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1.
J Am Heart Assoc ; 12(17): e030739, 2023 09 05.
Article in English | MEDLINE | ID: mdl-37609981

ABSTRACT

Background We aimed to explore the predictive value of the carotid plaque score, compared with the Systematic Coronary Risk Evaluation 2 (SCORE2) risk prediction algorithm, on incident ischemic stroke and major adverse cardiovascular events and establish a prognostic cutoff of the carotid plaque score. Methods and Results In the prospective ACE 1950 (Akershus Cardiac Examination 1950 study), carotid plaque score was calculated with ultrasonography at inclusion in 2012 to 2015. The largest plaque diameter in each extracranial segment of the carotid artery on both sides was scored from 0 to 3 points. The sum of points in all segments provided the carotid plaque score. The cohort was followed up by linkage to national registries for incident ischemic stroke and major adverse cardiovascular events (nonfatal ischemic stroke, nonfatal myocardial infarction, and cardiovascular death) throughout 2020. Carotid plaque score was available in 3650 (98.5%) participants, with mean±SD age of 63.9±0.64 years at inclusion. Only 462 (12.7%) participants were free of plaque, and and 970 (26.6%) had a carotid plaque score of >3. Carotid plaque score predicted ischemic stroke (hazard ratio [HR], 1.25 [95% CI, 1.15-1.36]) and major adverse cardiovascular events (HR, 1.21 [95% CI, 1.14-1.27]) after adjustment for SCORE2 and provided strong incremental prognostic information to SCORE2. The best cutoff value of carotid plaque score for ischemic stroke was >3, with positive predictive value of 2.5% and negative predictive value of 99.3%. Conclusions The carotid plaque score is a strong predictor of ischemic stroke and major adverse cardiovascular events, and it provides incremental prognostic information to SCORE2 for risk prediction. A cutoff score of >3 seems to be suitable to discriminate high-risk subjects. Registration Information clinicaltrials.gov. Identifier: NCT01555411.


Subject(s)
Cardiovascular Diseases , Ischemic Stroke , Stroke , Middle Aged , Humans , Cardiovascular Diseases/diagnosis , Cardiovascular Diseases/epidemiology , Prospective Studies , Risk Factors , Stroke/epidemiology , Carotid Artery, Common , Heart Disease Risk Factors , Plaque, Amyloid
2.
Nurs Open ; 10(11): 7431-7436, 2023 11.
Article in English | MEDLINE | ID: mdl-37209412

ABSTRACT

AIM: To assess the feasibility of delirium screening with the screening tool 4AT conducted by stroke unit nurses. DESIGN: Observational. METHODS: Patients with confirmed acute stroke admitted to the stroke unit at Baerum Hospital, Norway, from March to October 2020, were consecutively recruited. Nurses performed delirium screening using the rapid screening tool 4AT within 24 h of admission, at discharge and when delirium was suspected, and filled out a questionnaire assessing their experiences with the delirium screening. A geriatrician validated the delirium diagnosis. RESULTS: In all, 62 patients were included, mean age 73.3 years. 4AT was performed according to protocol in 49 (79.0%) and 39 (62.9%) patients at admission and discharge respectively. Lack of time (40%) was reported as the most common reason for not performing delirium screening. The nurses reported that the felt competent to carry out the 4AT screening, and did not experience it as significant extra workload. Five patients (8%) were diagnosed with delirium. Delirium screening performed by stroke unit nurses seemed feasible and the nurses experienced that 4AT was a useful tool for this purpose.


Subject(s)
Delirium , Stroke , Humans , Aged , Sensitivity and Specificity , Delirium/diagnosis , Quality Improvement , Hospitalization , Stroke/diagnosis
3.
J Hypertens ; 41(1): 132-139, 2023 01 01.
Article in English | MEDLINE | ID: mdl-36453656

ABSTRACT

OBJECTIVES: Hypertension in midlife is a risk factor for cognitive impairment. Still, the ideal midlife blood pressure (BP) remains unknown. We examined associations between different systolic blood pressure (SBP) levels at the age of 40-43 years and change in SBP over a 25-year period with cognitive function at age 62-65 years. METHODS: We included 2424 individuals born in 1950 who had participated both in the Age 40 Program (1990-1993) and the Akershus Cardiac Examination (ACE) 1950 Study (2012-2015). The exposure was SBP at age 40-43 years and the outcome was cognitive function at age 62-65 years, assessed with Montreal Cognitive Assessment, Delayed recall trial from the Consortium to Establish a Registry for Alzheimer's Disease Word List Memory Task, and Trail Making Test part B (TMT B). RESULTS: Participants were 40.1 ±â€Š0.3 years old with mean SPB 128 ±â€Š13 mmHg at the Age 40 Program, and 63.9 ±â€Š0.6 years old with mean SPB 138 ±â€Š18 at the ACE 1950 Study. Adjusted linear regressions showed no associations between SBP and subsequent cognitive function. In logistic regressions, individuals with SBP ≥140 mmHg, compared to individuals with SBP <120 mmHg (odds ratio 2.29, 95% confidence interval 1.28-4.10, P-value 0.005) had increased risk of an abnormal TMT B-score. Change in SBP during the 25-year follow-up was not associated with cognitive function. CONCLUSIONS: SBP ≥140 mmHg at age 40-43 was associated with reduced capacity on TMT B, a domain specific cognitive test sensitive to vascular impairment. No other associations were found between SBP, or change in SBP, and cognitive function.


Subject(s)
Cognitive Dysfunction , Hypertension , Humans , Aged , Adult , Middle Aged , Blood Pressure , Cognition , Mental Status and Dementia Tests , Hypertension/diagnosis , Cognitive Dysfunction/diagnosis
4.
Public Health ; 208: 9-13, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35660281

ABSTRACT

OBJECTIVES: The purpose of this study is to assess the prevalence and determinants of workplace violence and the sociodemographic risk factors associated. STUDY DESIGN: This was a multicenter cross-sectional study. METHODS: The study was performed using self-compiled Italian version of the World Health Organization's questionnaire on workplace violence online by filling in a Google form. The survey was opened from May 2018 to March 2020 and lasted 5-10 min. RESULTS: The sample consists of 3659 healthcare workers, of which 2525 (69%) are females, 1446 (39.5%) are nurses, and 2029 (55.5%) are health workers from northern Italy. The most frequent age group of the sample is 50-54 years (16.7%). A total of 366 (10%) healthcare workers are victims of physical aggression at work in the last 12 months, of which 6.3% with a weapon. The risk of being a victim of physical aggression at work in the last 12 months is significantly associated with the following independent variables: male gender (odds ratio [OR] 1.72, 95% confidence interval [CI]: 1.36-2.17), work in southern Italy (OR 1.59, 95% CI: 1.10-2.28), and being a nurse (OR 2.56, 95% CI: 2.01-3.25). The risk of being a victim of physical aggression at work with a weapon in the last 12 months is significantly associated with work in southern Italy (OR 9.33, 95% CI: 3.83-22.73). A total of 1723 (47.1%) of healthcare workers declare to be a victim of verbal aggression at work in the last 12 months. The risk of being a victim of verbal aggression at work in the last 12 months is significantly associated with the following independent variables: work in northern Italy (adjusted OR [aOR] 1.54, 95% CI: 1.32-1.81), work in southern Italy (aOR 3.68, 95% CI: 2.90-4.68), and be more than 55 years old (aOR 0.73, 95% CI: 0.63-0.85). CONCLUSIONS: The study underlines that the problem of verbal and physical aggression against healthcare workers is still central and is a further starting point for research. The prevalence of violence is difficult to assess because violent incidents are underreported or unreported. The results of the study suggest that increased awareness is needed to develop effective control strategies at the individual, hospital, and national levels to prevent aggression and improve the conditions of victims.


Subject(s)
Workplace Violence , Aggression , Cross-Sectional Studies , Female , Health Personnel , Humans , Italy/epidemiology , Male , Middle Aged , Surveys and Questionnaires , Workplace , Workplace Violence/prevention & control
5.
Eur Geriatr Med ; 13(3): 695-703, 2022 06.
Article in English | MEDLINE | ID: mdl-35267190

ABSTRACT

PURPOSE: Several of those who have been infected with COVID-19 suffer from the post-COVID-19 condition months after the acute infection. Little is known about how older survivors have experienced the consequences and how these have affected their lives. The aim of this study was to explore how older survivors experienced post-COVID-19 condition and life changes approximately 6 months after hospitalisation for COVID-19. METHODS: The study had an explorative and descriptive design. Semi-structured interviews were performed with 17 participants from two local hospitals, 11 men and 6 women, aged 60 years and older (age range 60-96), approximately 6 months after hospitalisation for COVID-19. A thematic descriptive analysis inspired by Braun and Clarke was used. RESULTS: Two main themes and seven subthemes were revealed. The main themes were: From few to various persistent symptoms and Existential thoughts and reflections. Most of the participants experienced various physical and/or cognitive symptoms, such as reduced physical fitness, heavy breathing, fatigue, and 'brain fog'. On the other hand, they also experienced guilt and gratitude for having survived. The recognition of having achieved other life perspectives was also present. CONCLUSION: Six months after undergone COVID-19 the participants still experienced various distressing symptoms, which were in line with larger studies. The novel findings of this study were connected to the existential area, where the patients' thoughts and reflections of guilt, gratitude, and new life perspectives were revealed. These findings are important for health professionals to consider when treating patients after COVID-19.


Subject(s)
COVID-19 , Aged , Aged, 80 and over , Brain , COVID-19/epidemiology , COVID-19/therapy , Female , Guilt , Hospitalization , Humans , Male , Mental Fatigue , Middle Aged , Qualitative Research , Quality of Life , Survivors
6.
Eur Rev Med Pharmacol Sci ; 26(3): 1056-1064, 2022 02.
Article in English | MEDLINE | ID: mdl-35179773

ABSTRACT

OBJECTIVE: SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) has been identified in China as responsible for viral pneumonia, now called COVID-19 (Coronavirus Disease 2019). Patients infected can develop common symptoms like cough and sore throat, and, in severe cases, acute respiratory syndrome and even death. To optimize the available resources, it is necessary to identify in advance the subjects that will develop a more serious illness, therefore requiring intensive care.The neutrophil / lymphocyte ratio (NLR) parameter, resulting from the blood count, could be a significant marker for the diagnosis and management of risk stratification. PATIENTS AND METHODS: A retrospective, single-center case-control observational study was conducted. The differential cell count of leukocytes, the NLR and the clinical course of patients hospitalized in intensive care with COVID-19 were analyzed, comparing them with other patients (COVID-19 and non-COVID-19) and healthy individuals selected among workers of the Teaching Hospital Policlinico Umberto I in Rome. RESULTS: 370 patients (145 cases and 225 controls) were included in the case-control study, 211 males (57%) and 159 females (43%). The average age of the population was 63 years (SD 16.35). In the group of cases, out of 145 patients, 57 deaths and 88 survivors were recorded, with a lethality rate of 39.3%. The group of cases has an NLR of 7.83 (SD = 8.07), a much higher value than the control group where an NLR of 2.58 was recorded (SD = 1.93) (p <0.001). The Neutrophils / Lymphocytes ratio may prove to be a diagnostic factor for COVID-19, an NLR> 3.68 revealed an OR 10.84 (95% CI = 6.47 - 18.13) (p <0.005). CONCLUSIONS: The value of NLR considered together with the age variable allows a risk stratification and allows the development of diagnostic and treatment protocols for patients affected by COVID-19. A high neutrophil to lymphocyte ratio suggests worse survival. Risk stratification and management help alleviate the shortage of medical resources and reduce the mortality of critically ill patients.


Subject(s)
COVID-19/blood , COVID-19/diagnosis , Lymphocytes/metabolism , Lymphocytes/virology , Neutrophils/metabolism , Neutrophils/virology , Aged , Biomarkers/blood , Case-Control Studies , Critical Illness , Female , Humans , Intensive Care Units , Italy , Leukocyte Count , Logistic Models , Male , Middle Aged , Prognosis , ROC Curve , Retrospective Studies , Risk Factors , Severity of Illness Index
7.
Clin Ter ; 172(6): 559-563, 2021 Nov 22.
Article in English | MEDLINE | ID: mdl-34821352

ABSTRACT

AIM: To develop and test the effectiveness of an E-learning program for promoting physical activity (PA) and wellness among nurses. BACKGROUND: Restrictions during the coronavirus (COVID-19) pandemic drastically changed many people's lives. Maintaining a healthy lifestyle is an everyday challenge faced by the general popula-tion. Nurses are one of the health care professionals who are typically well-educated in taking care of patients. There are studies that show that night shifts, extended shifts, and obesity have a correlation with the prevalence of acute low back pain among female nurses. PA is the key factor in the prevention and treatment of many chronic diseases, resulting in an improvement in the quality of life. The impact of social media and technology on our lives is undeniable in the modern era. DESIGN: This study will be a single-centre, single-blind, randomi-zed controlled trial executed on an E-learning platform to provide the control and intervention groups with a distance learning program. Par-ticipants will be randomly assigned to either the control or intervention group. Participants in the control group will only sign up for module 1 of the PA modules, which only comprises information on PA and health promotion. On the other hand, the participants in the intervention group are expected to carry out 3 modules of exercises at home three days a week for a total duration of 8 weeks. The exercises will be performed at moderate intensity (5-6 on the Borg CR10 Scale). ETHICAL ISSUES: This trial will comply with the declaration of Helsinki 1975, as revised in 2000. Informed written consent will be obtained from the participants. The Sapienza University of Rome, institutional ethics committee and review board approval will be requested for this study. CONCLUSION: Establishing an online PA program with good quality, such as a high level of convenience in access and use, simplified, easy to practice, and made available on social media, can minimize the difficulties faced previously in the implementation of an online PA program for nurses, and may enhance the health and wellbeing of many nurses in healthcare institutions.


Subject(s)
COVID-19 , Computer-Assisted Instruction , Nurses , Exercise , Female , Humans , Quality of Life , Randomized Controlled Trials as Topic , SARS-CoV-2 , Single-Blind Method
8.
Antimicrob Resist Infect Control ; 10(1): 87, 2021 06 04.
Article in English | MEDLINE | ID: mdl-34088341

ABSTRACT

BACKGROUND: During the intensive care units' (ICUs) reorganization that was forced by the COVID-19 emergency, attention to traditional infection control measures may have been reduced. Nevertheless, evidence on the effect of the COVID-19 pandemic on healthcare-associated infections (HAIs) is still limited and mixed. In this study, we estimated the pandemic impact on HAI incidence and investigated the HAI type occurring in COVID-19 patients. METHODS: Patients admitted to the main ICU of the Umberto I teaching hospital of Rome from March 1st and April 4th 2020 were compared with patients hospitalized in 2019. We assessed the association of risk factors and time-to-first event through multivariable Fine and Grey's regression models, that consider the competitive risk of death on the development of HAI (Model 1) or device related-HAI (dr-HAI, Model 2) and provide estimates of the sub-distribution hazard ratio (SHR) and its associated confidence interval (CI). A subgroup analysis was performed on the 2020 cohort. RESULTS: Data from 104 patients were retrieved. Overall, 59 HAIs were recorded, 32 of which occurred in the COVID-19 group. Patients admitted in 2020 were found to be positively associated with both HAI and dr-HAI onset (SHR: 2.66, 95% CI 1.31-5.38, and SHR: 10.0, 95% CI 1.84-54.41, respectively). Despite being not confirmed at the multivariable analysis, a greater proportion of dr-HAIs seemed to occur in COVID-19 patients, especially ventilator-associated pneumonia, and catheter-related urinary tract infections. CONCLUSIONS: We observed an increase in the incidence of patients with HAIs, especially dr-HAIs, mainly sustained by COVID-19 patients. A greater susceptibility of these patients to device-related infections was hypothesized, but further studies are needed.


Subject(s)
COVID-19/epidemiology , Cross Infection/epidemiology , Intensive Care Units/statistics & numerical data , Aged , Catheter-Related Infections/epidemiology , Critical Care , Delivery of Health Care , Female , Hospitalization , Hospitals, Teaching , Humans , Incidence , Infection Control , Male , Middle Aged , Pandemics , Pneumonia, Ventilator-Associated/epidemiology , Retrospective Studies , Risk Factors , SARS-CoV-2/isolation & purification
9.
Opt Express ; 28(20): 30150-30163, 2020 Sep 28.
Article in English | MEDLINE | ID: mdl-33114899

ABSTRACT

A pair of combined diffractive optical elements (DOEs) realizes a so-called moiré lens, with an optical power which can be tuned by a mutual rotation of the two DOEs around their central optical axis. Earlier demonstrated moiré lenses still suffered from chromatic aberrations. Here we experimentally investigate a multi-color version of such a lens, realized by a pair of multi-order DOEs. These DOEs have a deeper surface structure which modulates the phase of the transmitted light wave by several multiples of 2π. The corresponding multi-order moiré lenses all have the same focal length at a fixed set of harmonic wavelengths within the white light spectrum. The experiments demonstrate that multi-order moiré lenses have significantly reduced chromatic aberrations. We investigate the performance of the lens for narrow band and white light imaging applications.

10.
J Microsc ; 271(3): 337-344, 2018 09.
Article in English | MEDLINE | ID: mdl-29932461

ABSTRACT

Alvarez lenses are actuated lens-pairs which allow one to tune the optical power by mechanical displacement of subelements. Here, we show that a recently realized modified Alvarez lens design which does not require mechanical actuation can be integrated into a confocal microscope. Instead of mechanically moving them, the sublenses are imaged onto each other in a 4f-configuration, where the lateral image shift leading to a change in optical power is created by a galvo-mirror. The avoidance of mechanical lens shifts leads to a large speed gain for axial (and hence also 3D) image scans compared to classical Alvarez lenses. We demonstrate that the suggested operation principle is compatible with confocal microscopy. In order to optimize the system, we have drawn advantage of the flexibility a liquid-crystal spatial light modulator offers for the implementation. For given specifications, dedicated diffractive optical elements or freeform elements can be used in combination with resonant galvo-scanners or acousto-optic beam deflectors, to achieve even faster z-scans than reported here, reaching video rate.

11.
Acta Paediatr ; 106(5): 698-709, 2017 May.
Article in English | MEDLINE | ID: mdl-28128867

ABSTRACT

Medically assisted fertility treatment, including assisted reproductive technology (ART), is increasingly being used and the subsequent child health outcomes are of interest. Some studies have suggested an elevated risk of somatic morbidity, while others have reported an elevated cancer risk. This review summarises the literature on fertility treatments and childhood cancer, based on 23 cohort and case-control studies. CONCLUSION: The findings varied, but reassuring results on overall childhood cancer and fertility treatment were observed. However, some studies suggested an elevated risk of haematological cancers. More large population-based studies are needed, and the growing population of ART children should be monitored.


Subject(s)
Hematologic Neoplasms/etiology , Reproductive Techniques, Assisted/adverse effects , Central Nervous System Neoplasms/etiology , Humans
12.
Eur J Cardiovasc Nurs ; 15(3): e60-9, 2016 04.
Article in English | MEDLINE | ID: mdl-25888607

ABSTRACT

BACKGROUND: While the overall incidence of acute myocardial infarction in Norway decreased in 2001-2009, this was not observed for younger adults. Smoking cessation, physical activity and healthy diet are associated with reduced risk of recurrent cardiovascular events and mortality among individuals with established coronary heart disease (CHD). AIMS: We investigated whether adults in their 40s with or without CHD had 1) attempted to improve their health behaviour during the previous year, and 2) had confidence in their ability to improve their health behaviour over the next five years. METHODS: Study participants were 22,019 40-49 year olds from the Hordaland Health Study. Associations between improvements and intentions regarding health behaviours and prevalent CHD were assessed with logistic regression analyses. RESULTS: One hundred and seventy-five (0.8%) participants reported to have CHD. After controlling for demographic, lifestyle and psychosocial variables, attempts to improve health behaviour during the prior year were associated with a threefold increased odds of prevalent CHD (odds ratio 3.07; 95% confidence interval, 1.91-4.95). Confidence in improving health behaviour during the subsequent five years was not associated with increased odds of prevalent CHD. CONCLUSIONS: Adults in their 40s with CHD were more likely to have attempted to improve their health behaviour during the past year compared with those without CHD. Healthcare providers should take advantage of these positive attitudes to encourage further positive improvements.


Subject(s)
Coronary Disease/psychology , Health Promotion , Risk Reduction Behavior , Adult , Attitude to Health , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Norway , Odds Ratio , Risk Factors
13.
Opt Express ; 21(14): 16541-51, 2013 Jul 15.
Article in English | MEDLINE | ID: mdl-23938505

ABSTRACT

Spatial Light Modulators (SLMs) can emulate the classic microscopy techniques, including differential interference (DIC) contrast and (spiral) phase contrast. Their programmability entails the benefit of flexibility or the option to multiplex images, for single-shot quantitative imaging or for simultaneous multi-plane imaging (depth-of-field multiplexing). We report the development of a microscope sharing many of the previously demonstrated capabilities, within a holographic implementation of a stereo microscope. Furthermore, we use the SLM to combine stereo microscopy with a refocusing filter and with a darkfield filter. The instrument is built around a custom inverted microscope and equipped with an SLM which gives various imaging modes laterally displaced on the same camera chip. In addition, there is a wide angle camera for visualisation of a larger region of the sample.


Subject(s)
Holography/instrumentation , Image Enhancement/instrumentation , Imaging, Three-Dimensional/instrumentation , Lighting/instrumentation , Microscopy/instrumentation , Equipment Design , Equipment Failure Analysis
14.
Phys Rev Lett ; 111(2): 023601, 2013 Jul 12.
Article in English | MEDLINE | ID: mdl-23889398

ABSTRACT

Blackbody radiation around hot objects induces ac Stark shifts of the energy levels of nearby atoms and molecules. These shifts are roughly proportional to the fourth power of the temperature and induce a force decaying with the third power of the distance from the object. We explicitly calculate the resulting attractive blackbody optical dipole force for ground state hydrogen atoms. Surprisingly, this force can surpass the repulsive radiation pressure and actually pull the atoms against the radiation energy flow towards the surface with a force stronger than gravity. We exemplify the dominance of the "blackbody force" over gravity for hydrogen in a cloud of hot dust particles. This overlooked force appears relevant in various astrophysical scenarios, in particular, since analogous results hold for a wide class of other broadband radiation sources.


Subject(s)
Cosmic Radiation , Models, Theoretical , Optics and Photonics , Hot Temperature , Hydrogen/chemistry , Physics , Thermodynamics
15.
Biomed Opt Express ; 2(10): 2859-70, 2011 Oct 01.
Article in English | MEDLINE | ID: mdl-22025990

ABSTRACT

Combining several methods for contact free micro-manipulation of small particles such as cells or micro-organisms provides the advantages of each method in a single setup. Optical tweezers, which employ focused laser beams, offer very precise and selective handling of single particles. On the other hand, acoustic trapping with wavelengths of about 1 mm allows the simultaneous trapping of many, comparatively large particles. With conventional approaches it is difficult to fully employ the strengths of each method due to the different experimental requirements. Here we present the combined optical and acoustic trapping of motile micro-organisms in a microfluidic environment, utilizing optical macro-tweezers, which offer a large field of view and working distance of several millimeters and therefore match the typical range of acoustic trapping. We characterize the acoustic trapping forces with the help of optically trapped particles and present several applications of the combined optical and acoustic trapping, such as manipulation of large (75 µm) particles and active particle sorting.

16.
Phys Rev Lett ; 103(8): 083602, 2009 Aug 21.
Article in English | MEDLINE | ID: mdl-19792729

ABSTRACT

We demonstrate the contrast enhancement of images within a ghost-imaging system by use of nonlocal phase filters. We use parametric down-conversion as the two-photon light source and two separated phase modulators, in the signal and idler arms which represent different phase filters and objects, respectively. We obtain edge enhanced images as a direct consequence of the quantum correlations in the orbital angular momentum (OAM) of the down-converted photon pairs. For phase objects, with differently orientated edges, we show a violation of a Bell-type inequality for an OAM subspace, thereby unambiguously revealing the quantum nature of our ghost-imaging arrangement.

17.
Opt Express ; 17(10): 8287-93, 2009 May 11.
Article in English | MEDLINE | ID: mdl-19434161

ABSTRACT

We observe entanglement between photons in controlled super-position states of orbital angular momentum (OAM). By drawing a direct analogy between OAM and polarization states of light, we demonstrate the entangled nature of high order OAM states generated by spontaneous downconversion through violation of a suitable Clauser Horne Shimony Holt (CHSH)-Bell inequality. We demonstrate this violation in a number of two-dimensional subspaces of the higher dimensional OAM Hilbert space.

18.
J Microsc ; 230(Pt 1): 134-42, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18387048

ABSTRACT

We present the implementation of a spiral phase plate in a standard bright-field microscope to enhance the contrast of phase and amplitude samples. The method can be employed in all types of microscopy where standard phase contrast methods are applicable, for example, in bright-field transmission or reflection microscopy using an illumination source with partial spatial coherence. The spiral phase filter is placed into an accessible Fourier plane of the imaging path of the microscope. It is shown that this produces not only a strong contrast enhancement but in theory also improves the spatial resolution of the microscope for white light. A series of different set-ups for transmissive or reflective samples, including epi-illumination, are presented to demonstrate the practical range of applications of this contrasting method. A minute shift of the spiral phase plate out of the centre results in relief-like images that are similar to those obtained by differential interference contrast microscopy. A series of such relief-like images can be numerically processed to obtain quantitative phase and amplitude information of the sample.

19.
Opt Express ; 15(9): 5801-8, 2007 Apr 30.
Article in English | MEDLINE | ID: mdl-19532838

ABSTRACT

We present a fast and flexible non-interferometric method for the correction of small surface deviations on spatial light modulators, based on the Gerchberg-Saxton algorithm. The surface distortion information is extracted from the shape of a single optical vortex, which is created by the light modulator. The method can be implemented in optical tweezers systems for an optimization of trapping fields, or in an imaging system for an optimization of the point-spread-function of the entire image path.

20.
Opt Lett ; 31(19): 2824-6, 2006 Oct 01.
Article in English | MEDLINE | ID: mdl-16969390

ABSTRACT

We report the observation of particles trapped at an air-water surface orbiting in a reverse direction with respect to the orbital angular momentum of the light field. The effect is explained by a combination of asymmetric particle shape and confinement of the particle on the 2D air-water interface. The experiment highlights the strong influence of the particle shape on the momentum transfer, an effect that is often not considered in optical trapping experiments.

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