| 1. |
- Abdallah, Nancy, et al.
(författare)
-
Lefschetz properties of some codimension three Artinian Gorenstein algebras
- 2023
-
Ingår i: Journal of Algebra. - : Elsevier BV. - 0021-8693 .- 1090-266X. ; 625, s. 28-45
-
Tidskriftsartikel (refereegranskat)abstract
- Codimension two Artinian algebras have the strong and weak Lefschetz properties provided the characteristic is zero or greater than the socle degree. It is open to what extent such results might extend to codimension three Artinian Gorenstein algebras. Despite much work, the strong Lefschetz property for codimension three Artinian Gorenstein algebra has remained largely mysterious; our results build on and strengthen some of the previous results. We here show that every standard-graded codimension three Artinian Gorenstein algebra A having maximum value of the Hilbert function at most six has the strong Lefschetz property, provided that the characteristic is zero. When the characteristic is greater than the socle degree of A, we show that A is almost strong Lefschetz, they are strong Lefschetz except in the extremal pair of degrees.
|
|
| 2. |
|
|
| 3. |
- Abtahi, Farhad, 1981-, et al.
(författare)
-
An Affordable ECG and Respiration Monitoring System Based on Raspberry PI and ADAS1000 : First Step towards Homecare Applications
- 2015
-
Ingår i: 16th Nordic-Baltic Conference on Biomedical Engineering. - Cham : Springer. - 9783319129662 ; , s. 5-8, s. 5-8
-
Konferensbidrag (refereegranskat)abstract
- Homecare is a potential solution for problems associated with an aging population. This may involve several physiological measurements, and hence a flexible but affordable measurement device is needed. In this work, we have designed an ADAS1000-based four-lead electrocardiogram (ECG) and respiration monitoring system. It has been implemented using Raspberry PI as a platform for homecare applications. ADuM chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 and IEC 60950 for patient safety. The result proved the potential of Raspberry PI for the design of a compact, affordable, and medically safe measurement device. Further work involves developing a more flexible software for collecting measurements from different devices (measuring, e.g., blood pressure, weight, impedance spectroscopy, blood glucose) through Bluetooth or user input and integrating them into a cloud-based homecare system.
|
|
| 4. |
- Abtahi, Farhad, et al.
(författare)
-
Biosignal PI, an Affordable Open-Source ECG and Respiration Measurement System
- 2014
-
Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 15:1, s. 93-109
-
Tidskriftsartikel (refereegranskat)abstract
- Bioimedical pilot projects e.g., telemedicine, homecare, animal and human trials usually involve several physiological measurements. Technical development of these projects is time consuming and in particular costly. A versatile but affordable biosignal measurement platform can help to reduce time and risk while keeping the focus on the important goal and making an efficient use of resources. In this work, an affordable and open source platform for development of physiological signals is proposed. As a first step an 8–12 leads electrocardiogram (ECG) and respiration monitoring system is developed. Chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 for patient safety. The result shows the potential of this platform as a base for prototyping compact, affordable, and medically safe measurement systems. Further work involves both hardware and software development to develop modules. These modules may require development of front-ends for other biosignals or just collect data wirelessly from different devices e.g., blood pressure, weight, bioimpedance spectrum, blood glucose, e.g., through Bluetooth. All design and development documents, files and source codes will be available for non-commercial use through project website, BiosignalPI.org.
|
|
| 5. |
- Abtahi, Farhad, 1981-, et al.
(författare)
-
Development and preliminary evaluation of an Android based heart rate variability biofeedback system
- 2014
-
Ingår i: Engineering in Medicine and Biology Society (EMBC), 2014 36th Annual International Conference of the IEEE. - : IEEE. - 9781424479290 ; 2014, s. 3382-5
-
Konferensbidrag (refereegranskat)abstract
- The reduced Heart Rate Variability (HRV) is believed to be associated with several diseases such as congestive heart failure, diabetes and chronic kidney diseases (CKD). In these cases, HRV biofeedback may be a potential intervention method to increase HRV which in turn is beneficial to these patients. In this work, a real-time Android biofeedback application based on a Bluetooth enabled ECG and thoracic electrical bioimpedance (respiration) measurement device has been developed. The system performance and usability have been evaluated in a brief study with eight healthy volunteers. The result demonstrates real-time performance of system and positive effects of biofeedback training session by increased HRV and reduced heart rate. Further development of the application and training protocol is ongoing to investigate duration of training session to find an optimum length and interval of biofeedback sessions to use in potential interventions.
|
|
| 6. |
- Abtahi, Farhad, et al.
(författare)
-
Electrical bioimpedance spectroscopy in time-variant systems : Is undersampling always a problem?
- 2014
-
Ingår i: Journal of Electrical Bioimpedance. - : Walter de Gruyter GmbH. - 1891-5469. ; 5:1, s. 28-33
-
Tidskriftsartikel (refereegranskat)abstract
- During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied mainly by using the frequency-sweep technique, across a range of many different applications. Traditionally, the tissue under study is considered to be time-invariant and dynamic changes of tissue activity are ignored by treating the changes as a noise source. A new trend in EBIS is simultaneous electrical stimulation with several frequencies, through the application of a multi-sine, rectangular or other waveform. This method can provide measurements fast enough to sample dynamic changes of different tissues, such as cardiac muscle. This high sampling rate comes at a price of reduction in SNR and the increase in complexity of devices. Although the frequency-sweep technique is often inadequate for monitoring the dynamic changes in a variant system, it can be used successfully in applications focused on the time-invariant or slowly-variant part of a system. However, in order to successfully use frequency-sweep EBIS for monitoring time-variant systems, it is paramount to consider the effects of aliasing and especially the folding of higher frequencies, on the desired frequency e.g. DC level. This paper discusses sub-Nyquist sampling of thoracic EBIS measurements and its application in the case of monitoring pulmonary oedema. It is concluded that by considering aliasing, and with proper implementation of smoothing filters, as well as by using random sampling, frequency-sweep EBIS can be used for assessing time-invariant or slowly-variant properties of time-variant biological systems, even in the presence of aliasing. In general, undersampling is not always a problem, but does always require proper consideration.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Abtahi, Farhad, 1981-, et al.
(författare)
-
Wearable Sensors Enabling Personalized Occupational Healthcare
- 2018
-
Ingår i: Intelligent Environments 2018. - Amsterdam : IOS Press. - 9781614998730 - 9781614998747 ; , s. 371-376
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents needs and potentials for wearable sensors inoccupational healthcare. In addition, it presents ongoing European and Swedishprojects for developing personalized, and pervasive wearable systems for assessingrisks of developing musculoskeletal disorders and cardiovascular diseases at work.Occupational healthcare should benefit in preventing diseases and disorders byproviding the right feedback at the right time to the right person. Collected datafrom workers can provide evidence supporting the ergonomic and industrial tasksof redesigning the working environment to reduce the risks.
|
|
