No longer true

There are sentences that express the same temporally fully specified proposition at all contexts--call them 'context-insensitive, temporally specific sentences.' Sentence (1) 'Obama was born in 1961' is a case in point: at all contexts, it expresses the proposition ascribing to the year 1961 the property of being a time in which Obama was born. Suppose that someone uttered (1) in a context located on Christmas 2000 in our world. In this context, (1) is a true sentence about the past. Moreover, it seems impossible that (1) will be false in a successive context (one located, say, on Christmas 2020 in our world). More generally, one might be tempted to endorse the following principle: if a context-insensitive, temporally specific sentence is uttered in a context in which it is about the past and takes a certain truth value in this context, it cannot be the case that it takes a different truth value in a successive context located in the same world. In this paper, we present linguistic evidence that shows that this principle fails. On this basis, we draw an apparently crazy conclusion: the past can change. We then explain why this conclusion is not that crazy, after all

The puzzle of the changing past

If you utter sentence (1) ‘Obama was born in 1961’ now, you say something true about the past. Since the past will always be such that the year 1961 has the property of being a time in which Obama was born, it seems impossible that (1) could ever be false in a future context of utterance. We shall consider the case of a sentence about the past exactly like (1), but which was true when uttered a few years ago and is no longer true now. On this basis, we shall conclude that the past has changed

The role of Micro-RNAs in Hepatocellular Carcinoma: From Molecular Biology to Treatment

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third leading cause of cancer deaths. microRNAs (miRNAs) are evolutionary conserved small non-coding RNA that negatively regulate gene expression and protein translation. Recent evidences have shown that they are involved in many biological processes, from development and cell-cycle regulation to apoptosis. miRNAs can behave as tumor suppressor or promoter of oncogenesis depending on the cellular function of their targets. Moreover, they are frequently dysregulated in HCC. In this review we summarize the latest findings of miRNAs regulation in HCC and their role as potentially diagnostic and prognostic biomarkers for HCC. We highlight development of miRNAs as potential therapeutic targets for HCC

Protonography, a new technique for the analysis of carbonic anhydrase activity.

All proteolytic enzymes, which are able to renature and reacquire the proteolytic activity on a copolymerized substrate, can be analyzed by zymography upon removal of sodium dodecyl sulfate (SDS). Protonography, the new technique described in this study, unlike zymography, allows the detection of a different protein, not a protease, i.e. of the carbonic anhydrase (CA, EC 4.2.1.1) activity on a SDS polyacrylamide gel electrophoresis gel. CAs are zinc-containing enzymes that catalyze the reversible conversion of carbon dioxide to bicarbonate and protons. Hydrogen ions produced during the catalyzed reaction are responsible for the change of color that appears on the gel around the CA band. For this reason, we named the new technique "protonography". The following four salient features characterize this new technique: (a) on the basis of molecular weight markers, recombinant or native CAs with different molecular weights can be detected and quantified rapidly on a single gel; (b) the hydratase activity can be reversibly inhibited by SDS during electrophoresis and recovered by incubating the gel in aqueous Triton X-100; (c) it is possible to separate active oligomeric forms of CAs on the gel enabling their activities to be determined independently of one another. This feature is not possible when using solution assays; and (d) it can be a useful tool to establish if a putative or a newly identified CA in a genome is expressed and enzymatically active. This article outlines the general principles employed in protonography, providing an easy procedure to implement it in laboratories working with CAs. It also presents an overview of its development and current research applications through specific examples

INVESTIGATION ACTIVITY ABOUT A COLLAPSED STEEL STRUCTURE SUBJECTED TO A REAL FIRE, Fire scenarios and structural behaviour of a real steel structure

The paper describes the behaviour ofa real steel structure collapsed under a fire event. 3D structural analyses were performed with SAFIR program (J-M Franssen, 2005). Different modellingare implemented with some fire load models and analyses of thebehaviour of the whole structure. The main purpose of this work was to investigate the failure types of a warehouse structure under fire conditions. Different fire conditions were applied to the steel frame sections, with ISOcurve (ISO EN 834-8:2002) and zone model approach. The analyses show that with unprotected steel sections, horizontal structures are more critical than columns. Trough applying a performance basedapproach,structure has 30 minutes of fire resistance

‘Must’ implies ‘can’

An open question in the semantics of modality is what relations there are among different modal flavours. In this article, we consider the thorny issue of whether ascribing to an agent the obligation to φ implies that it is possible for the agent to φ. Traditionally, this issue has been interpreted as whether ‘ought’ implies ‘can’. But another linguistic interpretation is available as well, namely, whether ‘must’ implies ‘can’ (MIC). We show that ‘must’ does imply ‘can’ via a convergent argument. The first strand of the argument is theoretical: it consists in proving MIC from a well-established theory of modality in natural language, i.e., that proposed by Kratzer. The second strand is empirical: we present novel acceptability judgment studies showing that MIC predicts and explains the linguistic behaviour of native English speakers