Four-channel optically pumped magnetometer for a magnetoencephalography sensor array.

We present a novel four-channel optically pumped magnetometer (OPM) for magnetoencephalography that utilizes a two-color pump/probe scheme on a single optical axis. We characterize its performance across 18 built sensor modules. The new sensor implements several improvements over our previously developed sensor including lower vapor-cell operating temperature, improved probe-light detection optics, and reduced optical power requirements. The sensor also has new electromagnetic field coils on the sensor head which are designed using stream-function-based current optimization. We detail the coil design methodology and present experimental characterization of the coil performance. The magnetic sensitivity of the sensor is on average 12.3 fT/rt-Hz across the 18 modules while the average gradiometrically inferred sensitivity is about 6.0 fT/rt-Hz. The sensor 3-dB bandwidth is 100 Hz on average. The on-sensor coil performance is in good agreement with the simulations.

Single-trial classification of evoked responses to auditory tones using OPM- and SQUID-MEG.

Objective.Optically pumped magnetometers (OPMs) are emerging as a near-room-temperature alternative to superconducting quantum interference devices (SQUIDs) for magnetoencephalography (MEG). In contrast to SQUIDs, OPMs can be placed in a close proximity to subject's scalp potentially increasing the signal-to-noise ratio and spatial resolution of MEG. However, experimental demonstrations of these suggested benefits are still scarce. Here, to compare a 24-channel OPM-MEG system to a commercial whole-head SQUID system in a data-driven way, we quantified their performance in classifying single-trial evoked responses.Approach.We measured evoked responses to three auditory tones in six participants using both OPM- and SQUID-MEG systems. We performed pairwise temporal classification of the single-trial responses with linear discriminant analysis as well as multiclass classification with both EEGNet convolutional neural network and xDAWN decoding.Main results.OPMs provided higher classification accuracies than SQUIDs having a similar coverage of the left hemisphere of the participant. However, the SQUID sensors covering the whole helmet had classification scores larger than those of OPMs for two of the tone pairs, demonstrating the benefits of a whole-head measurement.Significance.The results demonstrate that the current OPM-MEG system provides high-quality data about the brain with room for improvement for high bandwidth non-invasive brain-computer interfacing.

A Four-channel Optically Pumped Magnetometer for a Magnetoencephalography Sensor Array.

We present a novel four-channel OPM sensor for magnetoencephalography that utilizes a two-color pump/probe scheme on a single optical axis. We characterize its performance across 18 built sensor modules. The new sensor implements several improvements over our previously developed sensor including lower vapor-cell operating temperature, improved probe-light detection optics, and reduced optical power requirements. The sensor also has new electromagnetic field coils on the sensor head which are designed using stream-function-based current optimization. We detail the coil design methodology and present experimental characterization of the coil performance. The magnetic sensitivity of the sensor is on average 12.3 fT/rt-Hz across the 18 modules while the average gradiometrically inferred sensitivity is about 6.0 fT/rt-Hz. The sensor 3-dB bandwidth is 100 Hz on average. The on-sensor coil performance is in good agreement with the simulations.

Calibration and Localization of Optically Pumped Magnetometers Using Electromagnetic Coils.

In this paper, we propose a method to estimate the position, orientation, and gain of a magnetic field sensor using a set of (large) electromagnetic coils. We apply the method for calibrating an array of optically pumped magnetometers (OPMs) for magnetoencephalography (MEG). We first measure the magnetic fields of the coils at multiple known positions using a well-calibrated triaxial magnetometer, and model these discreetly sampled fields using vector spherical harmonics (VSH) functions. We then localize and calibrate an OPM by minimizing the sum of squared errors between the model signals and the OPM responses to the coil fields. We show that by using homogeneous and first-order gradient fields, the OPM sensor parameters (gain, position, and orientation) can be obtained from a set of linear equations with pseudo-inverses of two matrices. The currents that should be applied to the coils for approximating these low-order field components can be determined based on the VSH models. Computationally simple initial estimates of the OPM sensor parameters follow. As a first test of the method, we placed a fluxgate magnetometer at multiple positions and estimated the RMS position, orientation, and gain errors of the method to be 1.0 mm, 0.2°, and 0.8%, respectively. Lastly, we calibrated a 48-channel OPM array. The accuracy of the OPM calibration was tested by using the OPM array to localize magnetic dipoles in a phantom, which resulted in an average dipole position error of 3.3 mm. The results demonstrate the feasibility of using electromagnetic coils to calibrate and localize OPMs for MEG.

Cross-Axis projection error in optically pumped magnetometers and its implication for magnetoencephalography systems.

Optically pumped magnetometers (OPMs) developed for magnetoencephalography (MEG) typically operate in the spin-exchange-relaxation-free (SERF) regime and measure a magnetic field component perpendicular to the propagation axis of the optical-pumping photons. The most common type of OPM for MEG employs alkali atoms, e.g. 87Rb, as the sensing element and one or more lasers for preparation and interrogation of the magnetically sensitive states of the alkali atoms ensemble. The sensitivity of the OPM can be greatly enhanced by operating it in the SERF regime, where the alkali atoms' spin exchange rate is much faster than the Larmor precession frequency. The SERF regime accommodates remnant static magnetic fields up to ±5 nT. However, in the presented work, through simulation and experiment, we demonstrate that multi-axis magnetic signals in the presence of small remnant static magnetic fields, not violating the SERF criteria, can introduce significant error terms in OPM's output signal. We call these deterministic errors cross-axis projection errors (CAPE), where magnetic field components of the MEG signal perpendicular to the nominal sensing axis contribute to the OPM signal giving rise to substantial amplitude and phase errors. Furthermore, through simulation, we have discovered that CAPE can degrade localization and calibration accuracy of OPM-based magnetoencephalography (OPM-MEG) systems.

Non-Invasive Functional-Brain-Imaging with an OPM-based Magnetoencephalography System.

A non-invasive functional-brain-imaging system based on optically-pumped-magnetometers (OPM) is presented. The OPM-based magnetoencephalography (MEG) system features 20 OPM channels conforming to the subject's scalp. We have conducted two MEG experiments on three subjects: assessment of somatosensory evoked magnetic field (SEF) and auditory evoked magnetic field (AEF) using our OPM-based MEG system and a commercial MEG system based on superconducting quantum interference devices (SQUIDs). We cross validated the robustness of our system by calculating the distance between the location of the equivalent current dipole (ECD) yielded by our OPM-based MEG system and the ECD location calculated by the commercial SQUID-based MEG system. We achieved sub-centimeter accuracy for both SEF and AEF responses in all three subjects. Due to the proximity (12 mm) of the OPM channels to the scalp, it is anticipated that future OPM-based MEG systems will offer enhanced spatial resolution as they will capture finer spatial features compared to traditional MEG systems employing SQUIDs.

Magnetic Source Imaging Using a Pulsed Optically Pumped Magnetometer Array.

We have developed a pulsed optically pumped magnetometer (OPM) array for detecting magnetic field maps originated from an arbitrary current distribution. The presented magnetic source imaging (MSI) system features 24 OPM channels, has a data rate of 500 S/s, a sensitivity of 0.8 p T / H z , and a dynamic range of 72 dB. We have employed our pulsed- OPM MSI system for measuring the magnetic field map of a test coil structure. The coils are moved across the array in an indexed fashion to measure the magnetic field over an area larger than the array. The captured magnetic field maps show excellent agreement with the simulation results. Assuming a 2D current distribution, we have solved the inverse problem, using the measured magnetic field maps, and the reconstructed current distribution image is compared to that of the simulation.

A 20-channel magnetoencephalography system based on optically pumped magnetometers.

We describe a multichannel magnetoencephalography (MEG) system that uses optically pumped magnetometers (OPMs) to sense the magnetic fields of the human brain. The system consists of an array of 20 OPM channels conforming to the human subject's head, a person-sized magnetic shield containing the array and the human subject, a laser system to drive the OPM array, and various control and data acquisition systems. We conducted two MEG experiments: auditory evoked magnetic field and somatosensory evoked magnetic field, on three healthy male subjects, using both our OPM array and a 306-channel Elekta-Neuromag superconducting quantum interference device (SQUID) MEG system. The described OPM array measures the tangential components of the magnetic field as opposed to the radial component measured by most SQUID-based MEG systems. Herein, we compare the results of the OPM- and SQUID-based MEG systems on the auditory and somatosensory data recorded in the same individuals on both systems.

Four-channel optically pumped atomic magnetometer for magnetoencephalography.

We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. This module will serve as a building block of an array for magnetic source localization.

Risk and uncertainty.

Volatile business conditions have led to drastic corporate downsizing, meaning organizations are expected to do more with less. Managers must be more knowledgeable and possess a more eclectic myriad of business skills, many of which have not even been seen until recently. Many internal and external changes have occurred to organizations that have dictated the need to do business differently. Changes such as technological advances; globalization; catastrophic business crises; a more frantic competitive climate; and more demanding, sophisticated customers are examples of some of the shifts in the external business environment. Internal changes to organizations have been in the form of reengineering, accompanied by structural realignments and downsizing; greater emphasis on quality levels in product and service output; faster communication channels; and a more educated, skilled employee base with higher expectations from management.

Leadership and management performance.

Of all the things managers perform to develop employees, many people believe the most important one is leadership. Leadership is defined as using skills, experience, and direction to help someone improve their performance. Leadership consists primarily of giving people feedback to reinforce what they do well while suggesting ways and means to improve. It implies that everybody can improve and it is hoped that everybody wants to get better at what they do.

Health insurance and corporate social responsibility.

Innovation drives productivity in the nonprofit sector as well as in the commercial sector. The greatest advances come not from incremental improvements in efficiency but from new and better approaches. The most powerful way to create social value, therefore, is by developing a new means to address social problems and putting it into widespread practice. The expertise, research capacity, and reach that companies bring to philanthropy can help nonprofits create new solutions that they could never afford to develop on their own. Corporate managers sometimes work directly with faculty and community residents to implement local business projects. These projects often have significant societal benefits, especially since student collaboration and involvement extend to communities in many different inner cities. These projects are incredibly diverse and through such initiatives, management education not only provides an educationally rewarding outlet for students but also endows and enriches inner city communities. Management students sometimes work directly with faculty and community residents to implement local business projects. These projects often have significant societal benefits, especially since student collaboration and involvement extend to communities in many different inner cities. These projects are incredibly diverse and through such initiatives, management education not only provides an educationally rewarding outlet for students but also endows and enriches inner city communities. This article looks at how to use corporate social responsibility and service learning to drive innovation for local inner-city economic development.

Managing retention.

To build this process it is necessary to consult customers for preferences, build familiarity and knowledge to build a relationship and conduct business in a customized fashion. The process takes every opportunity to build customer satisfaction with each customer contact. It is an important process to have, since customers today are more demanding, sophisticated, educated and comfortable speaking to the company as an equal (Belk, 2003). Customers have more customized expectations so they want to be reached as individuals (Raymond and Tanner, 1994). Also, a disproportionate search for new business is costly. The cost to cultivate new customers is more than maintaining existing customers (Cathcart, 1990). Other reasons that customer retention is necessary is because many unhappy customers will never buy again from a company that dissatisfied them and they will communicate their displeasure to other people. These dissatisfied customers may not even convey their displeasure but without saying anything just stop doing business with that company, which may keep them unaware for some time that there is any problem (Cathcart, 1990).

Sales management coaching: a model for improved insurance company performance.

Of all the things sales managers do to develop salespeople, many people believe the most important one is coaching. Coaching is defined as using skills, experience, and direction to help someone improve their performance. Coaching consists primarily of giving people feedback to reinforce what they do well while suggesting ways and means to improve. Coaching implies that everybody can improve and hopefully everybody wants to get better at what they do. Many sales managers erroneously believe that they have to be better than the person they are coaching at the skill set they are discussing in order to be a useful coaching resource to that person. To be a good coach requires an understanding of the skills being discussed and a desire to help someone improve in the performance of their job. The sales manager who knows how to provide that feedback will have more productive, effective, satisfied, and motivated salespeople. This paper provides an overview of the coaching sequence and the skills required to make it work with some comment on how this was successfully applied to a major national insurance company. Sales Management styles vary, and what works for one person may not work for another. Effective Sales Management Coaching can provide sales managers with the skills to help salespeople grow and develop professionally.

Another look at the relationship between socioeconomic factors and the black-white health benefit inequality.

This paper illustrates the black-white disparity in health benefit coverage and the socioeconomic variables-unemployment, income, and education. The health benefit disparity is strongly related to the disparity in underlying socioeconomic variables. Moreover, the time-series examination reveals that the change in white workers' health insurance coverage is largely determined by its year-to-year persistence and the labor market tightness (or the business cycle), while that of black workers is largely determined by the change in their earnings with a slight persistence. The effect of the change in annual earnings seems to dominate the effect of the labor market condition (unemployment rate) and other variables. Finally, although marginally significant, an increase in the attainment of higher education (college) has a positive effect on the black-white health benefit disparity.

Insurance coverage with Aon after September 11, 2001.

Today it is important for hospital organizations to understand the implications of insurance dealings. After September 11, 2001 the insurance industry had an impact on hospitals and health care organizations. This article looks at Aon Insurance and how they handled this situation.