The life cycle of Hydroperla crosbyi (Plecoptera: Perlodidae)

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Hydroperla crosbyi in Texas exhibited a univoltine, fast life cycle over the three - year study period. Adults emerged in February – March when mean daily stream temperature reached ca. 15 C. Reared females in the lab deposited up to three egg masses. Mean fecundity of dissected females was 787 eggs/female. Oviposition in the field was observed and described. Eggs were triangular in cross section, brown, and measured 400 µ m × 535 µ m. They underwent an ca. seven-month diapause until mean daily stream temperature decreased to 18 C. Eyespots appeared, and hatching followed in two to three weeks. First instar nymphs were measured and described. Male and female nymphs underwent 12 and 14 instars, respectively, and could be sexed by the sixth. Fast growth occurred in the coldest season and Simuliidae and Chironomidae larvae were preferred food throughout development. Eggs contained a mean of 6.21 cal/mg. Ash - free mean caloric value of last instar nymphs was 6.0 cal/mg. Adult males and females lost 33.8 percent and 57.6 percent, respectively, of their caloric pool through their ca. 12 days of life.        

'Science Fights Death': David Stark Murray,Science, and Socialism in Interwar Britain

The pathologist David Stark Murray (1900-77) was a founder and leading member of the Socialist Medical Association (SMA), an organization affiliated to the Labour Party and instrumental in shaping its health policy in the period up to 1945. Murray played a prominent role in the SMA as a member of its Executive Committee and as Editor of its journal MedicineToday and Tomorrow. This article examines Murray's popular writings about science during the interwar period, focusing on his emphasis on the relationship between, on the one hand, scientific knowledge and scientific method; and, on the other, a socialized health service and a socialist society.     

Leibniz on Hobbes’s materialism

This paper discusses Leibniz’s interpretation and criticism of Hobbesian materialism in the period 1698-1705. Leibniz had continued to be interested in Hobbes’s work, despite not engaging with it as intensively as he did earlier (around 1670). Leibniz offers an interpretation of Hobbes that explains Hobbes’s materialism as derived from his imagistic theory of ideas. Leibniz then criticizes Hobbes’s view as being based on a faulty theory of ideas, and as having problematic consequences, particularly with regard to what one says about God. Some of this criticism is found in the New essays, but equally significant is Leibniz’s correspondence with Damaris Masham, who proposed an argument for materialism very much like that which Leibniz attributed to Hobbes. The paper concludes by discussing the suggestion that Leibniz at this time, particularly in the New essays, himself adopted Hobbesian ideas. Though Leibniz did use some of Hobbes’s examples, and did think at this time that all souls were associated with bodies, the resulting position is still rather distant from Hobbesian materialism.     

Muscle fluorometry: a determination of the depth of penetration

Fluorometric recordings of NADH (nicotinamide adenine dinucleotide) were made on rabbit papillary muscles. The specimens were placed between the UV light source and a small window of the detection stage. As the muscle was moved over the window in a transverse direction, simultaneous measurements could be taken of transmitted UV light and fluorescent light for various thicknesses of tissue. It is concluded that a muscle thickness of 0.65 mm is optimal before absorption of the incident light decreases the fluorescence signal.     

Electrical membrane constants of sartorius muscle fibers from the South American froǵ,Leptodactylus ocellatus

Résumé Les constantes électriques de la membrane du m. sartorius, de la grenouille sudaméricaine,Leptodactylus ocellatus, ont été mesurées. Les résultats pour les cellules, dans du Ringer normal (2.5 mM potassium), s'accordent avec ceux deHubbard pourRana temporaria. En 2.5 mM cesium Ringer, une diminution de diamètre de 12% et une augmentation de 16% de la capacité de la membrane ont été observées.

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This work was supported in part by the US Navy department (offfice of Navy research), the US Automic Energy Commission, and the Direction General de Investtgations y Desarrollo, Ministerio de Defensa National Argentina.