674 research outputs found
Optimal control for one-qubit quantum sensing
Quantum systems can be exquisite sensors thanks to their sensitivity to
external perturbations. This same characteristic also makes them fragile to
external noise. Quantum control can tackle the challenge of protecting quantum
sensors from environmental noise, while leaving their strong coupling to the
target field to be measured. As the compromise between these two conflicting
requirements does not always have an intuitive solution, optimal control based
on numerical search could prove very effective. Here we adapt optimal control
theory to the quantum sensing scenario, by introducing a cost function that,
unlike the usual fidelity of operation, correctly takes into account both the
unknown field to be measured and the environmental noise. We experimentally
implement this novel control paradigm using a Nitrogen Vacancy center in
diamond, finding improved sensitivity to a broad set of time varying fields.
The demonstrated robustness and efficiency of the numerical optimization, as
well as the sensitivity advantaged it bestows, will prove beneficial to many
quantum sensing applications
Postprocessing Neuroimaging methods in MRI and PET/MRI with applications to Multiple Sclerosis and other Neurological diseases
Many non-invasive imaging instruments have been developed in the last 40 years, allowing to obtain images of the interior human body while the patient is still alive. In the contest of Neurology studies, imaging system as CT, MRI, SPECT or PET allows to obtain biomarkers useful to quantitatively distinguish between healthy and unhealthy subjects, evaluate the staging of a Neurological illness in a patient, evaluate the efficacy of a treatment, explore the causes of the illness.
In this work MRI and PET imaging system introduced from scratch, going from reconstruction from raw data to state-of-the art post-processing techniques and the computation of more popular biomarkers.
After these introduction, three original work using the recent PET/MRI imaging system are presented, with a particular focus on the methods. These three studies involve patients with Multiple Sclerosis, Alzheimer's Disease and Brain Tumor
Multidisciplinary analysis for unravelling physical and chemical signatures of tectonic deformation processes
The Upper Tiber Valley area presents a compelling seismotectonic setting, with
many open questions to be investigated, along with an optimal scientific background
and monitoring environment to study such topics with a broad perspective and a
high level of detail. The complex seismotectonic setting of the Northern Apennines
offers a unique and large combination of ingredients, all potentially showing key
signatures of the earthquake’s nucleation and preparatory phases. Here there is
a constant and high rate of microseismic release, evidence of fluids overpressure
at depth, well- and mis-oriented normal faults (respect to the regional extensional
stress field), marks of seismic and aseismic activity along them and a state-of-the-art
multidisciplinary network monitoring all these components at high resolution in an
area whose lithological distribution in 3D is very well constrained. Thus, here there
is the potential to investigate a wide range of key topics in modern seismology and
fault mechanics, by the integration of seismic with non-seismic data.
That is why this thesis is based on the idea that the joint analysis of all
this information can contribute to shed light on earthquake initiation and the
mechanisms driving the recurrence and evolution of the seismic sequences. The
main questions that I intend to investigate concern signals of various nature andform that can possibly be detected and traced back to tectonic and seismic processes,
giving hints on the driving mechanisms. Are there detectable signals/anomalies
linkable to seismic activity in the heterogeneous time series recorded by the multi-
parametric instrumentation present in NFOs? If so, what are the relations with local
earthquakes and between different datasets? How to compare the heterogeneous
time series? And more: what is the role of crustal fluids in the seismic sequences of
the area? Are there any identifiable seismic patterns that suggest such interactions?
Do local earthquakes nucleate independently of lithology or are some layers more
prone to trigger seismicity? These questions are addressed in the main chapters of
the thesis, the structure of which is reported in the following
Student responses to an animated character in information literacy instruction
Purpose: This paper reports on a grant-funded project to create a hand-drawn, custom-made animated character named Jasmyn. Drawing on animation theory, the paper uses qualitative research to investigate student responses to the medium of animation, the character’s design, and three presentation strategies.
Design/methodology/approach: The researchers held three student focus groups to investigate the following research questions: 1. Will students endorse animation as a medium for library instructional videos on the grounds of its entertaining, subversive, or playful qualities? 2. Is Jasmyn designed and8 written in a way that engages students and compels them to respond to her as a character? 3. How will students respond to three presentation strategies: a lecture-style video, a video with supplemental animations, and a real-time, interactive lesson.
Findings: The researchers found that students expressed broad enthusiasm for animation as a medium, though responses to Jasmyn’s personality were mixed. The only presentation strategy that prompted unique responses was the interactive session, although though all three focus groups provided revealing commentary about online learning. Students also identified aspects of the animation and character that could be improved, and reflected on ways Jasmyn might be integrated into online learning.
Research limitations/implications: This study, performed as part of a pilot project, was deliberately small in scale. Clearer implications would emerge from repetition with a larger group of students.
Originality/value: Jasmyn may be the only hand-drawn, custom-made animated character created for library instruction. No research studies on the use of animation in libraries have been published to date
Noise spectroscopy of a quantum-classical environment with a diamond qubit
Knowing a quantum system's environment is critical for its practical use as a
quantum device. Qubit sensors can reconstruct the noise spectral density of a
classical bath, provided long enough coherence time. Here we present a protocol
that can unravel the characteristics of a more complex environment, comprising
both unknown coherently coupled quantum systems, and a larger quantum bath that
can be modeled as a classical stochastic field. We exploit the rich environment
of a Nitrogen-Vacancy center in diamond, tuning the environment behavior with a
bias magnetic field, to experimentally demonstrate our method. We show how to
reconstruct the noise spectral density even when limited by relatively short
coherence times, and identify the local spin environment. Importantly, we
demonstrate that the reconstructed model can have predictive power, describing
the spin qubit dynamics under control sequences not used for noise
spectroscopy, a feature critical for building robust quantum devices. At lower
bias fields, where the effects of the quantum nature of the bath are more
pronounced, we find that more than a single classical noise model are needed to
properly describe the spin coherence under different controls, due to the back
action of the qubit onto the bath.Comment: Main text: 5 pages, 5 figures. Supplemental material: 7 pages, 7
figures, 4 table
Comics to the Rescue: Finding Innovative Applications for Library Digital Learning Objects
When faculty were asked to use online assignments to make up the class time lost due to Hurricane Sandy, librarians at Lehman College\u27s Leonard Lief Library spotted a new opportunity for the Library\u27s Web comics. This article describes the partnership between the Library and the College\u27s Art Department that led to the development of the Web comics, provides readers with a model for responding to circumstances creatively, and puts forward an approach for combining digital learning objects with writing assignments to meet faculty needs
A Low-Hassle, Low-Cost Method to Survey Student Attitudes about Library Space
This article discusses how two members of the space planning committee at Lehman College library created a brief paper survey, distributed it to students in the library, and designed a Google spreadsheet to enable the committee to work as a group to compile results. We provide our survey tool as an example; explain how we simplified data compilation through a “quick and dirty” coding process; outline step-by-step instructions on how to design a Google spreadsheet that enables many librarians to input survey results consistently; and describe our mistakes and “lessons learned.” We believe our practical approach could be easily implemented as a space planning tool in any number of libraries—even those with small staffs and budgets
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