433 research outputs found
Pulsed quantum optomechanics
Studying mechanical resonators via radiation pressure offers a rich avenue
for the exploration of quantum mechanical behavior in a macroscopic regime.
However, quantum state preparation and especially quantum state reconstruction
of mechanical oscillators remains a significant challenge. Here we propose a
scheme to realize quantum state tomography, squeezing and state purification of
a mechanical resonator using short optical pulses. The scheme presented allows
observation of mechanical quantum features despite preparation from a thermal
state and is shown to be experimentally feasible using optical microcavities.
Our framework thus provides a promising means to explore the quantum nature of
massive mechanical oscillators and can be applied to other systems such as
trapped ions.Comment: 9 pages, 4 figure
Culturing Pancreatic Islets in Microfluidic Flow Enhances Morphology of the Associated Endothelial Cells
Pancreatic islets are heavily vascularized in vivo with each insulin secreting beta-cell associated with at least one endothelial cell (EC). This structure is maintained immediately post-isolation; however, in culture the ECs slowly deteriorate, losing density and branched morphology. We postulate that this deterioration occurs in the absence of blood flow due to limited diffusion of media inside the tissue. To improve exchange of media inside the tissue, we created a microfluidic device to culture islets in a range of flow-rates. Culturing the islets from C57BL6 mice in this device with media flowing between 1 and 7 ml/24 hr resulted in twice the EC-density and -connected length compared to classically cultured islets. Media containing fluorescent dextran reached the center of islets in the device in a flow-rate-dependant manner consistent with improved penetration. We also observed deterioration of EC morphology using serum free media that was rescued by addition of bovine serum albumin, a known anti-apoptotic signal with limited diffusion in tissue. We further examined the effect of flow on beta-cells showing dampened glucose-stimulated Ca2+-response from cells at the periphery of the islet where fluid shear-stress is greatest. However, we observed normal two-photon NAD(P)H response and insulin secretion from the remainder of the islet. These data reveal the deterioration of islet EC-morphology is in part due to restricted diffusion of serum albumin within the tissue. These data further reveal microfluidic devices as unique platforms to optimize islet culture by introducing intercellular flow to overcome the restricted diffusion of media components
Moderators of the Relationship between Exercise and Mood Changes: Gender, Exertion Level, and Workout Duration
ABSTRACT Although the role of exercise in improving mood is well established, less is known about moderators of this effect, particularly outside of the laboratory. The current study examined the effect of gender, type of exercise, level of exertion, and duration of workout on the exercisemood relationship in a naturalistic setting. One hundred and thirty five participants (64 females) either engaged in weight training (n=52) or cardiovascular (n=83) exercise. Pre-and postexercise assessments of mood were collected and changes in two types of mood, negative mood and exhaustion, were examined. Overall, participants reported improved mood after exercise in both domains. Workout duration and level of exertion significantly moderated the relationship of exercise to mood improvement (i.e., an increase in either corresponded to greater improved mood, ps < 0.05). Overall, women showed more improved mood than men in the domain of exhaustion (p=0.001)
Gender and sustainable livelihoods: linking gendered experiences of environment, community and self
In this essay I explore the economic, social,
environmental and cultural changes taking place in Bolsena,
Italy, where agricultural livelihoods have rapidly
diminished in the last two decades. I examine how gender
dynamics have shifted with the changing values and
livelihoods of Bolsena through three women’s narratives
detailing their gendered experiences of environment,
community and self. I reflect on these changes with Sabrina,
who is engaged in a feminist community-based
organization; Anna, who is running an alternative wine bar;
and Isabella, a jeweler, who is engaged in ecofeminist
practices. My analysis is based on concepts developed by
feminist political ecology: specifically, the theory of rooted
networks from Dianne Rocheleau, Donna Haraway’s concept
of naturecultures (and the work of J. K. Gibson-Graham
on new economic imaginaries emerging from the
politics of place. I aim to think with, reflect upon and
provoke from the ‘‘otherwise’’, taking into account the
lived relations entwining nature and gender. My article
looks at the interconnections of gender, environment and
livelihoods, attentive to the daily needs, embodied interactions
and labours of these three women as part of a
reappropriation, reconstruction and reinvention of Bolsena’s
lifeworld. By listening to the stories of their everyday
lives and struggles, I show the dynamic potential of the
politics of place and the efforts to build diverse economies
and more ethical economic and ecological relationships
based on gender-aware subjectivities and values
Coupling carbon nanotube mechanics to a superconducting circuit
The quantum behaviour of mechanical resonators is a new and emerging field
driven by recent experiments reaching the quantum ground state. The high
frequency, small mass, and large quality-factor of carbon nanotube resonators
make them attractive for quantum nanomechanical applications. A common element
in experiments achieving the resonator ground state is a second quantum system,
such as coherent photons or superconducting device, coupled to the resonators
motion. For nanotubes, however, this is a challenge due to their small size.
Here, we couple a carbon nanoelectromechanical (NEMS) device to a
superconducting circuit. Suspended carbon nanotubes act as both superconducting
junctions and moving elements in a Superconducting Quantum Interference Device
(SQUID). We observe a strong modulation of the flux through the SQUID from
displacements of the nanotube. Incorporating this SQUID into superconducting
resonators and qubits should enable the detection and manipulation of nanotube
mechanical quantum states at the single-phonon level
Patient Centeredness in Electronic Communication: Evaluation of Patient-to-Health Care Team Secure Messaging
BACKGROUND: As information and communication technology is becoming more widely implemented across health care organizations, patient-provider email or asynchronous electronic secure messaging has the potential to support patient-centered communication. Within the medical home model of the Veterans Health Administration (VA), secure messaging is envisioned as a means to enhance access and strengthen the relationships between veterans and their health care team members. However, despite previous studies that have examined the content of electronic messages exchanged between patients and health care providers, less research has focused on the socioemotional aspects of the communication enacted through those messages.
OBJECTIVE: Recognizing the potential of secure messaging to facilitate the goals of patient-centered care, the objectives of this analysis were to not only understand why patients and health care team members exchange secure messages but also to examine the socioemotional tone engendered in these messages.
METHODS: We conducted a cross-sectional coding evaluation of a corpus of secure messages exchanged between patients and health care team members over 6 months at 8 VA facilities. We identified patients whose medical records showed secure messaging threads containing at least 2 messages and compiled a random sample of these threads. Drawing on previous literature regarding the analysis of asynchronous, patient-provider electronic communication, we developed a coding scheme comprising a series of a priori patient and health care team member codes. Three team members tested the scheme on a subset of the messages and then independently coded the sample of messaging threads.
RESULTS: Of the 711 messages coded from the 384 messaging threads, 52.5% (373/711) were sent by patients and 47.5% (338/711) by health care team members. Patient and health care team member messages included logistical content (82.6%, 308/373 vs 89.1%, 301/338), were neutral in tone (70.2%, 262/373 vs 82.0%, 277/338), and respectful in nature (25.7%, 96/373 vs 33.4%, 113/338). Secure messages from health care team members sometimes appeared hurried (25.4%, 86/338) but also displayed friendliness or warmth (18.9%, 64/338) and reassurance or encouragement (18.6%, 63/338). Most patient messages involved either providing or seeking information; however, the majority of health care team member messages involved information provision in response to patient questions.
CONCLUSIONS: This evaluation is an important step toward understanding the content and socioemotional tone that is part of the secure messaging exchanges between patients and health care team members. Our findings were encouraging; however, there are opportunities for improvement. As health care organizations seek to supplement traditional encounters with virtual care, they must reexamine their use of secure messaging, including the patient centeredness of the communication, and the potential for more proactive use by health care team members
Fate specification and tissue-specific cell cycle control of the <i>Caenorhabditis elegans</i> intestine
Coordination between cell fate specification and cell cycle control in multicellular organisms is essential to regulate cell numbers in tissues and organs during development, and its failure may lead to oncogenesis. In mammalian cells, as part of a general cell cycle checkpoint mechanism, the F-box protein β-transducin repeat-containing protein (β-TrCP) and the Skp1/Cul1/F-box complex control the periodic cell cycle fluctuations in abundance of the CDC25A and B phosphatases. Here, we find that the Caenorhabditis elegans β-TrCP orthologue LIN-23 regulates a progressive decline of CDC-25.1 abundance over several embryonic cell cycles and specifies cell number of one tissue, the embryonic intestine. The negative regulation of CDC-25.1 abundance by LIN-23 may be developmentally controlled because CDC-25.1 accumulates over time within the developing germline, where LIN-23 is also present. Concurrent with the destabilization of CDC-25.1, LIN-23 displays a spatially dynamic behavior in the embryo, periodically entering a nuclear compartment where CDC-25.1 is abundant
Critical Role of Gap Junction Coupled K(ATP) Channel Activity for Regulated Insulin Secretion
Pancreatic β-cells secrete insulin in response to closure of ATP-sensitive K(+) (K(ATP)) channels, which causes membrane depolarization and a concomitant rise in intracellular Ca(2+) (Ca(i)). In intact islets, β-cells are coupled by gap junctions, which are proposed to synchronize electrical activity and Ca(i) oscillations after exposure to stimulatory glucose (>7 mM). To determine the significance of this coupling in regulating insulin secretion, we examined islets and β-cells from transgenic mice that express zero functional K(ATP) channels in approximately 70% of their β-cells, but normal K(ATP) channel density in the remainder. We found that K(ATP) channel activity from approximately 30% of the β-cells is sufficient to maintain strong glucose dependence of metabolism, Ca(i), membrane potential, and insulin secretion from intact islets, but that glucose dependence is lost in isolated transgenic cells. Further, inhibition of gap junctions caused loss of glucose sensitivity specifically in transgenic islets. These data demonstrate a critical role of gap junctional coupling of K(ATP) channel activity in control of membrane potential across the islet. Control via coupling lessens the effects of cell–cell variation and provides resistance to defects in excitability that would otherwise lead to a profound diabetic state, such as occurs in persistent neonatal diabetes mellitus
Quantum nondemolition measurement of mechanical motion quanta
The fields of opto- and electromechanics have facilitated numerous advances
in the areas of precision measurement and sensing, ultimately driving the
studies of mechanical systems into the quantum regime. To date, however, the
quantization of the mechanical motion and the associated quantum jumps between
phonon states remains elusive. For optomechanical systems, the coupling to the
environment was shown to preclude the detection of the mechanical mode
occupation, unless strong single photon optomechanical coupling is achieved.
Here, we propose and analyse an electromechanical setup, which allows to
overcome this limitation and resolve the energy levels of a mechanical
oscillator. We find that the heating of the membrane, caused by the interaction
with the environment and unwanted couplings, can be suppressed for carefully
designed electromechanical systems. The results suggest that phonon number
measurement is within reach for modern electromechanical setups.Comment: 8 pages, 5 figures plus 24 pages, 11 figures supplemental materia
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