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Kumar MT, Kar N, Namboodiri V, Joy A, Sreeenivasan D, Kumar S, Bortel TV. Post-traumatic stress and depression following a landslide linked to the 2018 floods in Kerala, India: Relevance of screening. J Emerg Manag 2023; 21:85-96. [PMID: 36779924 DOI: 10.5055/jem.0728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
There is scant information on early manifestation of trauma due to catastrophic natural events and its relation with stress-related disorders. The specific objective of this study was to estimate and compare the prevalence of post-traumatic stress and depression on day 3 (D3) and week 6 (W6) following the 2018 flood in Kerala, India. In a cross-sectional study, symptoms of post-traumatic stress and depression were studied at D3 using primary care Post-Traumatic Stress Disorder screen for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) (PC-PTSD-5), and then at W6 using PC-PTSD-5, Screening Questionnaire for Disaster Mental Health, PTSD Checklist for DSM-5 (PCL-5), and Becks Depression Inventory. Majority (70 percent) were screen positive at D3 (n = 20) compared with 30 percent at W6 (n = 50), with a decreased frequency of all symptoms. Being PC-PTSD-5 screen positive at W6 was significantly associated with the presence of threat to life, physical injury, and death of relatives or neighbors. According to PCL-5, at W6, 46 percent had possible PTSD. Except damage to property, other disaster related or sociodemographic variables were not associated with the risk of having PTSD. Positive predictive value of PC-PTSD-5 (D3) for PTSD (PCL-5) at W6 was 64.3 percent. Depression and possibility of PTSD were significantly associated. A considerable proportion of victims continued to have post-traumatic stress and depression although the -frequency decreased over time. A simple screening measure may help to identify victims with possible PTSD.
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Affiliation(s)
- Manoj Therayil Kumar
- FRCPsych, Hon Consultant Psychiatrist, MPFT, Stafford, Hon Senior Lecturer, Keele University, Keele, Newcastle ST5 5BG, United Kingdom; Director, Institute for Mind and Brain, Thrissur, Kerala, India
| | - Nilamadhab Kar
- Consultant Psychiatrist and College Tutor, Black Country Partnership NHS Foundation Trust, Honorary Professor, University of Wolverhampton, Wolverhampton, United Kingdom; Honorary Professor, Sri Sri University, Cuttack, Odisha, India. ORCID: https://orcid.org/0000-0002-8801-9245
| | | | - Aloka Joy
- Consultant Psychiatrist, Institute for Mind and Brain, Thrissur, Kerala, India
| | - Dhanya Sreeenivasan
- Clinical Psychologist, Institute for Mind and Brain, Thrissur, Kerala, India
| | - Sebind Kumar
- Department of Psychiatry, Government Medical College, Thrissur, Kerala, India
| | - Tine Van Bortel
- Professor of Global Health & Wellbeing, Faculty of Health and Life Sciences, De Montfort University, Leicester, United Kingdom; Principle Investigator in Public Mental Health & Wellbeing, Cambridge Public Health, University of Cambridge, Cambridge, United Kingdom
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Vane L, Alvarez F, Namboodiri V, Abar M. Ethanol dehydration performance of three types of commercial-grade zeolite permselective membranes. J Chem Technol Biotechnol 2022; 97:1966-1977. [PMID: 37941567 PMCID: PMC10631551 DOI: 10.1002/jctb.7141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 05/21/2022] [Indexed: 11/10/2023]
Abstract
BACKGROUND Many organic solvents form difficult-to-separate mixtures with water and have an affinity for water, making drying a potential reuse prerequisite. Pervaporation (PV) and vapor permeation (VP) membrane technologies hold promise for energy-efficient solvent drying. Several water-selective membrane materials are commercially available, but performance data is limited, particularly for two recently commercialized membrane materials: chabazite (CHA) and T-type zeolites. In this work, commercial-grade samples of CHA and T-type membranes, along with a NaA zeolite membrane, were evaluated for the removal of water from ethanol. RESULTS The CHA sample had the highest initial PV water permeance (6820 GPU) and water permselectivity (3430) with 5 wt% water in ethanol at 50 °C. Initial NaA membrane performance was slightly lower (6060 GPU and 3260), while the T-type membrane had the lowest initial permeance and selectivity (4260 GPU and 1090). Performance declined over time, most notably for the NaA membrane, for which water permeance fell over 50% through 39 days of testing. The T-type membrane exhibited the steadiest PV water permeance, but the most variable ethanol permeance. CONCLUSION The PV performance of the three membranes largely overlapped the predicted range for T-type membranes. That performance generally exceeds the anticipated ethanol drying performance of non-zeolitic PV membranes but is less than that predicted for NaA and CHA membranes. The present CHA membrane results, along with other recent reports, refine earlier predictions of the ethanol dehydration performance of that type of zeolite. The changing performance with time should be understood to properly design a solvent dehydration system.
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Affiliation(s)
- Leland Vane
- United States Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Cincinnati, OH, USA
| | - Franklin Alvarez
- United States Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Cincinnati, OH, USA
| | - Vasudevan Namboodiri
- United States Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Cincinnati, OH, USA
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Namboodiri V, George S, Singh SP. The Mental Healthcare Act 2017 of India: A challenge and an opportunity. Asian J Psychiatr 2019; 44:25-28. [PMID: 31302439 DOI: 10.1016/j.ajp.2019.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 07/06/2019] [Accepted: 07/07/2019] [Indexed: 02/06/2023]
Abstract
The Mental Healthcare Act 2017 replaced the Mental Health Act 1987, subsequent to India's ratification of the United Nations Convention on the Rights of Persons with Disabilities in 2007. The Mental Healthcare Act (MHCA) 2017 upholds patient autonomy, dignity, rights and choices during mental healthcare and thus marks a bold step in India's mental health legislation. This new Law marks a major shift in the way mental healthcare is delivered, as it aims to protect and promote the rights of people during the delivery of mental healthcare. Within this Act, a capacitous individual cannot be coerced into receiving treatment for mental illness and inpatient admissions can be 'independent' or 'supported'. 'Supported admission' replaces involuntary admission from the previous legislation. State mental health authorities and mental health review boards will play a major role in the implementation of the new Act. The Mental Healthcare Act 2017 is aimed at bringing about radical transformation to mental healthcare in India.
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Affiliation(s)
| | - Sanju George
- Rajagiri School of behavioural sciences and research, Rajagiri College of Social Sciences (Autonomous), Rajagiri P. O., Kalamassery, Kochi, Kerala, 683104 India.
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Abstract
CONTEXT Existing literature suggests an alarming rate of depression in cancer caregivers, which is comparable to or even higher than in patients themselves. There are no studies on depression among caregivers of breast cancer from India. AIMS The aim is to study the prevalence and determinants of depression in caregivers of breast cancer. SETTINGS AND DESIGN This is a cross-sectional study of 384 patient-caregiver dyads at a cancer research center in South India. MATERIALS AND METHODS Based on the International Classification of Diseases, 10th Revision Diagnostic Criteria for Research depression was diagnosed, and the severity of depression was assessed using the Hamilton rating scale for depression. A semi-structured pro forma was used to collect the clinical data under patient, caregivers, and care characteristics. RESULTS The prevalence of depression in caregivers was 52.5%. Among them, 35% had mild depression, 16% had moderate depression, and 2% had severe depression. Spousal caregivers, those who resided with the patient, those providing financial support and those with noncaring domestic responsibilities appeared as vulnerable determinants in univariate analysis. However, multivariate analysis did not support the same. CONCLUSION Depression is common among caregivers of patients with breast cancer. There is a need for focused interventions for this group, which may improve the outcome of the patient as well.
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Affiliation(s)
- Sreeja Sahadevan
- Department of Psychiatry, MOSC Medical College, Kolenchery, Ernakulam, Kerala, India
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Abstract
Mental Healthcare Act (MHCA), 2017 aims to protect and promote the rights of patients during mental health care. This Act promotes patient's autonomy and choice for those with ability to make decisions on mental health care, independent of the level of risks or complexities. Supported decision-making can vary from minimal or no support to complete support for decision-making. A decision by a nominated representative is restricted to those with incapacity for mental healthcare decisions. Capacity assessment for mental healthcare is a specific task in the clinical application of the act. This article is meant to guide clinicians on capacity assessment during the implementation of MHCA.
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Silva RG, Szabo J, Namboodiri V, Krishnan ER, Rodriguez J, Zeigler A. Evaluation of an environmentally sustainable UV-assisted water treatment system for the removal of Bacillus globigii spores in water. Water Sci Technol Water Supply 2018; 18:968-975. [PMID: 30505259 PMCID: PMC6260950 DOI: 10.2166/ws.2017.165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Development of greener water treatment technologies is important for the production of safe drinking water and water security applications, such as decontamination. Chlorine assisted disinfection is common and economical, but can generate disinfection byproducts (DBPs) that may be of health concern. DBPs are formed due to the reaction of chlorine with naturally occurring organic and inorganic substances in water. Currently, various innovative technologies are being developed as alternative approaches for preventing DBPs during water treatment. In this study, we evaluated the effectiveness of a novel combination of high efficiency flow filtration and UV disinfection treatment system for the removal of Bacillus globigii (B. globigii) spores in water. The filtration system consists of a charged membrane filter (CMF) that not only helps to remove suspended particles but also reduces the impact of other impurities including bio organisms. In order to get most performance details, the CMF was evaluated at clean, half-life, and end of life (EOL) conditions along with 100% UV transmittance (UVT). In addition, the effectiveness of the UV system was evaluated as a stand alone system at 100% and 70% EOL intensity. The study was conducted at the US EPA's Test and Evaluation (T&E) Facility in Cincinnati, OH, using B. globigii, a surrogate for B. anthracis spores. This non-chemical environmentally-friendly CMF/UV combination system and the stand alone UV unit showed greater than 6.0 log removal of B. globigii during the tests.
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Affiliation(s)
- R G Silva
- APTIM, Test and Evaluation Facility, 1600 Gest Street, Cincinnati, OH 45204, USA
| | - J Szabo
- US EPA, National Homeland Security Research Center, Cincinnati, OH, USA
| | - V Namboodiri
- US EPA, National Risk Management Research Laboratory, Cincinnati, OH, USA
| | - E R Krishnan
- APTIM, Test and Evaluation Facility, 1600 Gest Street, Cincinnati, OH 45204, USA
| | - J Rodriguez
- Aqua Treatment Service, Mechanicsburg, PA, USA
| | - A Zeigler
- Waterline Technology, Mansfield, OH, USA
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Mondal JA, Namboodiri V, Mathi P, Singh AK. Alkyl Chain Length Dependent Structural and Orientational Transformations of Water at Alcohol-Water Interfaces and Its Relevance to Atmospheric Aerosols. J Phys Chem Lett 2017; 8:1637-1644. [PMID: 28333468 DOI: 10.1021/acs.jpclett.7b00324] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Although the hydrophobic size of an amphiphile plays a key role in various chemical, biological, and atmospheric processes, its effect at macroscopic aqueous interfaces (e.g., air-water, oil-water, cell membrane-water, etc.), which are ubiquitous in nature, is not well understood. Here we report the hydrophobic alkyl chain length dependent structural and orientational transformations of water at alcohol (CnH2n+1OH, n = 1-12)-water interfaces using interface-selective heterodyne-detected vibrational sum frequency generation (HD-VSFG) and Raman multivariate curve resolution (Raman-MCR) spectroscopic techniques. The HD-VSFG results reveal that short-chain alcohols (CnH2n+1OH, n < 4, i.e., up to 1-propanol) do not affect the structure (H-bonding) and orientation of water at the air-water interface; the OH stretch band maximum appears at ∼3470 cm-1, and the water H atoms are pointed toward the bulk water, that is, "H-down" oriented. In contrast, long-chain alcohols (CnH2n+1OH, n > 4, i.e., beyond 1-butanol) make the interfacial water more strongly H-bonded and reversely orientated; the OH stretch band maximum appears at ∼3200 cm-1, and the H atoms are pointed away from the bulk water, that is, "H-up" oriented. Interestingly, for the alcohol of intermediate chain length (CnH2n+1OH, n = 4, i.e, 1-butanol), the interface is quite unstable even after hours of its formation and the time-averaged result is qualitatively similar to that of the long-chain alcohols, indicating a structural/orientational crossover of interfacial water at the 1-butanol-water interface. pH-dependent HD-VSFG measurements (with H2O as well as isotopically diluted water, HOD) suggest that the structural/orientational transformation of water at the long-chain alcohol-water interface is associated with the adsorption of OH- anion at the interface. Vibrational mapping of the water structure in the hydration shell of OH- anion (obtained by Raman-MCR spectroscopy of NaOH in HOD) clearly shows that the water becomes strongly H-bonded (OH stretch max. ≈ 3200 cm-1) while hydrating the OH- anion. Altogether, it is conceivable that alcohols of different hydrophobic chain lengths that are present in the troposphere will differently affect the interfacial electrostatics and associated chemical processes of aerosol droplets, which are critical for cloud formation, global radiation budget, and climate change.
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Affiliation(s)
- Jahur A Mondal
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, HBNI , Trombay, Mumbai 400085, India
| | - V Namboodiri
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, HBNI , Trombay, Mumbai 400085, India
| | - P Mathi
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, HBNI , Trombay, Mumbai 400085, India
| | - Ajay K Singh
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, HBNI , Trombay, Mumbai 400085, India
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Ahmed M, Namboodiri V, Singh AK, Mondal JA. On the intermolecular vibrational coupling, hydrogen bonding, and librational freedom of water in the hydration shell of mono- and bivalent anions. J Chem Phys 2014; 141:164708. [DOI: 10.1063/1.4899070] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ahmed M, Namboodiri V, Singh AK, Mondal JA, Sarkar SK. How Ions Affect the Structure of Water: A Combined Raman Spectroscopy and Multivariate Curve Resolution Study. J Phys Chem B 2013; 117:16479-85. [DOI: 10.1021/jp4100697] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Mohammed Ahmed
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - V. Namboodiri
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - Ajay K. Singh
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - Jahur A. Mondal
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - Sisir K. Sarkar
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
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Subramanian B, Christou SY, Efstathiou AM, Namboodiri V, Dionysiou DD. Regeneration of three-way automobile catalysts using biodegradable metal chelating agent--S, S-ethylenediamine disuccinic acid (S, S-EDDS). J Hazard Mater 2011; 186:999-1006. [PMID: 21177030 DOI: 10.1016/j.jhazmat.2010.11.089] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 11/20/2010] [Accepted: 11/23/2010] [Indexed: 05/30/2023]
Abstract
Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various contaminants such as P, Zn, Pb, Cu and S from commercial aged three-way catalysts, and improving their catalytic performance towards CO and NO pollutants removal has been investigated. Four samples of catalysts from the front and rear inlets of two different TWCs with different mileages and aged under completely different driving conditions were investigated. The catalysts were characterized using various techniques, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurements (N(2) adsorption at 77 K). Quantitative ICP-MS analyses and SEM-EDS studies show the removal of Zn, P and Pb. SEM-EDS images obtained at low magnification (50 μm) showed considerable differences in the surface morphology and composition after washing with S, S-EDDS. However, XRD studies indicated neither little to no removal of major contaminant compound phases nor major structural changes due to washing. Correspondingly, little or no enhancement in BET surface area was observed between the used and washed samples. Light-off curves show that the regeneration procedure employed can effectively improve the catalytic performance towards NO pollutant.
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Affiliation(s)
- B Subramanian
- Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221-0071, USA
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Namboodiri V, Namboodiri M, Flachenecker G, Materny A. Two-photon resonances in femtosecond time-resolved four-wave mixing spectroscopy: β-carotene. J Chem Phys 2010; 133:054503. [DOI: 10.1063/1.3466750] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Subramanian B, Namboodiri V, Khodadoust AP, Dionysiou DD. Extraction of pentachlorophenol from soils using environmentally benign lactic acid solutions. J Hazard Mater 2010; 174:263-269. [PMID: 19800731 DOI: 10.1016/j.jhazmat.2009.09.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2009] [Revised: 07/30/2009] [Accepted: 09/10/2009] [Indexed: 05/28/2023]
Abstract
Soil contamination with pentachlorophenol (PCP) is widespread across the globe. Soil washing/extraction is a common technique to remove this compound. Several soil washing/extraction solutions have been used but a majority of them have the problem of persistence in the environment due to their low biodegradability. Our aim was to investigate mixed solutions of lactic acid and water as potential alternatives to surfactant solutions or organic solvent systems used for the removal of PCP from three soils: montmorillonite, a natural sediment (with organic matter), and the same sediment without organic matter (ignited sediment). This study included the optimization of the concentration of lactic acid in water for maximum extraction efficiency and the determination of linear desorption constants for removal of PCP from the three soils with lactic acid. The effect of soil/sediment organic matter on the extraction efficiency was also studied. Initial experiments showed that 24h was the optimum extraction time. High extraction efficiencies were obtained for montmorillonite (40-80%) and ignited sediment ( approximately 90%). The natural sediment exhibited low PCP extraction due to presence of organic matter, while high desorption coefficient values ( approximately 23 L/kg) were obtained for the ignited sediment. For all soils, a decrease in extraction was observed at higher concentrations of lactic acid. The specific surface area of soil/sediment was also found to be an important factor affecting the extraction of PCP.
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Affiliation(s)
- Bhargavi Subramanian
- Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221-0071, USA
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Abstract
Heroin misuse in pregnancy is a significant health and social problem, and it can have an adverse effect on the mother and the baby. Although heroin and methadone have no specific teratogenic potential, 48-94% of children exposed in utero will have neonatal abstinence syndrome (NAS). The primary aim of this case report is to raise awareness of NAS among clinicians and to remind them that although very common, it is not inevitable. The risk of NAS can be further minimised by offering comprehensive and co-ordinated antenatal care that addresses the various biopsychosocial needs of the pregnant woman. Further, a brief description of NAS and a review of evidence in the field of management of opioid misuse in pregnancy, as relevant to this case, are provided. We have also included the patient's own reflections on her pregnancy and treatment.
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Affiliation(s)
- Vasudevan Namboodiri
- Birmingham and Solihull Mental Health NHS Trust, Addiction Psychiatry, The Bridge, 15 Larch Croft, Birmingham B37 7UR, UK
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Abstract
A significant proportion of patients who are heroin-dependant and receiving treatment in the community serve prison sentences at some point in their lives, meaning their treatment continues "on the inside". Although prison inmates are promised the same quality of care as they would get "on the outside", this is not always the case. Some drawbacks of the drug treatments offered in prisons can lead to people smuggling drugs into prisons. The present work describes how a patient, who is heroin dependant and attending a community drug and alcohol team for methadone maintenance treatment, smuggled methadone and heroin into prison, his reasons for doing that, his personal description of the extent of drug use in prisons and finally what can be done to stop it from treatment and policy perspectives. Drug misuse is common in prisons. Much more can be done at treatment and policy levels to prevent people smuggling drugs into prison.
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Affiliation(s)
- Sanju George
- Birmingham and Solihull Mental Health NHS Trust, Addiction Psychiatry, The Bridge Substance Misuse Service, 15 Larch Croft, Birmingham, B37 7UR, UK
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Scaria A, Namboodiri V, Konradi J, Materny A. Ultrafast vibrational dynamics observed in higher electronic excited states of iodine using pump-UV DFWM spectroscopy. Phys Chem Chem Phys 2008; 10:983-9. [PMID: 18259637 DOI: 10.1039/b715814a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
By using a combination of an initial pump pulse and a degenerate four-wave mixing process, we show that an interrogation of the vibrational dynamics occurring in different electronic states of molecules is possible. The technique is applied to iodine. The initial pump pulse is used to populate the B((3)Pi) state of molecular iodine in the gas phase. Now, by using an internal time delay in the DFWM process, which is resonant with the transition between the B state and a higher lying ion-pair state, the vibrational dynamics of the B state and the ion-pair state could be observed. States of even symmetry are investigated, which are accessed by a one photon transition from the B state. By a proper choice of the wavelengths used for the pump and DFWM beams, the dynamics of ion-pair states belonging to two different tiers are monitored.
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Affiliation(s)
- A Scaria
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759, Bremen, Germany
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Konradi J, Gaal A, Scaria A, Namboodiri V, Materny A. Influence of electronic resonances on mode selective excitation with tailored laser pulses. J Phys Chem A 2008; 112:1380-91. [PMID: 18225867 DOI: 10.1021/jp0745079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, the gain of the temporal resolution entails a poor spectral resolution due to the inherent spectral width of the femtosecond excitation pulses. Modifications of the phase shape of one of the exciting pulses results in dramatic changes of the mode distribution reflected in coherent anti-Stokes Raman spectra. A feedback-controlled optimization of specific modes making use of phase and/or amplitude modulation of the pump laser pulse is applied to selectively influence the anti-Stokes signal spectrum. The optimization experiments are performed under electronically nonresonant and resonant conditions. The results are compared and the role of electronic resonances is analyzed. It can be clearly demonstrated that these resonances are of importance for a selective excitation by means of phase and amplitude modulation. The mode selective excitation under nonresonant conditions is determined mainly by the variation of the spectral phase of the laser pulse. Here, the modulation of the spectral amplitudes only has little influence on the mode ratios. In contrast to this, the phase as well as amplitude modulation contributes considerably to the control process under resonant conditions. A careful analysis of the experimental results reveals information about the mechanisms of the mode control, which partially involve molecular dynamics in the electronic states.
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Affiliation(s)
- J Konradi
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany
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Abstract
Femtosecond degenerate four-wave-mixing spectroscopy following an initial pump laser pulse was used to observe the wave packet dynamics in excited electronic states of gas phase iodine. The focus of the investigation was on the ion pair states belonging to the first tier dissociating into the two ions I-(1S) + I+(3P2). By a proper choice of the wavelengths of the initial pump and degenerate four-wave-mixing pulses, we were able to observe the vibrational dynamics of the B (3)Pi(u) (+) state of molecular iodine as well as the ion pair states accessible from there by a one-photon transition. The method proves to be a valuable tool for exploring higher lying states that cannot be directly accessed from the ground state due to selection rule exclusion or unfavorable Franck-Condon overlap.
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Affiliation(s)
- A Scaria
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany
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Scaria A, Konradi J, Namboodiri V, Sackmann M, Materny A. Femtosecond CARS on molecules exhibiting ring puckering vibration in gas and liquid phase. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.11.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Kabalka GW, Wang L, Pagni RM, Hair CM, Namboodiri V. Solventless Suzuki Coupling Reactions On Palladium-Doped Potassium Fluoride Alumina. SYNTHESIS-STUTTGART 2003. [DOI: 10.1055/s-2003-36821] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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