150 research outputs found
Price changes around hedge fund trades: disentangling trading and disclosure effects
No full textPrevious studies find positive stock market reactions around announcements that hedge funds own large equity stakes in companies and use this evidence to support the hypothesis that hedge fund activism creates value. A concurrent explanation is that the price reaction reflects, at least in part, the market impact associated with hedge fund trades. We exploit the blockholder’s legal filing requirements with the Italian regulatory authority (CONSOB) to separately examine trading and disclosure effects associated with hedge fund trades. Trading effects are related to hedge funds’ buying activity on the market, whereas disclosure effects are related to the possibility that the market anticipates future activism and reacts to the announcement of hedge funds’ ownership. The trading effect is significantly larger than the disclosure effect. This result implies that the price impact associated with hedge fund purchases explains a large portion of the price reaction attributed exclusively to hedge fund activism in previous studies. We also find that trading by hedge funds produces a permanent change in the stock price, which occurs in equal part both prior to and concurrent to the trading activity. The execution strategy used by hedge funds to accumulate their position (on exchange or downstairs trading vs. block trading or upstairs) affects both the size and the temporal distribution of the trading effect
MDI: integrity index of cytoskeletal fibers observed by AFM
No full textThe Modified Directional Index (MDI) is a form factor of the angular spectrum computed from the 2D Fourier transform of an image marking the prevalence of rectilinear features throughout the picture. We study some properties of the index and we apply it to AFM images of cell cytoskeleton regions featuring patterns of rectilinear nearly parallel actin filaments as in the case of microfilaments grouped in bundles. The analysis of AFM images through MDI calculation quantifies the fiber directionality changes which could be related to fiber damages. This parameter is applied to the images of Hs 578Bst cell line, non-tumoral and not immortalized human epithelial cell line, irradiated with X-rays at doses equivalent to typical radiotherapy treatment fractions. In the reported samples, we could conclude that the damages are mainly born to the membrane and not to the cytoskeleton. It could be interesting to test the parameter also using other kinds of chemical or physical agents
Il silenzio degli agnelli: Risparmiatori e obbligazioni bancarie in Italia
No full textVerifichiamo l’efficacia della tutela dei risparmiatori che acquistano obbligazioni bancarie non strutturate attraverso l’osservazione (in periodi caratterizzati da diversa regolamentazione) di un elementare indicatore di convenienza: lo spread dichiarato dalla banca emittente rispetto a un titolo di Stato di pari durata. I risultati sono sorprendenti: pur esponendo i risparmiatori a un rischio superiore, le obbligazioni bancarie hanno offerto un rendimento inferiore di 22 basis points. Tale anomalia era inizialmente assai più grave (66 basis points); dopo il varo dell’obbligo di prospetto lo spread – sempre negativo – subisce una prima erosione, fino a 40 basis points; il differenziale è più basso per le obbligazioni emesse dopo il recepimento della direttiva MiFID (9 basis points) ma anche in tempi recenti continuano a sussistere zone d’ombra. Il cammino non è terminato, come dimostra la persistenza di spread negativi e l’ampliarsi del differenziale tra classi di banche, soprattutto con riferimento ad alcuni tipi di obbligazioni (segnatamente le step up). La morale non è nuova: migliori regole sono utili, il loro enforcement sarebbe ancor più utile
PS2.M: Looking for a potassium biosensor
No full textDNA sequences with guanine repeats are able to fold as G-quadruplex (G4) structures. This is an alternative DNA conformation in which four guanines are arranged as a tetrad, the structural unit of G4; two or more stacked tetrads form a G4 structure. The hydrogen bonds characterizing G4 are called Hoogsten bonds but more interactions are involved in the G4 structure stabilization. For example, cations work as G4 stabilizers and their role is not restricted to the structural folding. They coordinate the guanines’ carbonilic oxygens located towards the hydrophobic channel of the G4 inner structure. This feature suggests that the G4 could work as a cation biosensor. Biological media are characterized by the simultaneous presence of K+and Na+exhibiting different affinities and thus promoting different topological arrangements in the folding solution. In this article we explore the possibility of using PS2.M, an 18 base long synthetic oligonucleotide, as a detector of K+at concentrations in the range 0mM to 10mM. Our intent is therefore to study a biosensor that is made of the G4 sequence only, without intervention of other coupled molecules. As with most guanine-rich oligonucleotides, also PS2.M shows different structures depending on the folding conditions. In agreement with the literature data, our results outline the expected behavior and the key role of K+and Na+in promoting the folding, with Na+promoting the antiparallel structure formation of PS2.M, even at high concentrations. On the other hand, if PS2.M is folded in 10mM to 100mM KCl solutions, the parallel conformation sets in becoming more and more relevant as concentration grows. In a complex solution of G4 in the presence of both K+and Na+ions, spectra display the coexistence of parallel, antiparallel and mixed type conformations. Results show that the CD spectra values at this wavelength can be diagrammed as a function of the K+concentration to construct a biosensor calibration curve. In conclusion, given a Na+concentration in the range 50mM to 80mM and K+concentration in the range 0mM to 10mM, the measured CD signal at 263.6nm permits a K+concentration measurement with a resolution of ∼ 1 mM
Corporate Raiders, Performance and Governance in Europe
No full text"I analyse 136 block purchases made by corporate raiders in Europe between 1990 and 2001. Contrary to the hypothesis that these investors expropriate the target companies, there is a positive market reaction to the first public announcement of these purchases. In the long-run, raiders earn an abnormal profit when they sell their stakes. When they still held their positions at the end of the sample period, abnormal returns were insignificant. Raiders' activities do not improve operating performance. The findings are consistent with superior stock picking ability among these investors, but do not support the hypothesis that raiders are governance champions." Copyright 2007 The Author Journal compilation (c) 2007 Blackwell Publishing Ltd.
Multisensory Motion Perception in 3–4 Month-Old Infants
No full textHuman infants begin very early in life to take advantage of multisensory information by extracting the invariant amodal information that is conveyed redundantly by multiple senses. Here we addressed the question as to whether infants can bind multisensory moving stimuli, and whether this occurs even if the motion produced by the stimuli is only illusory. Three- to 4-month-old infants were presented with two bimodal pairings: visuo-tactile and audio-visual. Visuo-tactile pairings consisted of apparently vertically moving bars (the Barber Pole illusion) moving in either the same or opposite direction with a concurrent tactile stimulus consisting of strokes given on the infant’s back. Audio-visual pairings consisted of the Barber Pole illusion in its visual and auditory version, the latter giving the impression of a continuous rising or ascending pitch. We found that infants were able to discriminate congruently (same direction) vs. incongruently moving (opposite direction) pairs irrespective of modality (Experiment 1). Importantly, we also found that congruently moving visuo-tactile and audio-visual stimuli were preferred over incongruently moving bimodal stimuli (Experiment 2). Our findings suggest that very young infants are able to extract motion as amodal component and use it to match stimuli that only apparently move in the same direction
Urban Road Pricing: A Comparative Study on the Experiences of London, Stockholm and Milan
No full textAbstractUrban road pricing schemes have been designed in order to reduce externalities generated by traffic. Main impacts regard: time loss due to congestion, local pollution, noise, contribution to climate change caused by emissions of GHGs, pavement costs and road damages, increase in accidents risks, extra-fuel consumption, decrease in quality of life. Moreover road pricing schemes generate public revenues.The paper performs a comparative evaluation of the three main experiences of urban road pricing in Europe: London (in operations since 2003), Stockholm (in operations since 2007, after a period of trial in 2006) and Milan (in operations since 2008, with a shift from pollution to congestion charge in 2012). Since their launch, the schemes have been adjusted in terms of amount of charge, area of application and other features.The schemes have been able to reduce negative externalities generated by traffic, such as accidents, congestion and emissions, up to different levels. A comparative analysis of the three schemes is provided. Determinants of differences in the effectiveness of the schemes are evaluated with a particular focus on elasticity of use of private vehicles to charge.The results can be useful to design well targeted congestion charge schemes and to assess their efficacy
I sistemi dei permessi trasferibili: caratteristiche, regole di funzionamento e scale territoriali
No full textIl rapporto esamina i recenti sistemi di permessi trasferibili di emissioni di gas climalteranti a diverse scale territoriali. Viene definito un modello di simulazione di emission trading a scala regionale e valutati i suoi effetti economici ed ambientali
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