Shielding experimental methods

Benchmark, parametric, and design-confirmation shielding measurements are made at the Tower Shielding Facility (TSF) in Oak Ridge. A powerful reactor (to 1 MW thermal) is used with spectral modifiers to provide neutron spectra close to those associated with the various parts of an LMFBR. The source strength allows measurements through shields of full reactor thickness using sensitive detectors. The detectors include spectrometers and dosimeters for both neutrons and gamma rays. A large exclusion area provides much flexibility in arranging shield assemblies to be studied

How not to attack intelligent design creationism: philosophical misconceptions about methodological naturalism

In recent controversies about Intelligent Design Creationism (IDC), the principle of methodological naturalism (MN) has played an important role. In this paper, an often neglected distinction is made between two different conceptions of MN, each with its respective rationale and with a different view on the proper role of MN in science. According to one popular conception, MN is a self-imposed or intrinsic limitation of science, which means that science is simply not equipped to deal with claims of the supernatural (Intrinsic MN or IMN). Alternatively, we will defend MN as a provisory and empirically grounded attitude of scientists, which is justified in virtue of the consistent success of naturalistic explanations and the lack of success of supernatural explanations in the history of science (Provisory MN or PMN). Science does have a bearing on supernatural hypotheses, and its verdict is uniformly negative. We will discuss five arguments that have been proposed in support of IMN: the argument from the definition of science, the argument from lawful regularity, the science stopper argument, the argument from procedural necessity, and the testability argument. We conclude that IMN, because of its philosophical flaws, proves to be an ill-advised strategy to counter the claims of IDC. Evolutionary scientists are on firmer ground if they discard supernatural explanations on purely evidential grounds, instead of ruling them out by philosophical fiat

Synapsin II Is Involved in the Molecular Pathway of Lithium Treatment in Bipolar Disorder

Bipolar disorder (BD) is a debilitating psychiatric condition with a prevalence of 1–2% in the general population that is characterized by severe episodic shifts in mood ranging from depressive to manic episodes. One of the most common treatments is lithium (Li), with successful response in 30–60% of patients. Synapsin II (SYN2) is a neuronal phosphoprotein that we have previously identified as a possible candidate gene for the etiology of BD and/or response to Li treatment in a genome-wide linkage study focusing on BD patients characterized for excellent response to Li prophylaxis. In the present study we investigated the role of this gene in BD, particularly as it pertains to Li treatment. We investigated the effect of lithium treatment on the expression of SYN2 in lymphoblastoid cell lines from patients characterized as excellent Li-responders, non-responders, as well as non-psychiatric controls. Finally, we sought to determine if Li has a cell-type-specific effect on gene expression in neuronal-derived cell lines. In both in vitro models, we found SYN2 to be modulated by the presence of Li. By focusing on Li-responsive BD we have identified a potential mechanism for Li response in some patients

Regulation of cell-to-cell communication mediated by astrocytic ATP in the CNS

It has become apparent that glial cells, especially astrocytes, not merely supportive but are integrative, being able to receive inputs, assimilate information and send instructive chemical signals to other neighboring cells including neurons. At first, the excitatory neurotransmitter glutamate was found to be a major extracellular messenger that mediates these communications because it can be released from astrocytes in a Ca2+-dependent manner, diffused, and can stimulate extra-synaptic glutamate receptors in adjacent neurons, leading to a dynamic modification of synaptic transmission. However, recently extracellular ATP has come into the limelight as an important extracellular messenger for these communications. Astrocytes express various neurotransmitter receptors including P2 receptors, release ATP in response to various stimuli and respond to extracellular ATP to cause various physiological responses. The intercellular communication “Ca2+ wave” in astrocytes was found to be mainly mediated by the release of ATP and the activation of P2 receptors, suggesting that ATP is a dominant “gliotransmitter” between astrocytes. Because neurons also express various P2 receptors and synapses are surrounded by astrocytes, astrocytic ATP could affect neuronal activities and even dynamically regulate synaptic transmission in adjacent neurons as if forming a “tripartite synapse” In this review, we summarize the role of astrocytic ATP, as compared with glutamate, in gliotransmission and synaptic transmission in neighboring cells, mainly focusing on the hippocampus. Dynamic communication between astrocytes and neurons mediated by ATP would be a key event in the processing or integration of information in the CNS

The many faces of biological individuality

Biological individuality is a major topic of discussion in biology and philosophy of biology. Recently, several objections have been raised against traditional accounts of biological individuality, including the objections of monism (the tendency to focus on a single individuality criterion and/or a single biological field), theory-centrism (the tendency to discuss only theory-based individuation), ahistoricity (the tendency to neglect what biologists of the past and historians of biology have said about biological individuality), disciplinary isolationism (the tendency to isolate biological individuality from other scientific and philosophical domains that have investigated individuality), and the multiplication of conceptual uncertainties (the lack of a precise definition of “biological individual” and related terms). In this introduction, I will examine the current philosophical landscape about biological individuality, and show how the contributions gathered in this special issue address these five objections. Overall, the aim of this issue is to offer a more diverse, unifying, and scientifically informed conception of what a biological individual is