Publications by authors named "Seyyed Ali Ahmadi"

3 Publications

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Semisupervised classification of hyperspectral images with low-rank representation kernel.

J Opt Soc Am A Opt Image Sci Vis 2020 Apr;37(4):606-613

A semisupervised deformed kernel function, using low-rank representation with consideration of local geometrical structure of data, is presented for the classification of hyperspectral images. The proposed method incorporates the wealth of unlabeled information to deal with the limited labeled samples situation as a common case in HSIs applications. The proposed kernel needs to be computed before training the classifier, e.g., a support vector machine, and it relies on combining the standard radial basis function kernel based on labeled information and the low-rank representation kernel obtained using all available (labeled and unlabeled) information. The low-rank representation kernel can overcome the difficulties of clustering methods that are used to construct the kernels such as bagged kernel and multi-scale bagged kernel. The experimental results of two well-known HSIs data sets demonstrate the effectiveness of the proposed method in comparison with cluster kernels obtained using traditional clustering methods and graph learning methods.
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http://dx.doi.org/10.1364/JOSAA.381158DOI Listing
April 2020

Effects of lumbar discectomy on disability and depression in patients with chronic low back pain.

Anesth Pain Med 2011 Jul 1;1(1):20-4. Epub 2011 Jul 1.

Department of Neurosurgery, Tehran University of Medical Sciences, Tehran, IR Iran.

Background: Back pain is one of the most prevalent health problems for which physicians are consulted. Back pain has many economic impacts, such as sickness absences and long-term disability. The prevalence of major depression in patients with chronic low back pain is approximately 3 to 4 times greater than the prevalence rate reported in the general population.

Objectives: This study was designed to evaluate the depression and disability improvement after lumbar discectomy compared with presurgery levels in patients with chronic low back pain and radicular leg pain.

Patients And Methods: One hundred forty-eight patients with chronic low back pain and radicular leg pain were included in this analytic observational study. The study evaluated several main variables, including age; sex; educational level; job; height; weight; and patient history of abortion, leg pain, back pain, smoking, trauma, number of previous pregnancies, driving, long-term sitting, lifting heavy bodies, and disability and depression before and 6 and 12 months after laminectomy.

Results: The depression and disability scores of patients before lumbar discectomy significantly decreased after surgery.

Conclusions: Our results indicate that lumbar discectomy surgery significantly improved depression and disability in patients with chronic herniated discs.
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http://dx.doi.org/10.5812/kowsar.22287523.1529DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4335750PMC
July 2011

Cystic teratoma of the pancreas: a case report.

Ann Saudi Med 2004 May-Jun;24(3):206-9

Department of Surgery, Sina Hospital, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6147936PMC
http://dx.doi.org/10.5144/0256-4947.2004.206DOI Listing
October 2004