The election of Donald J. Trump challenged some long-held core tenets of US foreign policy. For decades, US administrations have valued the nonproliferation of nuclear weapons among their most ...important foreign policy goals. At the same time, Washington has expanded its global influence by extending robust security guarantees to numerous countries around the globe. Finally, the US has established strategic stability vis-à-vis its nuclear adversaries by relying heavily on the doctrine of deterrence. These three policies, as the analysis below will show, are deeply connected. Security assurances to allies, combined with a focus on deterring -- rather than rolling back -- adversary regimes, have long been among the most effective tools in Washington’s nuclear nonproliferation toolkit. The limited spread of nuclear weapons that resulted from these policies, in turn, has made it possible for the US to expand its global influence and achieve its broader strategic goals at relatively low cost, avoiding major wars against nuclear adversaries and exercising a great deal of influence over its protégés.
The Yeast search for transcriptional regulators and consensus tracking (YEASTRACT) information system (www.yeastract.com) was developed to support the analysis of transcription regulatory ...associations in Saccharomyces cerevisiae. Last updated in September 2007, this database contains over 30 990 regulatory associations between Transcription Factors (TFs) and target genes and includes 284 specific DNA binding sites for 108 characterized TFs. Computational tools are also provided to facilitate the exploitation of the gathered data when solving a number of biological questions, in particular the ones that involve the analysis of global gene expression results. In this new release, YEASTRACT includes DISCOVERER, a set of computational tools that can be used to identify complex motifs over-represented in the promoter regions of co-regulated genes. The motifs identified are then clustered in families, represented by a position weight matrix and are automatically compared with the known transcription factor binding sites described in YEASTRACT. Additionally, in this new release, it is possible to generate graphic depictions of transcriptional regulatory networks for documented or potential regulatory associations between TFs and target genes. The visual display of these networks of interactions is instrumental in functional studies. Tutorials are available on the system to exemplify the use of all the available tools.
We present the YEAst Search for Transcriptional Regulators And Consensus Tracking (YEASTRACT; www.yeastract.com) database, a tool for the analysis of transcription regulatory associations in ...Saccharomyces cerevisiae. This database is a repository of 12 346 regulatory associations between transcription factors and target genes, based on experimental evidence which was spread throughout 861 bibliographic references. It also includes 257 specific DNA-binding sites for more than a hundred characterized transcription factors. Further information about each yeast gene included in the database was obtained from Saccharomyces Genome Database (SGD), Regulatory Sequences Analysis Tools and Gene Ontology (GO) Consortium. Computational tools are also provided to facilitate the exploitation of the gathered data when solving a number of biological questions as exemplified in the Tutorial also available on the system. YEASTRACT allows the identification of documented or potential transcription regulators of a given gene and of documented or potential regulons for each transcription factor. It also renders possible the comparison between DNA motifs, such as those found to be over-represented in the promoter regions of co-regulated genes, and the transcription factor-binding sites described in the literature. The system also provides an useful mechanism for grouping a list of genes (for instance a set of genes with similar expression profiles as revealed by microarray analysis) based on their regulatory associations with known transcription factors.
Key message
We present a detailed protocol for isolation of single sperm cells and transcriptome analysis to study variation in gene expression between sperm cells.
Male gametophyte development in ...flowering plants begins with a microspore mother cell, which upon two consecutive cell divisions forms a mature pollen grain containing a vegetative nucleus and two sperm cells. Pollen development is a highly dynamic process, involving changes at both the transcriptome and epigenome levels of vegetative nuclei and the pair of sperm cells that have their own cytoplasm and nucleus. While the overall transcriptome of Arabidopsis pollen development is well documented, studies at single-cell level, in particular of sperm cells, are still lacking. Such studies would be essential to understand whether and how the two sperm cells are transcriptionally different, in particular once the pollen tube grows through the transmitting tissue of the pistil. Here we describe a detailed protocol for isolation of single sperm cells from growing pollen tubes and analysis of their transcriptome.
Purpose:
To provide a spectral-domain optical coherence tomography (SD-OCT)-based analysis of retinal layers thickness and nasal displacement of closed macular hole after internal limiting membrane ...peeling in macular hole surgery.
Methods:
In this nonrandomized prospective interventional study, 36 eyes of 32 patients were subjected to pars plana vitrectomy and 3.5 mm diameter internal limiting membrane (ILM) peeling for idiopathic macular hole (IMH). Nasal and temporal internal retinal layer thickness were assessed with SD-OCT. Each scan included optic disc border so that distance between optic disc border and fovea were measured.
Results:
Thirty-six eyes had a successful surgery with macular hole closure. Total nasal retinal thickening (p<0.001) and total temporal retinal thinning (p<0.0001) were observed. Outer retinal layers increased thickness after surgery (nasal p<0.05 and temporal p<0.01). Middle part of inner retinal layers (mIRL) had nasal thickening (p<0.001) and temporal thinning (p<0.05). The mIRL was obtained by deducting ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL) thickness from overall thickness of the inner retinal layer. Papillofoveal distance was shorter after ILM peeling in macular hole surgery (3,651 ± 323 μm preoperatively and 3,361 ± 279 μm at 6 months; p<0.0001).
Conclusions:
Internal limiting membrane peel is associated with important alteration in inner retinal layer architecture, with thickening of mIRL and shortening of papillofoveal distance. These factors may contribute to recovery of disrupted foveal photoreceptor and vision improvement after IMH closure.
General Nuclear Compellence Anderson, Nicholas D.; Debs, Alexandre; Monteiro, Nuno P.
Strategic studies quarterly : SSQ,
10/2019, Letnik:
13, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The study of compellence has focused on crisis situations. However, compellence may work without crises. If a state possesses the capability to compel a target, the target may choose to make ...concessions to avoid a crisis and dampen the risk of conflict. This constitutes a form of “general compellence.” As with general deterrence, failures in general compellence will result in crises. We discuss this notion of general compellence in the context of nuclear proliferation. Nuclearization may give a state greater ability to compel others by threatening nuclear escalation. This ability yields general compellence leverage vis-à-vis its allies and adversaries. Facing the risk of nuclear escalation, the state’s adversaries may offer political concessions, leading to improved relations and détente. The state’s allies may offer additional security commitments to diminish the risk that the new nuclear state will use its weapons, leading to tighter alliance relationships. We illustrate our arguments with case studies of France, China, Israel, and South Africa in the aftermath of their nuclear acquisition.
Robert Jervis's System Effects was published just as systems thinking began to decline among political scientists, who were adopting increasingly strict standards of causal identification, ...privileging experimental and large-N studies. Many politically consequential system effects are not amenable to research designs that meet these standards, yet they must nonetheless be studied if the most important questions of international politics are to be answered. For example, if nuclear weapons are considered in light of their effect on the international system as a whole, it becomes clear that they have obviated the need for a global balance of power by allowing states to counterbalance threats by acquiring nuclear weapons rather than investing in massive conventional balancing efforts. Similarly, systems thinking should inform our understanding of the impact of a "unipolar power" such as the United States, which has enjoyed an overwhelming preponderance of conventional military power since the fall of the Berlin Wall. A unipolar power is likely to become involved in frequent conflicts because it is not restrained by the presence of a peer competitor.
PDF
