15 research outputs found
Mesocrystalline Architecture in Hyaline Foraminifer Shells Indicates a NonâClassical Crystallisation Pathway
Calcareous foraminifer shells (tests) represent one of the most important archives for paleoenvironmental and paleoclimatic reconstruction. To develop a mechanistic understanding of the relationship between environmental parameters and proxy signals, knowledge of the fundamental processes operating during foraminiferal biomineralization is essential. Here, we apply microscopic and diffractionâbased methods to address the crystallographic and hierarchical structure of the test wall of different hyaline foraminifer species. Our results show that the tests are constructed from micrometerâscale oriented mesocrystals built of nanometerâscale entities. Based on these observations, we propose a mechanistic extension to the biomineralization model for hyaline foraminifers, centered on the formation and assembly of units of metastable carbonate phases to the final mesocrystal via a nonâclassical particle attachment process, possibly facilitated by organic matter. This implies the presence of metastable precursors such as vaterite or amorphous calcium carbonate, along with phase transitions to calcite, which is relevant for the mechanistic understanding of proxy incorporation in the hyaline foraminifers.Plain Language Summary:
Foraminifers are single celled marine organisms typically half a millimeter in size, which form shells made of calcium carbonate. During their life, the chemical composition of their shells records environmental conditions. By analyzing fossil shells, past conditions can be reconstructed to understand ancient oceans and climate change. To do that correctly, we need to know exactly how foraminifers form their shell. We find that foraminifers build micrometerâsized mesocrystals which are made of smaller building blocks. This means that the smallest building blocks form first and assemble to form a larger grain, which is oriented in a specific direction. To align all the building blocks, it is possible that they are first unstable and undergo transformation on assembly, during which their composition may change. By understanding and quantifying this process, the composition of the final fossil shell may be understood, ultimately leading to more reliable reconstructions of past environmental change.Key Points:
Hyaline foraminiferal shells are built of micrometer sized mesocrystalline units.
Biomineralization likely includes the formation and assembly of nanoparticles.
Nanometer sized units suggest nonâclassical crystal growth.https://doi.org/10.17617/3.D7HN3
Early attempts at desistance from crime: Prisonersâ prerelease expectations and their postrelease criminal behavior
Recent attention has been paid to the role of a positive outlook in early stages of the desistance process. The aim of this article is to examine prisonersâ own expectations regarding future offending before they are released, and why these expectations come true or not after their release from prison. Longitudinal data were used from in-depth interviews with 24 prisoners who were interviewed at the end of their sentence and three months after release about their future outlook on criminal activities, social capital and agency factors, and current criminal activities. Findings suggest a strong connection between criminal and non-criminal expectations and post-release criminal behavior.Criminal Justice: Legitimacy, accountability, and effectivit
Sex Offenders in Prison: Are They Socially Isolated?
Empirical literature has revealed that social isolation can affect the rehabilitation of sex offenders after serving their sentence. This process of social isolation can already start during incarceration due to strained relationships with fellow prisoners and correctional staff. The current study examined to what extent sex offenders felt socially isolated during incarceration, using survey and registered conviction data on a large sample of male adult prisoners from the Prison Project. It was found that support from and relationships with correctional officers and fellow prisoners were perceived less positive by sex offenders than nonsex offenders. No evidence was found for higher levels of loneliness in sex offenders compared with prisoners convicted for a nonsexual offense. In sum, although the effects were small, sex offenders reported more social isolation during imprisonment compared with nonsex offenders