5,018 research outputs found
Worker policing by egg eating in the ponerine ant Pachycondyla inversa
We investigated worker policing by egg eating in the ponerine ant Pachycondyla inversa, a species with
morphologically distinct queens and workers. Colonies were split into one half with the queen and one
half without. Workers in queenless colony fragments started laying unfertilized male eggs after three weeks.
Worker-laid eggs and queen-laid eggs were introduced into five other queenright colonies with a single
queen and three colonies with multiple queens, and their fate was observed for 30 min. Significantly more
worker-laid eggs (range of 35–62%, mean of 46%) than queen-laid eggs (range of 5–31%, mean of 15%)
were eaten by workers in single-queen colonies, and the same trend was seen in multiple-queen colonies.
This seems to be the first well-documented study of ants with a distinct caste polymorphism to show that
workers kill worker-laid eggs in preference to queen-laid eggs. Chemical analyses showed that the surfaces
of queen-laid and worker-laid eggs have different chemical profiles as a result of different relative proportions
of several hydrocarbons. Such differences might provide the information necessary for differential
treatment of eggs. One particular alkane, 3,11-dimeC27, was significantly more abundant on the surfaces
of queen-laid eggs. This substance is also the most abundant compound on the cuticles of egg layers
HST Proper Motion confirms the optical identification of the nearby pulsar PSR 1929+10
We report on the proper motion measurement of the proposed optical
counterpart of the X-ray/radio pulsar PSR 1929+10. Using images obtained with
the HST/STIS (average epoch 2001.73) we computed a yearly displacement of +97
+/- 1 mas yr^{-1} in RA and +46 +/- 1 mas yr^{-1} in Dec since the epoch
(1994.52) of the original HST/FOC detection. Both the magnitude and direction
of the optical proper motion components are found to be fully consistent with
the most recent VLBA radio measurements. This result provides an unambiguous
confirmation of the pulsar optical identification. In addition, we have used
the combined STIS/FOC datasets to derive information on the pulsar spectrum,
which seems characterized by a power law component, apparently unrelated to the
X-ray emission.Comment: 12 pages, 3 figures, submitted to ApJ Letter
Printable Nanoscopic Metamaterial Absorbers and Images with Diffraction-Limited Resolution
The fabrication of functional metamaterials with extreme feature resolution
finds a host of applications such as the broad area of surface/light
interaction. Non-planar features of such structures can significantly enhance
their performance and tunability, but their facile generation remains a
challenge. Here, we show that carefully designed out-of-plane nanopillars made
of metal-dielectric composites integrated in a metal-dielectric-nanocomposite
configuration, can absorb broadband light very effectively. We further
demonstrate that electrohydrodynamic printing in a rapid nanodripping mode, is
able to generate precise out-of-plane forests of such composite nanopillars
with deposition resolutions at the diffraction limit on flat and non-flat
substrates. The nanocomposite nature of the printed material allows the
fine-tuning of the overall visible light absorption from complete absorption to
complete reflection by simply tuning the pillar height. Almost perfect
absorption (~95%) over the entire visible spectrum is achieved by a nanopillar
forest covering only 6% of the printed area. Adjusting the height of individual
pillar groups by design, we demonstrate on-demand control of the gray scale of
a micrograph with a spatial resolution of 400 nm. These results constitute a
significant step forward in ultra-high resolution facile fabrication of
out-of-plane nanostructures, important to a broad palette of light design
applications. nanostructures, important to a broad palette of light design
applications
Innovazioni made in Italy nel management alberghiero. La realt\ue0 degli "alberghi diffusi"
Le evoluzioni in atto nel mondo del turismo sembrano aprire nuovi orizzonti alla qualificazione dei servizi recettivi, sia alberghieri sia extraalberghieri. Particolarmente, la tendenza, almeno tra le popolazioni economicamente pi\uf9 evolute, a dare maggiore enfasi alla qualit\ue0 della vita e, conseguentemente, alla dimensioni pi\uf9 qualitativa del tempo libero che si intende dedicare ad attivit\ue0 turistiche, sembra sollecitare ripensamenti nei modelli in uso in questo particolare ambito. Si assiste, da un lato, ad una richiesta di servizi ricettivi personalizzati e di pi\uf9 elevata qualit\ue0, dall'altro lato ad un turista sempre pi\uf9 sensibile agli aspetti culturali ed esperenziali della propria vita, aperto alla riscoperta del territorio e delle sue autenticit\ue0.
Se l'albergo deve offrire esperienze nuove e differenziate di ospitalit\ue0, allora deve partire non gi\ue0 dalla gestione dello "spazio", bens\uec dalla gestione del tempo "co-vissuto" dall'ospite nel processo di produzione-erogazione del servizio offerto. Lo \u201cspazio\u201d (edificio) resta importante ma in via strumentale.
Obiettivo di questo lavoro \ue8 evidenziare la centralit\ue0 del fattore tempo e l'opportunit\ue0 di considerarlo legato alla conoscenza e alla leadership nell'impresa alberghiera, specie allorch\ue9 si ponga il problema dell\u2019innovazione.
Siffatto legame, finora poco approfondito negli studi sull\u2019argomento, pu\uf2 rivelarsi prezioso sotto un duplice profilo. Esso infatti, se ben gestito, pu\uf2 favorire non solo la qualit\ue0 delle relazioni all\u2019interno dell\u2019albergo, preservandone l\u2019unit\ue0 e l\u2019integrit\ue0 sistemica, ma anche e soprattutto un orientamento culturale alla coevoluzione impresa-ambiente.
La leadership, intesa come forza integratrice di valori ed esigenze anche cognitive e temporali, esistenti dentro e fuori l\u2019impresa, pu\uf2 svolgere un ruolo rilevante nel favorire coerenze dinamiche tra l\u2019impresa e l\u2019ambiente, anche nell\u2019ottica della sostenibilit\ue0.
Oggetto privilegiato dell\u2019analisi sono le imprese alberghiere di piccole e medie dimensioni, realt\ue0 prevalente nel comparto ricettivo in Italia, a fronte di una pressione competitiva che si rivela sempre pi\uf9 forte dal punto di vista sia quantitativo sia qualitativo e di fatto globale.
Si presenta quindi il caso dell\u2019 \u201calbergo diffuso\u201d Sextantio, apprezzato nel mondo per l\u2019innovativit\ue0 della sua formula imprenditoriale, analizzandone le ricadute in termini di competitivit\ue0 dell\u2019impresa e della destinazione turistica
CoQ10 and vitamin A supplementation support voice rehabilitation. A double-blind, randomized, controlled, three-period cross-over pilot study
Objectives: To evaluate the effectiveness of an adjuvant therapy (CoQ10 in its watersoluble form and vitamin A) in supporting voice rehabilitation in a large group of patients with muscle tension dysphonia (MTD). Study Design: Twelve-week, double-blind, randomized, controlled, three-period crossover pilot study. The primary endpoint was the change in the Dysphonia Severity Index (DSI) over the 12-week study period. Secondary endpoints were the changes in the subcomponents of DSI, including MPT, F0-high, I-low, and jitter. Exploratory endpoints were the changes in the Shimmer and in Voice Handicap Index (VHI). Methods: Patients were randomly assigned in a 1:1 ratio to two counter-balanced arms. Group A (ADJ-PLA) patients were administered QTer 300 mg and Vit A acetate 500.000 Ul/g 1 mg twice daily for a 4-week intervention period, followed by a 4-week period of wash-out, and then were submitted to a last 4-week period of placebo. Patients in Group B (PLB-ADJ) were given the treatment period in reverse order. Both groups received a 45-min voice therapy in a group format once a day for 4 weeks during the first and the second active periods. The therapy was held during the wash-out period. Results: The analysis of main time effect indicated a trend toward recovery of vocal function regardless of group assignment. A significant time by group effect was found on DSI [F = 3.4 (2.5, 80.5), p = 0.03], F0-high [F = 4.5 (2.6, 82.9), p = 0.008] and Shimmer [F = 3.6 (1.5, 46.9), p = 0.048], under CoQ10 and Vit A treatment, with a small effect size. There was no significant time by group effect on the other study measures, namely MPT, I-low, VHI. Conclusions: A trend toward recovery of vocal function was observed in all the patients, likely due to voice rehabilitation. The improvement of DSI was greater under CoQ10 and Vitamin treatment, indicating a more pronounced improvement of vocal quality under adjuvant therapy. The study protocol was reviewed and approved by the Ethics Committee of Policlinico Umberto I Hospital, Rome, Italy Rif. 3069/13.02.2014
TMS-evoked long-lasting artefacts: A new adaptive algorithm for EEG signal correction
OBJECTIVE:
During EEG the discharge of TMS generates a long-lasting decay artefact (DA) that makes the analysis of TMS-evoked potentials (TEPs) difficult. Our aim was twofold: (1) to describe how the DA affects the recorded EEG and (2) to develop a new adaptive detrend algorithm (ADA) able to correct the DA.
METHODS:
We performed two experiments testing 50 healthy volunteers. In experiment 1, we tested the efficacy of ADA by comparing it with two commonly-used independent component analysis (ICA) algorithms. In experiment 2, we further investigated the efficiency of ADA and the impact of the DA evoked from TMS over frontal, motor and parietal areas.
RESULTS:
Our results demonstrated that (1) the DA affected the EEG signal in the spatiotemporal domain; (2) ADA was able to completely remove the DA without affecting the TEP waveforms; (3). ICA corrections produced significant changes in peak-to-peak TEP amplitude.
CONCLUSIONS:
ADA is a reliable solution for the DA correction, especially considering that (1) it does not affect physiological responses; (2) it is completely data-driven and (3) its effectiveness does not depend on the characteristics of the artefact and on the number of recording electrodes.
SIGNIFICANCE:
We proposed a new reliable algorithm of correction for long-lasting TMS-EEG artifacts
Translation Invariance, Commutation Relations and Ultraviolet/Infrared Mixing
We show that the Ultraviolet/Infrared mixing of noncommutative field theories
with the Gronewold-Moyal product, whereby some (but not all) ultraviolet
divergences become infrared, is a generic feature of translationally invariant
associative products. We find, with an explicit calculation that the phase
appearing in the nonplanar diagrams is the one given by the commutator of the
coordinates, the semiclassical Poisson structure of the non commutative
spacetime. We do this with an explicit calculation for represented generic
products.Comment: 24 pages, 1 figur
Thrust Vector Controller Comparison for a Finless Rocket
The paper focuses on comparing applicability, tuning, and performance of different controllers implemented and tested on a finless rocket during its boost phase. The objective was to evaluate the advantages and disadvantages of each controller, such that the most appropriate one would then be developed and implemented in real-time in the finless rocket. The compared controllers were Linear Quadratic Regulator (LQR), Linear Quadratic Gaussian (LQG), and Proportional Integral Derivative (PID). To control the attitude of the rocket, emphasis is given to the Thrust Vector Control (TVC) component (sub-system) through the gimballing of the rocket engine. The launcher is commanded through the control input thrust gimbal angle δ
, while the output parameter is expressed in terms of the pitch angle θ
. After deriving a linearized state–space model, rocket stability is addressed before controller implementation and testing. The comparative study showed that both LQR and LQG track pitch angle changes rapidly, thus providing efficient closed-loop dynamic tracking. Tuning of the LQR controller, through the Q and R weighting matrices, illustrates how variations directly affect performance of the closed-loop system by varying the values of the feedback gain (K). The LQG controller provides a more realistic profile because, in general, not all variables are measurable and available for feedback. However, disturbances affecting the system are better handled and reduced with the PID controller, thus overcoming steady-state errors due to aerodynamic and model uncertainty. Overall controller performance is evaluated in terms of overshoot, settling and rise time, and steady-state error
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