Stylolites: characteristics and origin

Stylolites are alternating interpenetrating columns of stone that form irregular interlocking partings or sutures in rock strata. They are most common along bedding planes of limestone but some are oblique or even perpendicular to bedding . Although the vast majority of stylolites occur in calcareous rocks, stylolites have been found in sandstone, quartzite and gypsum. The word "stylolite" refers to each individual column of stone. Across section of a group of stylolites parallel to their length presents a rough, jagged line called a "stylolite seam" that resembles the sutures of a human skull. Stylolites always have a dark colored "clay" cap at the ends of the columns. The sides of the columns are typically discolored with a thin film of clay and show parallel flutings or striations that parallel their length. The shapes of individual stylolites vary greatly from broad flat-topped columns to pointed, jagged and tapering forms. After much controversy concerning the origin of stylolites, it is generally believed that they form by a process of chemical solution under pressure in lithified rock along some crack or seam. The interteething is produced because of differential solubilities and pressures within the rock unit. The clay cap on the stylolites is the non-soluble residue of the dissolved rock. Stylolites are only one of the possible end products in the spectrum of limestone responses to stress. They form in limestone units that have structural resistance to stress and contain relatively little clay or silt. Stylolites may play a major role in initiating or preserving oil accumulations in limestone. Where they are formed due to tectonic compression, stylolites may be useful in providing information on paleo-stress patterns.No embarg

Comparable rest-related promotion of spatial memory consolidation in younger and older adults

Flexible spatial navigation depends on cognitive mapping, a function that declines with increasing age. In young adults, a brief period of postnavigation rest promotes the consolidation and integration of spatial memories into accurate cognitive maps. We examined (1) whether rest promotes spatial memory consolidation and integration in older adults; and (2) whether the magnitude of the rest benefit changes with increasing age. Young and older adults learned a route through a virtual environment, followed by a 10-minute delay comprising either wakeful rest or a perceptual task, and a subsequent cognitive mapping task, requiring the pointing to landmarks from different locations. Pointing accuracy was lower in the older than younger adults. However, there was a comparable rest-related enhancement in pointing accuracy in the 2 age groups. Together our findings suggest that (1) the age-related decline in cognitive mapping cannot be explained by increased consolidation interference in older adults; and (2) as we grow older, rest continues to support the consolidation and integration of spatial memories

Stakeholder perspectives on implementing the National Cancer Institute’s patient-reported outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE)

The National Cancer Institute (NCI) is developing a patient-reported version of its Common Terminology Criteria for Adverse Events, called the "PRO-CTCAE." The PRO-CTCAE consists of a library of patient-reported items which can be administered in clinical trials to directly capture the patient experience of adverse events during cancer treatment, as well as a software platform for administering these items via computer or telephone. In order to better understand the impressions of stakeholders involved in cancer clinical research about the potential value of the PRO-CTCAE approach to capturing adverse event information in clinical research, as well as their perspectives about barriers and strategies for implementing the PRO-CTCAE in NCI-sponsored cancer trials, a survey was conducted. A survey including structured and open-ended questions was developed to elicit perceptions about the use of patient-reported outcomes (PROs) for adverse event reporting, and to explore logistical considerations for implementing the PRO-CTCAE in cancer trials. The survey was distributed electronically and by paper to a convenience sample of leadership and committee members in the NCI's cooperative group network, including principal investigators, clinical investigators, research nurses, data managers, patient advocates, and representatives of the NCI and Food and Drug Administration. Between October, 2008 through February, 2009, 727 surveys were collected. Most respondents (93%) agreed that patient reporting of adverse symptoms would be useful for improving understanding of the patient experience with treatment in cancer trials, and 88%, 80%, and 76%, respectively, endorsed that administration of PRO-CTCAE items in clinical trials would improve the completeness, accuracy, and efficiency of symptom data collection. More than three fourths believed that patient reports would be useful for informing treatment dose modifications and towards FDA regulatory evaluation of drugs. Eighty-eight percent felt that patients in clinical trials would be willing to self-report adverse symptoms at clinic visits via computer, and 68% felt patients would self-report weekly from home via the internet or an automated telephone system. Lack of computers and limited space and personnel were seen as potential barriers to in-clinic self-reporting, but these were judged to be surmountable with adequate funding. The PRO-CTCAE items and software are viewed by a majority of survey respondents as a means to improve adverse event data quality and comprehensiveness, enhance clinical decision-making, and foster patient-clinician communication. Research is ongoing to assess the measurement properties and feasibility of implementing this measure in cancer clinical trials