1,471 research outputs found
Quasi-static evolution for fatigue debonding
The propagation of fractures in a solid undergoing cyclic loadings
is known as the fatigue phenomenon. In this paper, we present a time continuous
model for fatigue, in the special situation of the debonding of thin layers,
coming from a time discretized version recently proposed by
Jaubert and Marigo [C. R. Mecanique 333 (2005) 550–556].
Under very general assumptions on the surface energy density and
on the applied displacement, we discuss the well-posedness of our
problem and we give the main properties of the evolution process
Recommended from our members
Hypoxia-inducible factor: role in cell survival in superoxide dismutase overexpressing mice after neonatal hypoxia-ischemia.
BackgroundSixty percent of infants with severe neonatal hypoxic-ischemic encephalopathy die, while most survivors have permanent disabilities. Treatment for neonatal hypoxic-ischemic encephalopathy is limited to therapeutic hypothermia, but it does not offer complete protection. Here, we investigated whether hypoxia-inducible factor (HIF) promotes cell survival and suggested neuroprotective strategies.PurposeHIF-1α-deficient mice have increased brain injury after neonatal hypoxia-ischemia (HI), and the role of HIF-2α in HI is not well characterized. Copper-zinc superoxide dismutase (SOD)1 overexpression is not beneficial in neonatal HI. The expression of HIF-1α and HIF-2α was measured in SOD1 overexpressing mice and compared to wild-type littermates to see if alteration in expression explains this lack of benefit.MethodsOn postnatal day 9, C57Bl/6 mice were subjected to HI, and protein expression was measured by western blotting in the ipsilateral cortex of wild-type and SOD1 overexpressing mice to quantify HIF-1α and HIF-2α. Spectrin expression was also measured to characterize the mechanism of cell death.ResultsHIF-1α protein expression did not significantly change after HI injury in the SOD1-overexpressing or wild-type mouse cortex. However, HIF-2α protein expression increased 30 minutes after HI injury in the wild-type and SOD1-overexpressing mouse cortex and decreased to baseline value at 24 hours after HI injury. Spectrin 145/150 expression did not significantly change after HI injury in the SOD1- overexpressing or wild-type mouse cortex. However, spectrin 120 expression increased in both wild-type and SOD1-overexpressing mouse at 4 hours after HI, which decreased by 24 hours, indicating a greater role of apoptotic cell death.ConclusionHIF-1α and HIF-2α may promote cell survival in neonatal HI in a cell-specific and regional fashion. Our findings suggest that early HIF-2α upregulation precedes apoptotic cell death and limits necrotic cell death. However, the influence of SOD was not clarified; it remains an intriguing factor in neonatal HI
Recommended from our members
Outreach practices of a small college counseling center: A comprehensive model to serve the college community
Over the past 10 years college counseling centers (CCCs) have been urged to broaden their focus considerably and to serve the entire campus community due to increases in student mental health issues. Engaging in outreach efforts is one way to address campus wide needs. However, few research efforts have been conducted to systematically investigate how outreach is practiced at a small college. The dialogue around outreach has focused on single programs at large institutions rather than the network of interventions that occur on a campus. The purpose of this study is to understand the web of relationships between a counseling center and the college community. This qualitative case study describes the various outreach activities of a small college counseling center from the perspective of the counseling center staff and members of the college community. Using ethnographic tools (i.e., semi-structured interviews, focus group, and context analysis), this study describes the different systems the counseling center navigates to serve the college campus. The study identifies how members of a counseling center develop a shared pattern of outreach behavior. This study adds to the literature in several ways: it increases our understanding of how a small college counseling center supports the campus community and provides a model or framework for how outreach is performed on a smaller campus
Guidance on Presidential Records by the National Archives and Records Administration
How the Presidential Records Act Affects the President, Vice President, and White House Staff During the Administration
Overview
The Presidential Records Act (PRA) of 1978, as amended, 44 U.S.C. §§ 2201-2209, governs the official records of Presidents and Vice Presidents created on or received after January 20, 1981. The PRA changed the legal ownership of the official records of the President from private to public.
The PRA established a new statutory structure under which Presidents must manage their records. The Presidential Records Act:
Defines and states public ownership of the records;
Places the responsibility for the custody and management of incumbent Presidential records with the President;
Allows the incumbent President to dispose of records that no longer have administrative, historical, informational, or evidentiary value, once the Archivist of the United States has provided his written views on the proposed disposal;
Requires that the President and the President\u27s staff take all practical steps to file personal records separately from Presidential records;
Establishes a process for public access to and restriction of Presidential records. Specifically, the PRA allows for public access to Presidential records, including through the Freedom of Information Act (FOIA), beginning five years after the end of the Administration, but allows the President to invoke as many as six specific restrictions to public access for up to twelve years. The PRA also establishes procedures for Congress, courts, and subsequent Administrations to obtain “special” access to records that remain closed to the public. (A chart describing these access provisions and restrictions is attached.) The procedures for privilege review by the incumbent and former Presidents are established by the PRA, Executive order 13489 and NARA’s regulations;
Requires that Vice Presidential records are to be treated in the same way as Presidential records.
Presidential records are defined as:
“documentary materials, or any reasonably segregable portion thereof, created or received by the President, the President’s immediate staff, or a unit or individual of the Executive Office of the President whose function is to advise and assist the President, in the course of conducting activities which relate to or have an effect upon the carrying out of the constitutional, statutory, or other official or ceremonial duties of the President.” [44 U.S.C. § 2201(2)].
These records can be in any media, including textual, audiovisual, and electronic.
Personal records are defined as:
“documentary materials or any reasonably segregable portion thereof, of a purely private or nonpublic character, which do not relate to or have an effect upon the carrying out of the constitutional, statutory, or other official or ceremonial duties of the President” and which include “diaries, journals, or other personal notes serving as the functional equivalent of a diary or journal which are not prepared or utilized for, or circulated or communicated in the course of, transacting Government business,” “private political associations” and “materials relating exclusively to the President’s own election to the office of the Presidency” [44 U.S.C. § 2201(3)].
Personal records remain the personal property of the President or the record creator.
Records created by the President-elect and the transition team are also considered personal records. To the extent that these records are received and used after the inauguration by the incoming Presidential Administration, they may become Presidential or Federal records. Former Presidents have traditionally donated these personal transition records to the National Archives and Records Administration for deposit in their Presidential Library
- …