Observed and Calculated Values of the Magnetic Intensity over a Major Geologic Structure

The authors compare the observed and calculated values of the vertical and horizontal components of the magnetic field along a profile across the Los Angles Basin. A structural geologic cross section compiled from seismic, gravity and geologic data was used as a basis for calculating the magnetic field. In the San Pedro Hills portion of the cross section the calculated and observed values disagree, indicating that the granitic basement rocks lie at greater depths then shown in the structure section

Tendencias actuales en los algodones de planchado permanente.

La introducción en 1964 de prendas de planchado permanente en Estados Unidos tuvo un impacto que puede compararse por su importancia con el de la introducción del nylon. El empleo de tejidos de algodón 100 % para planchado permanente ha disminuído debido a un problema de abrasión debido principalmente a las duras condiciones del tratamiento químico. Se describen métodos que aumentan la resistencia a la abrasión de los tejidos de algodón 100 %. Estos métodos incluyen la adición de determinados polímeros y suavizantes, mercerizado sin tensión del tejido antes de la reticulación, y el empleo de adecuadas condiciones de polimerización así como de un hilo o tejidos de alta resistencia. Igualmente, se describen otros métodos tales como reticulado optativo, doble polimerización y fijado en húmedo. En todos estos procesos la elección adecuada del agente reticulador es muy importante. Estos resultados demuestran que pueden producirse mejores algodones 100% para planchado permanente mediante cierto número de procesos nuevos.Peer Reviewe

Functional consequences of the asymmetric architecture of the ctenophore statocyst

Author Posting. © Marine Biological Laboratory, 2015. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 229 (2015): 173-184.Ctenophores, or comb jellies, are geotactic with a statocyst that controls the activity of the eight ciliary comb rows. If a ctenophore is tilted or displaced from a position of vertical balance, it rights itself by asymmetric frequencies of beating on the uppermost and lowermost comb rows, turning to swim up or down depending on its mood. I recently discovered that the statocyst of ctenophores has an asymmetric architecture related to the sagittal and tentacular planes along the oral-aboral axis. The four groups of pacemaker balancer cilia are arranged in a rectangle along the tentacular plane, and support a superellipsoidal statolith elongated in the tentacular plane. By controlled tilting of immobilized ctenophores in either body plane with video recording of activated comb rows, I found that higher beat frequencies occurred in the sagittal than in the tentacular plane at orthogonal orientations. Similar tilting experiments on isolated statocyst slices showed that statolith displacement due to gravity and the resulting deflection of the mechanoresponsive balancers are greater in the sagittal plane. Finally, tilting experiments on a mechanical model gave results similar to those of real statocysts, indicating that the geometric asymmetries of statolith design are sufficient to account for my findings. The asymmetric architecture of the ctenophore statocyst thus has functional consequences, but a possible adaptive value is not known

Formation of the statolith in the ctenophore Mnemiopsis leidyi

Author Posting. © Marine Biological Laboratory, 2014. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 227 (2014): 7-18.The aboral sensory organ (apical organ) of ctenophores contains a statocyst with a single large statolith. The statolith comprises living cells (lithocytes), each containing a large membrane-bound concretion. The statolith is supported on the distal ends of four compound motile mechanoresponsive cilia (balancers) which control the beat frequencies of the eight locomotory comb rows, and thereby the orientation of animals to gravity. In Mnemiopsis leidyi and Pleurobrachia pileus, lithocytes arise in the thickened epithelial floor of the apical organ on opposite sides along the tentacular plane. Lithocytes progressively differentiate and migrate toward the apical surface where they bud off next to the bases of the balancers. New lithocytes are transported up the balancers by ciliary surface motility to form the statolith (Noda, 2013). The statolith has a superellipsoidal shape due to the rectangular arrangement of the four balancers and the addition of new lithocytes to its ends via the balancers. The size of the statolith increases with animal size, starting at the highest rate of growth in younger stages and gradually decreasing in larger animals. The total number of developing lithocytes in the epithelial floor increases rapidly in smaller animals and reaches a plateau range in larger animals. Lithocytes are therefore produced continually throughout life for enlargement of the statolith and possibly for turnover and replacement of existing lithocytes. The dome cilia enclosing the statocyst were observed to propagate slow, low-ampitude waves distally. The dome cilia may act as an undulating screen to prevent foreign objects in the seawater from being transported non-specifically up the balancers to make a defective statolith