410 research outputs found
A transcranial magnetic stimulation study on the role of the left intraparietal sulcus in temporal orienting of attention
likely to occur. Temporal orienting of attention has been consistently associated with activation of the left
intraparietal sulcus (IPS) in prior fMRI studies. However, a direct test of its causal involvement in temporal
orienting is still lacking. The present study tackled this issue by transiently perturbing left IPS activity with either
online (Experiment 1) or offline (Experiment 2) transcranial magnetic stimulation (TMS). In both experiments,
participants performed a temporal orienting task, alternating between blocks in which a temporal cue predicted
when a subsequent target would appear and blocks in which a neutral cue provided no information about target
timing. In Experiment 1 we used an online TMS protocol, aiming to interfere specifically with cue-related
temporal processes, whereas in Experiment 2 we employed an offline protocol whereby participants performed
the temporal orienting task before and after receiving TMS. The right IPS and/or the vertex were
stimulated as active control regions. While results replicated the canonical pattern of temporal orienting effects
on reaction time, with faster responses for temporal than neutral trials, these effects were not modulated by TMS
over the left IPS (as compared to the right IPS and/or vertex regions) regardless of the online or offline protocol
used. Overall, these findings challenge the causal role of the left IPS in temporal orienting of attention inviting
further research on its underlying neural substratesFrench National Research Agency (ANR) ANR-18-CE28-0009-01MCIN/AEI/10.13039/501100011033 PID2021- 128696NA-I00"ERDF A way of making Europe"Spanish GovernmentEuropean Union Next GenerationMinistry of Economy, Knowledge, EnterpriseUniversities of AndalusiaMinistry of Science and Innovation, Spain (MICINN)
Spanish Government PSI2017-88136EDER-Junta de AndaluciaUniversidad de Granada/CBU
Polaronic optical absorption in electron-doped and hole-doped cuprates
Polaronic features similar to those previously observed in the photoinduced
spectra of cuprates have been detected in the reflectivity spectra of
chemically doped parent compounds of high-critical-temperature superconductors,
both -type and -type. In NdCuO these features, whose
intensities depend both on doping and temperature, include local vibrational
modes in the far infrared and a broad band centered at 1000 cm.
The latter band is produced by the overtones of two (or three) local modes and
is well described in terms of a small-polaron model, with a binding energy of
about 500 cm. Most of the above infrared features are shown to survive
in the metallic phase of NdCeCu0, BiSrCuO, and
YBaCuO, where they appear as extra-Drude peaks. The occurrence
of polarons is attributed to local modes strongly coupled to carriers, as shown
by a comparison with tunneling results.Comment: File latex, 31 p., submitted to Physical Review B. Figures may be
faxed upon reques
Infrared signatures of charge stripes in La(2-x)Sr(x)CuO(4)
The in-plane optical conductivity of seven La(2-x)Sr(x)CuO(4) single crystals
with x between 0 and 0.15 has been studied from 30 to 295 K. All doped samples
exhibit strong peaks in the far-infrared, which closely resemble those observed
in Cu-O "ladders" with one-dimensional charge-ordering. The behavior with
doping and temperature of the peak energy, width, and intensity allows us to
conclude that we are observing charge stripes dynamics in La(2-x)Sr(x)CuO(4) on
the fast time scale of infrared spectroscopy.Comment: 9 pages including figs. in pdf forma
Chronic diarrhea associated with persistent norovirus excretion in patients with chronic lymphocytic leukemia: report of two cases
BACKGROUND: Chronic diarrhea in patients treated with immunosuppressive agents or suffering from immunosuppressive disease can represent a diagnostic and therapeutic challenge to the clinician. Norovirus infection, a major cause of acute epidemic diarrhea, has been described as a cause of chronic diarrhea in patients who are immunosuppressed, including transplant recipients and the very young. CASE PRESENTATIONS: We describe two patients, a 64 year-old man and a 59 year-old woman, both suffering from chronic lymphocytic leukemia and hypogammaglobulinemia, who developed chronic diarrhea resistant to therapy. In both cases, after months of symptoms, persistent norovirus infection--documented by repeatedly-positive high-sensitivity stool enzyme immunoassay--was found to be the cause. Both patients died with active diarrheal symptoms. CONCLUSIONS: We describe the first cases of advanced chronic lymphocytic leukemia to suffer from chronic symptomatic norovirus infection. Clinicians caring for such patients, particularly those with concomitant hypogammaglobulinema, who have chronic unexplained diarrhea, should consider norovirus infection in the differential diagnosis
p53 protein regulates the effects of amifostine on apoptosis, cell cycle progression, and cytoprotection
The effects of private equity investors on the governance of firms
Companies that receive external equity typically experience a separation of ownership and control, where owners who are not involved in the company (principals) have to rely on the management team (agents) for achieving expected goals and target levels. Theoretical literature argues that when ownership and control are separated, principals develop governance structures to reduce agency costs and align agents’ incentives (Berle and Means, 1932; Jensen and Meckling, 1976; Grossman and Hart, 1986; Zingales, 1995). Likewise, optimal financial structure design by financial intermediaries can effectively help to mitigate agency problems by identifying self-enforcing equilibria (Diamond, 1984; Fama and Jensen, 1985; Stiglitz, 1985; Bhattacharya and Thakor, 1993; Barry, 1994).
In general terms, governance and financial devices can be thought of as either internal control mechanisms (such as the board) or external control mechanisms (such as the market for corporate control). An increasingly important external control mechanism affecting the governance of young and fast-growing companies worldwide is the emergence of institutional and private equity investors, as equity owners. Institutional investors have the potential to influence management’s activities directly through their ownership, and indirectly by trading their shares (Gillan and Starks, 2003). In this respect private equity investors are differentiated from institutional ones in the longer-term view and in the significantly more hands-on approach that they pursue when investing in a portfolio company. As a result, companies backed by private equity investors represent a fruitful environment to investigate the use and efficiency of a multitude of control mechanisms.
The surge over the last 30 years in investment activity by private equity investors at large has given rise to an increased specialization of this class of investors conditional on the risk return profiles associated with different investment and firm life cycle stages. For instance, business angels supporting the archetypical ‘paper company’ start-up face a risk exposure that in terms of both magnitude and characteristics is significantly different from that incurred by a private equity investor acquiring control of a mature company. Yet, investors in this market share common traits such as a value maximization approach, risk‒return informed decisions, and a deep knowledge of governance mechanisms. As such their influence on portfolio company governance mechanisms is largely similar in terms of depth and breadth. In this chapter we aim at presenting an up-to-date review of the main theoretical contributions and empirical results in this active and growing field of research
Colossal dielectric constants in transition-metal oxides
Many transition-metal oxides show very large ("colossal") magnitudes of the
dielectric constant and thus have immense potential for applications in modern
microelectronics and for the development of new capacitance-based
energy-storage devices. In the present work, we thoroughly discuss the
mechanisms that can lead to colossal values of the dielectric constant,
especially emphasising effects generated by external and internal interfaces,
including electronic phase separation. In addition, we provide a detailed
overview and discussion of the dielectric properties of CaCu3Ti4O12 and related
systems, which is today's most investigated material with colossal dielectric
constant. Also a variety of further transition-metal oxides with large
dielectric constants are treated in detail, among them the system La2-xSrxNiO4
where electronic phase separation may play a role in the generation of a
colossal dielectric constant.Comment: 31 pages, 18 figures, submitted to Eur. Phys. J. for publication in
the Special Topics volume "Cooperative Phenomena in Solids: Metal-Insulator
Transitions and Ordering of Microscopic Degrees of Freedom
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Recent Developments Affecting Golf Course Design (page 1) From the Editor (3) Five Year Results (3) Turf Management Club News (4) Quotes from 1960 Seniors (5) Poa annua - - Friend or Foe (6) The Horticulture Show (7) Cartoons (8) Message from the Winter School President of 1960 (10) The Most Outstanding Turf Senior for 1959 (10) The Value of the Proper Use of Lime (11) Summer Placement (12) A Greenhouse on the Golf Course (13) More Opportunities in the Future for the Aggressive Superintendent at Country Clubs (14) Soil, Sawdust and Turfgrass (15) Picture - Senior Stockbridge Turf majors (16) Picture - Freshman Stockbridge Turf majors (17) Susceptibility of Merion Bluegrass to Stripe Smut (18) Bents in the South (19) Picture - Honorary Members of Turf Management Club (20) Picture - Graduates of Winter School for Turf mangers- 1960 (21) Weather - We are Going to Have Weather, Whether or Not - What Should we Expect by O. Tennebaum & R. E. Lautzenheiser (A-1) The Nature of Winter Injury to Plants by Dr. Johnson Parker (A-1) Turf Problems: You Name it and We\u27ve Had It in \u2759 by Alexander Radko ad T.T. Taylor (A-3) Topdressing Experiences with Greens at Century by James Fulwider (A-5) Poa annua - Fairway Rennovation at winged Foot by Sherwood A. Moore (A-6) Winter Problems at Ekwanaok by Paul O\u27Leary (A-8) Progress Through Drainage by Kayem Ovian (A-10) Winter Injury on Home Lawns by Orlando Capizzi (A-12) The Status of Pre-emergence Chemicals for the Control of Crabgrass by Dr. E. Engel (A-12) Turf Nurseries - Establishment, Maintenance & Utilization by Robert Grant (A-14) Soil Compaction by Dr. R. B. Alderfer (A-16) Water Management Practices on Turf Areas by Dr. J.R. Watson (A-18) Getting to Know Your Members by Owen Griffith (A-23) New Trends in Clubhouse Landscaping by Alfred Boicourt (A-26) General Lawn Management (Alternate Session) Conserving Soil for a good Lawn by Dr. William G. Colby (A-27) Fertilizting and Liming by Dr. Joseph Steckel (A-28) Grasses and Grass Mixtures for New England Lawns by Dr. Robert Schery (A-29) The Care and Maintenance of Establishment Lawns by Dr. John R. Davi
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