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1.
Pain Pract ; 2024 Mar 30.
Article in English | MEDLINE | ID: mdl-38553945

ABSTRACT

INTRODUCTION: The Accreditation Council for Graduate Medical Education (ACGME) approved the first pain medicine fellowship programs over three decades ago, designed around a pharmacological philosophy. Following that, there has been a rise in the transition of pain medicine education toward a multidisciplinary interventional model based on a tremendous surge of contemporaneous literature in these areas. This trend has created variability in clinical experience and education amongst accredited pain medicine programs with minimal literature evaluating the differences and commonalities in education and experience of different pain medicine fellowships through Program Director (PD) experiences. This study aims to gather insight from pain medicine fellowship program directors across the country to assess clinical and interventional training, providing valuable perspectives on the future of pain medicine education. METHODS: This study involved 56 PDs of ACGME-accredited pain fellowship programs in the United States. The recruitment process included three phases: advanced notification, invitation, and follow-up to maximize response rate. Participants completed a standard online questionnaire, covering various topics such as subcategory fields, online platforms for supplemental education, clinical experience, postgraduate practice success, and training adequacy. RESULTS: Surveys were completed by 39/56 (69%) standing members of the Association of Pain Program Directors (APPD). All PDs allowed fellows to participate in industry-related and professional society-related procedural workshops, with 59% encouraging these workshops. PDs emphasized the importance of integrity, professionalism, and diligence for long-term success. Fifty-four percent of PDs expressed the need for extension of fellowship training to avoid supplemental education by industry or pain/spine societies. CONCLUSION: This study highlights the challenge of providing adequate training in all Pain Medicine subtopics within a 12-month pain medicine fellowship. PDs suggest the need for additional training for fellows and discuss the importance of curriculum standardization.

4.
J Neurosurg Anesthesiol ; 35(1): 80-85, 2023 Jan 01.
Article in English | MEDLINE | ID: mdl-34469414

ABSTRACT

BACKGROUND: Perioperative opioids are problematic following craniotomy as they can impede neurological examination because of excessive sedation and mask surgical complications. Multimodal anesthetic techniques including nerve blocks have been used successfully to deliver opioid-free anesthesia in other surgical populations; however, no clinical data evaluating opioid-free anesthesia for craniotomy exists within the current body of literature. MATERIALS AND METHODS: Six prospectively identified patients underwent supratentorial craniotomy at Emory University Hospital using a multimodal opioid-free anesthetic (OFA) technique consisting of preoperative scalp block, dexmedetomidine and intravenous acetaminophen. These opioid-free patients were matched by age, sex, incision length, and incision location to 18 retrospectively identified control patients who underwent craniotomy using conventional, opioid-based anesthetic techniques. Postoperative opioid consumption and pain scores were compared and analyzed for noninferiority. RESULTS: Noninferiority of the OFA technique was demonstrated for opioid consumption at all measured intervals from postanesthesia care unit arrival to 24 hours postoperatively. Noninferiority was also demonstrated with respect to average postoperative pain scores from 0 to 12 hours, 0 to 24 hours, as well as length of postanesthesia care unit stay. Noninferiority was not shown for time to first rescue opioid postoperatively, pain scores for the 12 to 24 hours postoperative period, or time to emergence from anesthesia. CONCLUSIONS: This pilot study demonstrates the feasibility of an OFA technique for patients undergoing supratentorial craniotomy and suggests that larger prospective randomized controlled trials are indicated to examine the role of multimodal anesthetic techniques for craniotomy.


Subject(s)
Nerve Block , Humans , Pilot Projects , Prospective Studies , Retrospective Studies , Analgesics, Opioid/therapeutic use , Craniotomy , Pain, Postoperative/drug therapy
5.
Pain Physician ; 25(2): 125-130, 2022 03.
Article in English | MEDLINE | ID: mdl-35322966

ABSTRACT

BACKGROUND: The COVID-19 pandemic ushered in a shift to a video format for pain medicine fellowship interviews for the 2021-2022 academic year, which represented a major change in the fellowship interview paradigm. OBJECTIVES: Our aim was to assess the experience of a video-only format in place of in-person interviews for Pain Medicine fellowship program directors and applicants after the 2020 fellowship interview season to determine the feasibility for continuation beyond COVID-19 travel restrictions. STUDY DESIGN: Survey via Qualtrics. SETTING: Academic pain medicine programs. METHODS: A consortium of program directors converged to discuss methods for determining the effectiveness and future direction of the video format for pain medicine fellowship interviews. Two surveys were formulated, one targeting pain medicine fellowship program directors and the other for candidates interviewing for the year 2021-2022. RESULTS: For applicants, 55 out of 170 responded for a response rate of 32.3%, and for program directors, 38 out of 95 responded for a response rate of 40%. Of the applicants, 45.7% stated that they would prefer video interviews, whereas 27.3% of program directors preferred video interviews. Savings of time and money were the most common reason for preferring video interviews. LIMITATIONS: The number of pain fellowship applicants invited was limited to those who interviewed at a subset of pain fellowships, which may not have been representative of all pain fellow applicants. CONCLUSIONS: The video format for pain medicine fellowship interviews was viewed positively by both candidates and program directors. We suspect that the video format alone or as a part of a hybrid model will become a routine method for the interview process in the future, given its time and cost benefits.


Subject(s)
COVID-19 , Fellowships and Scholarships , Humans , Pain , Pandemics , Surveys and Questionnaires
6.
Pharmacotherapy ; 42(4): 298-310, 2022 04.
Article in English | MEDLINE | ID: mdl-35146776

ABSTRACT

STUDY OBJECTIVE: The objective of our study was to determine safety and pharmacology (pharmacokinetics and preliminary efficacy) of intranasal (IN) ketamine for uncontrolled cancer-related pain. DESIGN: Dose escalation clinical trial. SETTING: Outpatient. PATIENTS: Ten adult patients with uncontrolled cancer-related pain. INTERVENTION: Each patient received escalating doses of ketamine over four visits, each 2-5 days apart: 10 mg IN at visit 1, 10 mg intravenous (IV) at visit 2, 30 mg IN at visit 3, and 50 mg IN at visit 4. MEASUREMENTS: Pain was measured before and after drug administration for up to 4 h using the 11 point (0-10) Numerical Pain Rating Scale (NPRS). MAIN RESULTS: All subjects had advanced cancer, with intractable pain, despite being on moderate dosage of opioids. There was a statistically significant reduction in median NPRS by 1.5 (1-4), 3 (2-3), and 4 (3-5) points at 60 min after receiving the medication and remained decreased by 1.5 (1-2), 2 (1-2) and 1 (1-4) points at the end of the study visit (240 min) with the 10 mg, 30 mg and 50 mg IN dosage, respectively. The median percentage of maximal pain relief being 22.5 (16.6-71.5), 65.5 (40-100), and 69.25 (50-100) for 10 mg, 30 mg and 50 mg IN dosage, respectively and 100 (75-100) with 10 mg IV dose. All side effects (nausea and feeling of unreality) resolved by the end of each study visit. No severe adverse events occurred. CONCLUSION: In this single-institution study, all dosages of IN ketamine administered in the study (10, 30, and 50 mg) provided significant pain relief for intractable cancer-related pain and were well tolerated. The 50 mg dose provided maximal pain relief without major side effects. Further study focused on repeated administration efficacy and safety for cancer-related pain is warranted.


Subject(s)
Cancer Pain , Ketamine , Neoplasms , Adult , Analgesics , Analgesics, Opioid , Cancer Pain/drug therapy , Double-Blind Method , Humans , Ketamine/adverse effects , Neoplasms/chemically induced , Neoplasms/complications , Neoplasms/drug therapy , Pain/drug therapy , Pain/etiology , Pain Measurement , Treatment Outcome
7.
Best Pract Res Clin Anaesthesiol ; 35(3): 307-319, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34511221

ABSTRACT

Telemedicine is the medical practice of caring for and treating patients remotely. With the spread of the coronavirus disease-2019 (COVID-19) pandemic, telemedicine has become increasingly prevalent. Although telemedicine was already in practice before the 2020 pandemic, the internet, smartphones, computers, and video-conferencing tools have made telemedicine easily accessible and available to almost everyone. However, there are also new challenges that health care providers may not be prepared for, including treating and diagnosing patients without physical contact. Physician adoption also depends upon reimbursement and education to improve the telemedicine visits. We review current trends involving telemedicine, how pandemics such as COVID-19 affect the remote treatment of patients, and key concepts important to healthcare providers who practice telemedicine.


Subject(s)
COVID-19/prevention & control , Health Personnel/trends , Practice Patterns, Physicians'/trends , Telemedicine/trends , COVID-19/diagnosis , COVID-19/epidemiology , Humans , Pain Management/methods , Pain Management/trends , Pandemics/prevention & control , Substance-Related Disorders/epidemiology , Substance-Related Disorders/therapy , Telemedicine/methods
9.
Can J Anaesth ; 68(11): 1683-1689, 2021 11.
Article in English | MEDLINE | ID: mdl-34312821

ABSTRACT

BACKGROUND: Stellate ganglion blockade (SGB) has been used to treat electrical storm (ES) refractory to antiarrhythmic therapy or to stabilize patients before more definitive intervention. Nevertheless, its efficacy is not well understood, with only a few case reports and retrospective case series in the literature. METHODS: We conducted a historical cohort study on patients with drug-refractory ES who underwent ultrasound-guided unilateral SGB from 1 January 2010 until 19 July 2019 at two hospital sites. Stellate ganglion blockade was performed with variable combinations of bupivacaine, lidocaine, ropivacaine, and dexamethasone. We collected data on demographic and procedural characteristics, the number of arrhythmias and defibrillation episodes, antiarrhythmic and anticoagulant medication, left ventricular ejection fraction (EF), and respiratory support requirement. RESULTS: We identified N = 13 patients; their mean (standard deviation [SD]) age was 64 (13) yr, and 10 (77%) were male. The baseline mean (SD) number of overall arrhythmia and defibrillation episodes per day were 9 (6) and 4 (3), respectively; the mean (SD) pre-SGB EF was 23 (7)%. Seven patients (54%) received dexamethasone in addition to local anesthetic for SGB. One patient experienced hypotension after SGB. Arrhythmias and defibrillation episodes significantly decreased at 24, 48, 72, and 96 hr after SGB; at 96 hr, 62% and 92% of patients had no VA and defibrillation episodes, respectively (P < 0.001 for all time points). Ejection fraction and the number of patients receiving antiarrhythmic medications or requiring respiratory support were unchanged. CONCLUSIONS: Unilateral SGB was associated with a reduction in arrhythmias and defibrillation episodes, but did not affect antiarrhythmic medication, respiratory support, or EF. Randomized controlled trials on larger cohorts are needed to confirm these findings.


RéSUMé: CONTEXTE: Le bloc du ganglion stellaire (BGS) a été employé pour traiter les tempêtes électriques réfractaires à la thérapie antiarythmique ou pour stabiliser les patients avant une intervention plus définitive. Néanmoins, son efficacité n'est pas bien comprise, et il n'existe que quelques présentations de cas et séries de cas rétrospectives dans la littérature. MéTHODE: Nous avons mené une étude de cohorte historique auprès de patients souffrant de tempêtes électriques réfractaires aux médicaments qui ont subi un BGS unilatéral échoguidé entre le 1er janvier 2010 et le 19 juillet 2019 dans deux sites hospitaliers. Le bloc du ganglion stellaire a été réalisé à l'aide de combinaisons variables de bupivacaïne, de lidocaïne, de ropivacaïne et de dexaméthasone. Nous avons colligé les données touchant aux caractéristiques démographiques et procédurales, au nombre d'arythmies et d'épisodes de défibrillation, aux traitements antiarythmique et anticoagulant, à la fraction d'éjection (FE) ventriculaire gauche, et au besoin d'assistance respiratoire. RéSULTATS: Nous avons identifié N = 13 patients; leur âge moyen (écart type [ÉT]) était de 64 (13) ans, et 10 (77 %) patients étaient des hommes. Globalement, le nombre moyen (ÉT) d'épisodes d'arythmie et de défibrillation de base par jour était de 9 (6) et 4 (3), respectivement; la FE moyenne (ÉT) pré-BGS était de 23 (7) %. Sept patients (54 %) ont reçu de la dexaméthasone en plus de l'anesthésique local pour le BGS. Un patient a souffert d'hypotension après le BGS. Les arythmies et les épisodes de défibrillation ont diminué de manière significative à 24, 48, 72, et 96 heures après le BGS; à 96 heures, 62 % et 92 % des patients ne subissaient plus aucun épisode d'arythmie ventriculaire et de défibrillation, respectivement (P < 0,001 pour tous les temps). La fraction d'éjection et le nombre de patients recevant des médicaments antiarythmiques ou nécessitant une assistance respiratoire sont demeurés inchangés. CONCLUSION: Un BGS unilatéral a été associé à une réduction des épisodes d'arythmies et de défibrillation, mais n'a pas eu d'impact sur le traitement antiarythmique, l'assistance respiratoire, ou la FE. Des études randomisées contrôlées réalisées avec des cohortes plus importantes sont nécessaires pour confirmer ces résultats.


Subject(s)
Autonomic Nerve Block , Tachycardia, Ventricular , Cohort Studies , Humans , Male , Retrospective Studies , Stellate Ganglion , Stroke Volume , Ventricular Function, Left
10.
J Pain Res ; 14: 1193-1200, 2021.
Article in English | MEDLINE | ID: mdl-33976569

ABSTRACT

BACKGROUND: Radiofrequency ablation (RFA) is a denervation therapy commonly performed for pain of facet etiology. Degenerative spondylolisthesis, a malalignment of the spinal vertebrae, may be a co-existing condition contributing to pain; yet the effect of RFA on advancing listhesis is unknown. To the extent that denervating RFA may weaken paraspinal muscles that provide stability to the spine, the therapy can potentially contribute to progressive spinal instability. METHODS: Single-center, prospective, observational pilot study in an interventional pain practice to test the hypothesis that RFA of painful facets in the setting of spondylolisthesis may contribute to advancement of further degenerative spondylolisthesis. Fifteen participants with pre-existing degenerative Grade I or Grade II spondylolisthesis and coexisting axial lumbar pain underwent lumbar RFA encompassing spondylolisthesis level and followed with post-RFA imaging at 12 months and beyond to measure percent change in spondylolisthesis. RESULTS: The primary outcome was the percent advancement of spondylolisthesis per year measured on post-RFA lateral lumbar spine imaging compared with non-intervention inferred baseline advancement of 2% per very limited observational studies. Among the 15 participants enrolled, 14 completed the study (median age 66; 64.3% women; median BMI 33.5; mean follow-up time 23.9 months). The mean advancement of spondylolisthesis per year after RFA was 1.30% (95% CI -0.14 to 2.78%), with 9/14 below 1.25%. CONCLUSION: Among patients with lumbar pain originating from facets in the setting of degenerative spondylolisthesis who underwent lumbar RFA, the observed advancement of spondylolisthesis is clinically similar to the estimated maximum baseline of 2% per year change. The study findings did not find a destabilizing effect of lumbar RFA in advancing spondylolisthesis in this patient population.

11.
Pain Med ; 21(8): 1708-1717, 2020 08 01.
Article in English | MEDLINE | ID: mdl-32632454

ABSTRACT

BACKGROUND: Pain fellowship programs are facing unique challenges during the COVID-19 pandemic. Restrictions from state governments and the Centers for Disease Control and Prevention have resulted in a rapidly changing and evolving learning environment for todays' fellows. Innovative solutions must be sought to guarantee that proper education is maintained and to ensure the well-being of our trainees. METHODS: We assembled a panel of pain program directors who serve as officers/board members of the Association of Pain Program Directors to provide guidance and formulate recommendations to pain fellowship directors nationally. This guidance is based on reviewing current changes to the Accreditation Council for Graduate Medical Education (ACGME) and American Board of Anesthesiology policies and best available evidence and expert opinion on the use of remote educational activities, research endeavors, and trainee wellness. CONCLUSIONS: The country is in the midst of an unprecedented pandemic. The impact on pain management fellowships has been severe and will likely last for months, resulting in extraordinary challenges to the administration of pain fellowship programs and the education of our fellows. Understanding revisions to ACGME policies, using technology to promote remote learning opportunities, and providing trainees with opportunities to alleviate their anxiety and encourage mental health are beneficial strategies to implement. Together, we can implement innovative solutions to help overcome these challenges.


Subject(s)
Coronavirus Infections , Education, Medical, Graduate , Pain Management , Pandemics , Pneumonia, Viral , Betacoronavirus , COVID-19 , Education, Medical, Graduate/methods , Education, Medical, Graduate/organization & administration , Fellowships and Scholarships , Humans , SARS-CoV-2 , United States
12.
Pain Med ; 21(8): 1718-1728, 2020 08 01.
Article in English | MEDLINE | ID: mdl-32379882

ABSTRACT

BACKGROUND: Pain fellowship programs are facing unique challenges during the COVID-19 pandemic. Restrictions by state governments and the Centers for Disease Control and Prevention have resulted in a rapidly changing and evolving learning environment for today's fellows. Innovative solutions must be sought to maintain proper education and ensure the well-being of our trainees. METHODS: We assembled a panel of pain program directors who serve as officers/board members of the Association of Pain Program Directors, offering guidance and recommendations to pain fellowship directors nationwide. Panel members evaluate the best available evidence and expert opinion on use of remote and virtual platforms in clinical care, adaptability to alterations in clinic and referral management, and provide guidance on postgraduate impact. CONCLUSIONS: The country is in the midst of an unprecedented pandemic. The impact on pain management fellowships has been significant and will likely last for months, resulting in extraordinary challenges to the administration of pain fellowship programs and the education of our fellows. Several strategies will help address these challenges, including employing telehealth capabilities to continue clinical experiences and providing trainees with opportunities to continue their professional growth beyond fellowship completion. Together, we can implement innovative solutions to overcome these challenges.


Subject(s)
Coronavirus Infections , Education, Medical, Graduate , Pain Management , Pandemics , Pneumonia, Viral , Betacoronavirus , COVID-19 , Education, Medical, Graduate/methods , Education, Medical, Graduate/organization & administration , Fellowships and Scholarships , Humans , Job Satisfaction , Mentors , SARS-CoV-2 , United States , Workflow
13.
A A Pract ; 13(7): 278-280, 2019 Oct 01.
Article in English | MEDLINE | ID: mdl-31361662

ABSTRACT

A 44-year-old man, American Society of Anesthesiologists physical status class IV, presented for fulguration of anal condyloma and diverting colostomy. The patient's medical history includes World Health Organization (WHO) class I pulmonary hypertension (PH), right heart failure, and bilateral lower extremity paralysis due to Pott's disease. The patient was not a candidate for neuraxial anesthesia due to sacral decubitus ulcers, and alternative options to general anesthesia (GA) were considered to avoid the high risk of right ventricular (RV) failure and ensuing complications. The case was successfully performed under sedation with dexmedetomidine infusion and bilateral rectus sheath blocks for surgical anesthesia.


Subject(s)
Condylomata Acuminata/surgery , Dexmedetomidine/administration & dosage , Acquired Immunodeficiency Syndrome/complications , Adult , Anesthesia, General , Colostomy , Humans , Male , Nerve Block , Treatment Outcome
14.
JMIR Res Protoc ; 8(4): e12125, 2019 Apr 30.
Article in English | MEDLINE | ID: mdl-31038469

ABSTRACT

BACKGROUND: Approximately 12 million Americans are affected with cancer. Of these, 53% experience pain at all stages of cancer. Pain may remain uncontrolled despite high-dose opioid therapy, and opioids have many well-documented harmful side effects. Intranasal ketamine has been shown to be effective in controlling breakthrough noncancer pain in a double-blind randomized control trial (DBRCT) by Carr et al in 2003 as well as to help with depression in a DBRCT by Lapidus et al in 2014. We seek to obtain preliminary data on the safety, feasibility, and utility of this novel technique for the treatment of uncontrolled cancer pain. OBJECTIVE: This study aimed to obtain preliminary data via a clinical trial addressing the safety, feasibility, pharmacokinetics, and pharmacodynamics of intranasal ketamine. These initial findings will be applied to a subsequent trial to determine the effectiveness and associated toxicities of ketamine in a larger sample of cancer patients and to address the compelling need to identify new, successful management therapies for cancer pain. METHODS: This is an institutional review board- and investigational new drug-approved, prospective phase I/II trial to investigate the safety and use of intranasal ketamine in patients with uncontrolled pain related to cancer or cancer treatment. Informed consent will be obtained prior to all study procedures. All patients will be assigned to the same investigational treatment arm. After patient selection via inclusion/exclusion criteria, patients will be seen over 5 visits, with each visit conducted 2-7 days apart. Patients will be administered ketamine on visits 1-4 and monitored for 240 minutes with continuous pulse oximetry and regular blood pressure checks. Blood samples as well as patient-reported outcomes will be collected at set time points at baseline and after drug delivery. Patients will receive 10 mg intranasal ketamine on visit 1, 10 mg intravenous ketamine on visit 2, 30 mg intranasal ketamine on visit 3, and 50 mg intranasal ketamine on visit 4. On visit 5, an addition blood sample will be drawn. RESULTS: As of March 2019, enrollment is in progress, and a total of 7 subjects have completed the study. Enrollment is expected to be completed by April 2019. Final data analysis will commence soon after, and the results are expected to be submitted for publication in 2019. CONCLUSIONS: If intranasal ketamine can be utilized for pain control in cancer patients, it could provide superior analgesia and better quality of life, without the risk of significant respiratory depression and constipation associated with opioid medications. These findings will be an important initial step toward testing the effectiveness of intranasal ketamine as a nonopioid medication for cancer pain and as potential maintenance outpatient therapy. TRIAL REGISTRATION: ClinicalTrials.gov NCT03146806; https://clinicaltrials.gov/ct2/show/NCT03146806. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/12125.

15.
Curr Pain Headache Rep ; 23(3): 23, 2019 Mar 11.
Article in English | MEDLINE | ID: mdl-30854609

ABSTRACT

PURPOSE OF REVIEW: Low back pain encompasses three distinct sources: axial lumbosacral, radicular, and referred pain. Annually, the prevalence of low back pain in the general US adult population is 10-30%, and the lifetime prevalence of US adults is as high as 65-80%. RECENT FINDINGS: Patient history, physical exam, and diagnostic testing are important components to accurate diagnosis and identification of patient pathophysiology. Etiologies of low back pain include myofascial pain, facet joint pain, sacroiliac joint pain, discogenic pain, spinal stenosis, and failed back surgery. In chronic back pain patients, a multidisciplinary, logical approach to treatment is most effective and can include multimodal medical, psychological, physical, and interventional approaches. Low back pain is a difficult condition to effectively treat and continues to affect millions of Americans every year. In the current investigation, we present a comprehensive review of low back pain and discuss associated pathophysiology, diagnosis, and treatment.


Subject(s)
Low Back Pain/diagnosis , Low Back Pain/physiopathology , Low Back Pain/therapy , Humans
16.
Appl Opt ; 50(19): 3093-100, 2011 Jul 01.
Article in English | MEDLINE | ID: mdl-21743507

ABSTRACT

Selection of modes containing different dark regions was studied in resonators with conical reflectors. The possibility of selecting whole subgroups of such modes was shown in circularly symmetric resonators. To handle single-mode selection employing extra intracavity spatial filters, modified integral equations and a numerical method of their analysis are proposed. Usage of the filter symmetry reduces the size of the four-dimensional matrices corresponding to the equation kernels, and they are analyzed by algorithms for two-dimensional matrices with the best convergence. The optimum resonator parameters for effective selection of different dark modes are found.

17.
Opt Express ; 19(9): 8506-13, 2011 Apr 25.
Article in English | MEDLINE | ID: mdl-21643100

ABSTRACT

Nanostructured materials, designed for enhanced light absorption, are receiving increased scientific and technological interest. In this paper we propose a physical criterion for designing the cross-sectional shape of plasmonic nanowires for improved absorption of a given tightly focused illumination. The idea is to design a shape which increases the matching between the nanowire plasmon resonance field and the incident field. As examples, we design nanowire shapes for two illumination cases: a tightly focused plane wave and a tightly focused beam containing a line singularity. We show that properly shaped and positioned silver nanowires that occupy a relatively small portion of the beam-waist area can absorb up to 65% of the total power of the incident beam.


Subject(s)
Lenses , Lighting/instrumentation , Nanotubes/chemistry , Surface Plasmon Resonance/instrumentation , Absorption , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Light , Scattering, Radiation
18.
Appl Opt ; 50(4): 434-40, 2011 Feb 01.
Article in English | MEDLINE | ID: mdl-21283232

ABSTRACT

Advanced science and technology frequently encounters the need to detect particles in the micrometer and nanometer range of a given composition. While the scattering process of light by small particles is well documented, most conventional analytic methods employ wide illumination of large ensembles of particles. With such an approach, no information can be obtained about single particles due to their weak interaction. In this paper, we show that single particles can be classified with respect to their material composition by analyzing the scattering pattern of a focused Gaussian beam.

19.
Appl Opt ; 50(1): 33-42, 2011 Jan 01.
Article in English | MEDLINE | ID: mdl-21221157

ABSTRACT

In recent years, there has been a mounting interest in better methods of measuring nanoscale objects, especially in fields such as nanotechnology, biomedicine, cleantech, and microelectronics. Conventional methods have proved insufficient, due to the classical diffraction limit or slow and complicated measuring procedures. The purpose of this paper is to explore the special characteristics of singular beams with respect to the investigation of subwavelength objects. Singular beams are light beams that contain one or more singularities in their physical parameters, such as phase or polarization. We focus on the three-dimensional interaction between electromagnetic waves and subwavelength objects to extract information about the object from the scattered light patterns.

20.
Opt Lett ; 35(16): 2729-31, 2010 Aug 15.
Article in English | MEDLINE | ID: mdl-20717438

ABSTRACT

We investigate scattering features of tightly focused singular beams by placing a cylindrical nanowire in the vicinity of a line phase singularity. Applying an illumination wavelength corresponding to silver cylinder plasmonic resonance, we compare the scattering response with that of a perfect conductor. The rigorous modeling employs a 2D version of the Richards-Wolf focusing method and the source model technique. It is found that a cylinder with a plasmonic resonance produces a strong scattering response by deflecting the power flow toward the optical singularity region, where otherwise the power approaches zero.

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