 photosynthesis, which allow the decarboxylation of four-carbon organic acids from the xylem and phloem, thus releasing CO2 for photosynthesis. These biochemical characteristics of C-4 photosynthesis in cells around the vascular bundles of stems of C-3 plants might explain why C-4 photosynthesis has evolved independently many times

Behind the silence of harmony: risk factors for physical and sexual violence among women in rural Indonesia

BACKGROUND: Indonesia has the fourth largest population in the world. Few studies have identified the risk factors of Indonesian women for domestic violence. Such research will be useful for the development of prevention programs aiming at reducing domestic violence. Our study examines associations between physical and sexual violence among rural Javanese Indonesian women and sociodemographic factors, husband's psychosocial and behavioral characteristics and attitudes toward violence and gender roles. METHODS: A cohort of pregnant women within the Demographic Surveillance Site (DSS) in Purworejo district, Central Java, Indonesia, was enrolled in a longitudinal study between 1996 and 1998. In the following year (1999), a cross-sectional domestic violence household survey was conducted with 765 consenting women from that cohort. Female field workers, trained using the WHO Multi-Country study instrument on domestic violence, conducted interviews. Crude and adjusted odds ratios at 95% CI were applied for analysis. RESULTS: Lifetime exposure to sexual and physical violence was 22% and 11%. Sexual violence was associated with husbands' demographic characteristics (less than 35 years and educated less than 9 years) and women's economic independence. Exposure to physical violence among a small group of women (2-6%) was strongly associated with husbands' personal characteristics; being unfaithful, using alcohol, fighting with other men and having witnessed domestic violence as a child. The attitudes and norms expressed by the women confirm that unequal gender relationships are more common among women living in the highlands and being married to poorly educated men. Slightly more than half of the women (59%) considered it justifiable to refuse coercive sex. This attitude was also more common among financially independent women (71%), who also had a higher risk of exposure to sexual violence. CONCLUSIONS: Women who did not support the right of women to refuse sex were more likely to experience physical violence, while those who justified hitting for some reasons were more likely to experience sexual violence. Our study suggests that Javanese women live in a high degree of gender-based subordination within marriage relationships, maintained and reinforced through physical and sexual violence. Our findings indicate that women's risk of physical and sexual violence is related to traditional gender norms

Silicate weathering and carbon cycle controls on the Oligocene-Miocene transition glaciation

Changes in both silicate weathering rates and organic carbon burial have been proposed as drivers of the transient “Mi-1” glaciation event at the Oligocene-Miocene transition (OMT; ~23 Ma). However detailed geochemical proxy data are required to test these hypotheses. Here we present records of Li/Ca, Mg/Ca, Cd/Ca, U/Ca, δ18O, δ13C, and shell weight in planktonic foraminifera from marine sediments spanning the OMT in the equatorial Atlantic Ocean. Li/Ca values increase by 1 μmol/mol across this interval. We interpret this to indicate a ~20% increase in silicate weathering rates, which would have lowered atmospheric CO2, potentially forcing the Antarctic glaciation circa 23 Ma. δ13C of thermocline dwelling planktonic foraminifera track the global increase in seawater δ13C across the OMT and during the Mi-1 event, hence supporting a hypothesized global increase in organic carbon burial rates. High δ13C previously measured in epipelagic planktonic foraminifera and high Cd/Ca ratios during Mi-1 are interpreted to represent locally enhanced primary productivity, stimulated by increased nutrients supply to surface waters. The fingerprint of high export production and associated organic carbon burial at this site is found in reduced bottom water oxygenation (inferred from high foraminiferal U/Ca), and enhanced respiratory dissolution of carbonates, characterised by reduced foraminiferal shell weight. Replication of our results elsewhere would strengthen the case that weathering-induced CO2 sequestration preconditioned climate for Antarctic ice sheet growth across the OMT and increased burial of organic carbon acted as a feedback that intensified cooling at this time