Fishes of Crowley\u27s Ridge in Arkansas

Crowley\u27s Ridge is one of the six natural geographic divisions of Arkansas which rises out of the Mississippi embayment as a relatively steep, uncultivated loessial mass. The ridge is drained by a network of headwater streams which are relatively clear with alkaline pH values and uniformly low alkalinity values. Carbon dioxide values were moderate and oxygen values were adequate. The fish species collected were basically headwater in composition. Isolated groups of characteristically upland species indicate that environmental quality of adjacent deltaic streams was better at one time

Fermentation Utilization of Cassava. The Butyl-Acetonic Fermentation

The cassava plant belongs to the family Euphorbiaccaee and is botanically known as Manihot utilissima Pohl. It is also called tapioca or manioc although the word tapioca is often used to designate certain forms of cassava products. The cassava is a plant possessing quite unusual characteristics. It has no known pests nor enemies. It grows in most soils, resists extreme droughts, and propagates easily although its growth is restricted to tropical regions. The plant itself is a perennial shrub which attains a height of six to twelve feet at the age of one year. At the base of its stem it produces a cluster of long fleshy roots. The starch content of the fresh cassava root is 25 to 30 per cent; these roots furnish the cheapest source of starch known

Relation of the Structure of Sugars to Their Dissimilation in the Butyl-Acetonic Fermentation

The dissimilation of starch in corn mash by Clostridium acetobutylicum produces butanol, acetone and ethanol, commonly called solvents \u27, in the approximate ratio of 60:80:10, respectively. Although corn mash is the usual substrate, fermentations of certain pure carbohydrates by Cl. acetobutylicum have been investigated previously to some extent. The studies of various workers (3, 4, 5, 6, 9, 10, 11, 12) have shown that a considerable number of sugars are fermented by the butyl organism in semi-synthetic media. The sugar fermentations are somewhat slower than for corn mash, and the final acidities arc somewhat higher with yields of neutral products correspondingly lower. There is some variation in the proportion of solvents produced from the various carbohydrates. Hence, an attempt was made in this investigation to relate the structure of the sugars and the proportions of the solvents formed, by subjecting to the action of the butyl-acetone organism as many of the sugars and polyhydric alcohols as could be readily obtained or prepared. These included thirteen compounds which had not been previously studied in detail, with dextrose and corn mash used for controls

The Effect of Steffen Waste on the Fermentation of Pentosans from the Corn Stalk

It was found that Steffen waste furnishes a suitable source of nitrogen, salts, and buffers for the growth of Aerobacter pectinovorum on pentosan material prepared from corn-stalks

Numbers are Just Not Enough: A Critical Analysis of Race, Gender, and Sexuality in Elementary and Middle School Health Textbooks

Textbooks are a multimillion dollar publishing business in the United States. Even as 21st-century classrooms become more multimodal, digital and hardcopy textbooks remain a key feature of American education. Consequently, classroom textbooks have been shown to control knowledge dissemination across the content areas. In particular, health texts have been uniquely shown to communicate values that validate or marginalize students and encourage healthy or harmful activity. Thus,what textbook makers choose to include as worthy of study, and how they portray various groups of people with regard to race, gender, and sexuality has societal implications. Employing quantitative and qualitative content analysis methods, we analyzed 1,468 images across elementary and middle school health textbooks to examine the portrayal of race, gender, and sexuality.We found that, although gender and racial diversity are well-represented in texts, women and people of color were frequently portrayed in stereotypical roles. For example, girls were depicted daydreaming about heterosexual marriage. Furthermore, this analysis revealed limited representations of sexuality. Findings suggest that focusing on the numerical representation of marginalized groups is not enough to address issues of equity and power in classroom curricula. Instead,we argue, educators must consider the ways in which people are positioned in curricular materials, and ask if portrayals perpetuate or challenge traditional stereotypes

Middle school student attitudes toward science, and their relationships with instructional practices: a survey of Chinese students’ preferred versus actual instruction

This study explored relationships between students\u27 attitudes toward science and their preferred versus actual experience of cooperative, constructivist-oriented, or direct instruction. The sample consisted of 1334 Chinese middle school students in physics and chemistry classrooms. Results showed that students report experiencing more direct instruction, very little constructivist-oriented instruction, and a moderate amount of cooperative instruction. Attitudes toward science were positively related to cooperative teaching strategies like group work in class or developing small-group projects. There was no significant effect of constructivist-oriented instruction or of direct instruction on students\u27 attitudes. Whereas previous studies demonstrated positive impacts of constructivist teaching on student understanding of science concepts, student attitude toward school science appears to be more related to social interaction or cooperation. Lack of any statistically significant differential effect from constructivist-oriented instruction might also be related to the overall low incidence of such instruction experienced by our sample

Cervical Vascular and Upper Airway Asymmetry in Velo-Cardio-Facial Syndrome: Correlation of Nasopharyngoscopy With MRA

Purpose Velo-cardio-facial syndrome (VCFS), the most common genetic syndrome causing cleft palate, is associated with internal carotid and vertebral artery anomalies, as well as upper airway asymmetry. Medially displaced internal carotid arteries, often immediately submucosal, present a risk of vascular injury during pharyngeal flap surgery for velopharyngeal insufficiency (VPI). We evaluate the frequency and spectrum of cervical vascular anomalies in a large cohort of VCFS patients correlating MRA with nasopharyngolaryngoscopy in detecting at risk carotid arteries. Furthermore, we assess the relationship with respect to laterality between cervical vascular patterns and the asymmetric abnormalities of these subjects’ upper airways. Methods Cervical MRAs of 86 subjects with VCFS and 50 control subjects were independently reviewed by three neuroradiologists. The course of the internal carotid and vertebral arteries was identified within the pharyngeal soft tissues. Medial deviation, level of bifurcation, dominance, anomalous origin, and vessel tortuosity were recorded. Nasopharyngoscopy examinations were available for retrospective review in 43 patients and were assessed for palatal and posterior pharyngeal wall symmetry, true vocal cord motion and size, and for the presence or absence of carotid pulsations. The endoscopic findings were compared with MRA results. Results Of the 86 subjects, 80 (93%) had one or more vascular anomalies. 42 subjects (49%) were found to have medial deviation of at least one internal carotid artery. In 24 subjects (28%) the anomalous internal carotid artery was directly submucosal; four of these were bilateral (5% of the total sample, 17% of those with a submucosal internal carotid). Other carotid anomalies included low carotid bifurcation (44 subjects or 51%), anomalous origin of the right common carotid (32 cases, or 37%), and two cases of internal carotid agenesis/hypoplasia. Vertebral artery anomalies included vessel tortuosity (34 cases, or 40%), hypoplasia (10 cases, or 12%), looping (4 cases, or 5%), and one case of a double left vertebral artery. Though patients in our study showed an asymmetric distribution of vascular anomalies, no association was found between the laterality of palatal motion, pharyngeal fullness, or laryngeal movement and structure with ipsilateral vertebral or carotid artery anomalies. Of the 33 pulsatile carotid arteries visualized at nasopharyngoscopy, only nine were found to be submucosal on MRA. In contrast, 11 submucosal carotid arteries confirmed at MRA demonstrated no visible pulsations. Positive and negative predictive values of pulsative arteries seen endoscopically for MRA confirmation of a submucosal carotid course was 27% and 79% respectively. Conclusions Carotid and vertebral artery anomalies are common in VCFS including marked medial deviation of the internal carotid artery in close proximity to the donor site for pharyngeal flap surgery. Lack of correlation between laterality of vascular anomalies and upper airway structural asymmetry in VCFS does not support the hypothesis that palatal, pharyngeal, and laryngeal anomalies are due to secondary developmental sequences caused by in utero vascular insufficiency. The presence or absence of carotid pulsations seen by nasopharyngoscopy does not correlate with the carotid arterial depth identified on MRA. Furthermore, identification of the relative medial–lateral retropharyngeal position of a submucosal carotid affords the opportunity to modify the surgical approach. These findings further support the routine use of pre-operative neck MRA in VCFS patients in surgical planning

Testing massive star evolution, star-formation history and feedback at low metallicity : Spectroscopic analysis of OB stars in the SMC Wing

Stars which start their lives with spectral types O and early-B are the progenitors of core-collapse supernovae, long gamma-ray bursts, neutron stars, and black holes. These massive stars are the primary sources of stellar feedback in star-forming galaxies. At low metallicities, the properties of massive stars and their evolution are not yet fully explored. Here we report a spectroscopic study of 320 OB stars in the Small Magellanic Cloud. The data, which we obtained with the ESO Very Large Telescope, were analyzed using state-of-the-art stellar atmosphere models. We find that stellar winds of our sample stars are much weaker than theoretically expected. The stellar rotation rates show a bi-modal distribution. The well-populated upper Hertzsprung-Russell diagram including our sample OB stars from SMC Wing as well as additional evolved stars all over SMC from the literature shows a strict luminosity limit. The comparison with single-star evolutionary tracks suggests a dichotomy in the fate of massive stars in the SMC. Only stars with Minit<30M$_{\odot}$ seem to evolve from the main sequence to the cool side of the HRD to become a red supergiant and to explode as type II-P supernova. In contrast, stars with Minit>30M$_{\odot}$ appear to stay always hot and might evolve quasi chemically homogeneously, finally collapsing to relatively massive black holes. However, we find no indication that chemical mixing is correlated with rapid rotation. We report extended star-formation episodes in a quiescent low-density region of the Wing, which is progressing stochastically. We measure the key parameters of stellar feedback and establish the links between the rates of star formation and supernovae. Our study reveals that in metal-poor environments the stellar feedback is dominated by core-collapse supernovae in combination with winds and ionizing radiation supplied by a few of the most massive stars.Comment: Accepted for publication in Astronomy & Astrophysic