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Item 9 of the Patient Health Questionnaire-9 (PHQ-9) queries about thoughts of death and self-harm, but not suicidality. Although it is sometimes used to assess suicide risk, most positive responses are not associated with suicidality. The PHQ-8, which omits Item 9, is thus increasingly used in research. We assessed equivalency of total score correlations and the diagnostic accuracy to detect major depression of the PHQ-8 and PHQ-9.
We conducted an individual patient data meta-analysis. We fit bivariate random-effects models to assess diagnostic accuracy.
16 742 participants (2097 major depression cases) from 54 studies were included. The correlation between PHQ-8 and PHQ-9 scores was 0.996 (95% confidence interval 0.996 to 0.996). The standard cutoff score of 10 for the PHQ-9 maximized sensitivity + specificity for the PHQ-8 among studies that used a semi-structured diagnostic interview reference standard (N = 27). At cutoff 10, the PHQ-8 was less sensitive by 0.02 (−0.06 to 0.00) and more specific by 0.01 (0.00 to 0.01) among those studies (N = 27), with similar results for studies that used other types of interviews (N = 27). For all 54 primary studies combined, across all cutoffs, the PHQ-8 was less sensitive than the PHQ-9 by 0.00 to 0.05 (0.03 at cutoff 10), and specificity was within 0.01 for all cutoffs (0.00 to 0.01).
PHQ-8 and PHQ-9 total scores were similar. Sensitivity may be minimally reduced with the PHQ-8, but specificity is similar.
Different diagnostic interviews are used as reference standards for major depression classification in research. Semi-structured interviews involve clinical judgement, whereas fully structured interviews are completely scripted. The Mini International Neuropsychiatric Interview (MINI), a brief fully structured interview, is also sometimes used. It is not known whether interview method is associated with probability of major depression classification.
To evaluate the association between interview method and odds of major depression classification, controlling for depressive symptom scores and participant characteristics.
Data collected for an individual participant data meta-analysis of Patient Health Questionnaire-9 (PHQ-9) diagnostic accuracy were analysed and binomial generalised linear mixed models were fit.
A total of 17 158 participants (2287 with major depression) from 57 primary studies were analysed. Among fully structured interviews, odds of major depression were higher for the MINI compared with the Composite International Diagnostic Interview (CIDI) (odds ratio (OR) = 2.10; 95% CI = 1.15–3.87). Compared with semi-structured interviews, fully structured interviews (MINI excluded) were non-significantly more likely to classify participants with low-level depressive symptoms (PHQ-9 scores ≤6) as having major depression (OR = 3.13; 95% CI = 0.98–10.00), similarly likely for moderate-level symptoms (PHQ-9 scores 7–15) (OR = 0.96; 95% CI = 0.56–1.66) and significantly less likely for high-level symptoms (PHQ-9 scores ≥16) (OR = 0.50; 95% CI = 0.26–0.97).
The MINI may identify more people as depressed than the CIDI, and semi-structured and fully structured interviews may not be interchangeable methods, but these results should be replicated.
Declaration of interest
Drs Jetté and Patten declare that they received a grant, outside the submitted work, from the Hotchkiss Brain Institute, which was jointly funded by the Institute and Pfizer. Pfizer was the original sponsor of the development of the PHQ-9, which is now in the public domain. Dr Chan is a steering committee member or consultant of Astra Zeneca, Bayer, Lilly, MSD and Pfizer. She has received sponsorships and honorarium for giving lectures and providing consultancy and her affiliated institution has received research grants from these companies. Dr Hegerl declares that within the past 3 years, he was an advisory board member for Lundbeck, Servier and Otsuka Pharma; a consultant for Bayer Pharma; and a speaker for Medice Arzneimittel, Novartis, and Roche Pharma, all outside the submitted work. Dr Inagaki declares that he has received grants from Novartis Pharma, lecture fees from Pfizer, Mochida, Shionogi, Sumitomo Dainippon Pharma, Daiichi-Sankyo, Meiji Seika and Takeda, and royalties from Nippon Hyoron Sha, Nanzando, Seiwa Shoten, Igaku-shoin and Technomics, all outside of the submitted work. Dr Yamada reports personal fees from Meiji Seika Pharma Co., Ltd., MSD K.K., Asahi Kasei Pharma Corporation, Seishin Shobo, Seiwa Shoten Co., Ltd., Igaku-shoin Ltd., Chugai Igakusha and Sentan Igakusha, all outside the submitted work. All other authors declare no competing interests. No funder had any role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript; and decision to submit the manuscript for publication.
The ~492 Ma Shetland Ophiolite Complex contains an extensive mantle section, within which numerous podiform chromitite bodies formed during melt percolation in a supra-subduction zone setting. One of the Shetland ophiolite chromitite localities has an unusual style of platinum-group element (PGE) mineralization. Specifically, the Cliff chromitite suite has relatively high (>250 ppm) Pt plus Pd, compared to other chromitites in the Shetland Ophiolite Complex. In this study, we apply petrographic observation, mineral chemistry and novel X-ray microtomography data to elucidate the petrogenesis of PGE-bearing phases at Cliff. The combined datasets reveal that the PGE at Cliff have probably been fractionated by an As-rich fluid, concentrating Pt and Ir into visible (0.1–1 µm) platinum-group minerals (PGM) such as sperrylite and irarsite, respectively. The high (>1 ppm) bulk-rock concentrations of the other PGE (e.g. Os) in the Cliff chromitites suggests the presence of abundant fine-grained unidentified PGM in the serpentinized groundmass. The spatial association of arsenide phases and PGM with alteration rims on Cr-spinel grains suggests that the high Pt and Pd abundances at Cliff result from a late-stage low-temperature (e.g. 200–300°C) hydrothermal event. This conclusion highlights the potential effects that secondary alteration processes can have on modifying and upgrading the tenor of PGE deposits.
Secondary carbonate deposits (similar to speleothems) in urban undergrounds, have been recently highlighted as powerful archives for reconstruction of the historical anthropogenic imprint on the environment. The precise chronology of these secondary carbonate deposits is a key issue for the accurate time reconstruction of environmental conditions. We present three 14C data sets for urban speleothem-like deposits that developed in contrasted man made environments. The first one was sampled in an underground technical gallery of the Palace of Versailles (France), and the other two in a manhole (Saint-Martin spring) of a historical underground aqueduct in Paris (France). The comparison of these records with the bomb peak and relative chronology (laminae counting) allowed us to identify: i) fast carbon transfer from the atmosphere to the urban underground; ii) a high proportion of dead carbon and a high damping effect in relation to possible old carbon stored within urban soils and/or the influence of local fossil carbon burning. This study also shows that the lamination of these deposits is bi-annual in these highly urbanized sites.
Artificial Neural Network based Nonlinear Autoregressive Model is designed to reconstruct and predict Forbush Decrease (FD) Data obtained from Izmiran, Russia. Result indicates that the model seems adequate for short term prediction of the FD data.
The daily time series Flare Index (FI) data of Northern Hemisphere, Southern Hemisphere and Total Disk for Solar Cycle 21- 23 and 24 up to Dec. 2014 has been pre-processed using a 2nd order exponential smoothing algorithm to remove orthogonal noise. The smoothed data in each case is processed for scaling analysis using Rescaled-Range Analysis as well as Finite Variance Scaling Method in order to search for the Hurst exponent. As the value of H obtained from our analysis lies in between 0 and 1, so it can be said that the signal may behave like Fractional Brownian Motion. Also, it is observed that H is less than 0.5 which indicates the data is anti-persistent in nature and it has a strong negative correlation within the signal. The value of H also indicates the oscillating features of the signal which might have some fundamental periodicities in the Suns atmosphere.
The History, Electrocardiogram (ECG), Age, Risk Factors, and Troponin (HEART) score is a decision aid designed to risk stratify emergency department (ED) patients with acute chest pain. It has been validated for ED use, but it has yet to be evaluated in a prehospital setting.
A prehospital modified HEART score can predict major adverse cardiac events (MACE) among undifferentiated chest pain patients transported to the ED.
A retrospective cohort study of patients with chest pain transported by two county-based Emergency Medical Service (EMS) agencies to a tertiary care center was conducted. Adults without ST-elevation myocardial infarction (STEMI) were included. Inter-facility transfers and those without a prehospital 12-lead ECG or an ED troponin measurement were excluded. Modified HEART scores were calculated by study investigators using a standardized data collection tool for each patient. All MACE (death, myocardial infarction [MI], or coronary revascularization) were determined by record review at 30 days. The sensitivity and negative predictive values (NPVs) for MACE at 30 days were calculated.
Over the study period, 794 patients met inclusion criteria. A MACE at 30 days was present in 10.7% (85/794) of patients with 12 deaths (1.5%), 66 MIs (8.3%), and 12 coronary revascularizations without MI (1.5%). The modified HEART score identified 33.2% (264/794) of patients as low risk. Among low-risk patients, 1.9% (5/264) had MACE (two MIs and three revascularizations without MI). The sensitivity and NPV for 30-day MACE was 94.1% (95% CI, 86.8-98.1) and 98.1% (95% CI, 95.6-99.4), respectively.
Prehospital modified HEART scores have a high NPV for MACE at 30 days. A study in which prehospital providers prospectively apply this decision aid is warranted.
There is increased interest, in using sugar beet pulp (SBP) products in equine diets as a major source of fibre in place of traditional forages. It has been observed that voluntary feed intake (VFI) was lower when SBP products were included in the diet of dry sows compared to other fibrous foodstuffs (Brouns, et al 1995). Equids are similar to pigs in respect that fibrous feed components must pass through the stomach and small intestine before reaching the hindgut; the primary site of fibre fermentation. This study examines the VFI and apparent digestibility in vivo of two SBP based diets and determines their ability to meet the predicted energy and protein needs of mature ponies.
Five mature Welsh-cross and three mature Shetland pony geldings with a mean liveweight (LW) of 219 kg (s.e.d. 2.2) were individually housed and offered 2 kg/d dry matter (DM) of a mature threshed grass hay (THAY), 60 g/h/d minerals and ad libitum access to either soaked molassed sugar beet pulp (MSBP) or soaked unmolassed sugar beet pulp (USBP).
There has been rising interest followed by extensive research on organic and polymer solar cells in the last three decades. Organic semiconductors have made great strides since conductivity  and electroluminescence  in Anthracene were studied in the 1960s by Kallmann and his group. Electronic processes in organic materials have been thoroughly discussed by Pope and Swinberg . Rapid progress in the field of organic materials is exemplified by the commercial success of Organic Light Emitting Diodes (OLEDS) in mobile phones and other applications. This has been possible through the tailor-making of the properties of organic semiconductors to emit light across the visible spectrum from blue to red . Recently Heliatek , a German firm, has achieved a record conversion efficiency of 13.2% for an Organic Photovoltaic (OPV) Multi-junction (MJ) cell using small molecules. The cell has three absorber layers for absorbing light from the near infrared, red and green wavelengths, covering the major part of the solar spectrum from 450 nm to 950 nm. Stability of the small molecules is projected for 25 years. This achievement has provided great impetus to commercial development. Thus, there is, in principle, no reason why organic solar cells with their inherent advantages, discussed below, should not usher in the third generation of solar cells [6, 7].
At the outset it is necessary to distinguish between the types of organic and polymer materials for PV applications.
Organic semiconductors can be classified into two broad types :
(a) Small molecules with molecular weight (MW) < 1000; usually deposited by physical vapour deposition
(b) Polymeric films with molecular weight (MW) > 10,000; deposited by casting from solution, spin coating, doctor blading screen, or inkjet printing. Though thin films are reasonably easy to form, their molecular weight and purity are hard to control.
Organic solids and polymers are generally considered to be insulators. However, both, the small molecules and polymers (Figure 5.1) used as light-absorbing materials have large conjugated systems in which carbon atoms covalently bond with alternating single and double bonds. These electrons in orbitals delocalize and form a delocalized bonding orbital with a anti-bonding orbital. The delocalized orbital forms the Highest Occupied Molecular Orbital (HOMO) and the orbital forms the Lowest Unoccupied Molecular Orbital (LUMO).
Our conventional energy reserves are limited and have severe environmental impact. There has been all round focus on the development of renewable energy primarily due to these facts, as well as from the perspective of energy security, climate change and energy access. Solar energy has been the Earth's most available energy source, capable of providing many times the total energy demand. Solar Photovoltaic (SPV) deals with conversion of sunlight into electricity. Governments across the world have realized the importance of solar power and over 60 countries have introduced feed-in tariffs, capital subsidies and incentives for productions to promote wider adoption and advancement of SPV. The average growth rate of global SPV capacity has been close to 40%, with the total installed capacity now approaching 350GWP. Renewable energy initiatives, particularly SPV, have picked up pace in India also. The Jawaharlal Nehru National Solar Mission (JNNSM) has been a major initiative of the Government of India to give an impetus to the domestic solar power industry. It sets an ambitious target of 20 GW of solar power capacity by 2022. Several State Governments have announced independent policies in SPV.
Solar PV systems [1–7] occupy a very important place in the SPV value chain (Figure 9.1). As it comes at the end point of the value chain, it decides the amount of power finally supplied. The power generated by a SPV system depends on the previous operations of the value chain as well. In the crystalline silicon (c-Si) technology, the type of wafers (mono or multi) and the efficiency of the solar cells, decided by the cell manufacturing technology, play a very important role. Assembly of the solar cells to make modules has been somewhat straightforward for c-Si technology. Thin film technology (a-Si, CdTe, CIGS, etc.) takes a different route in the value chain diagram (Figure 9.1). The modules are made directly by the Chemical Vapour Deposition (CVD) technique to deposit thin layers of appropriate materials on a conductive glass substrate to form p-n junction solar cell. In this case also the efficiency is decided by several factors such as material (Si, CdTe, CIGS, etc.), structure (amorphous, microcrystalline, etc.) and configuration (single junction, tandem junction, etc.).
Solar photovoltaics (SPV) forms an integral part of renewable energy systems that are crucial for combating global warming. Written to serve as an ideal text for students, researchers and industrial personnel, it discusses the principles of operation of photovoltaic devices, their limitations, choice of materials, and maximum efficiencies. It covers in depth discussion of new materials and devices based on organics and perovskites, and a flow-chart of the manufacture of Si, GaAs and CdTe cells, their characterization and testing. It highlights characterization, testing and reliability of solar PV modules, comparison of fixed and tracking SPV systems using concentrator cells. Economical aspects of grid-connected and stand-alone systems and a wide range of applications, from solar pumps, and street lighting to large power plants is covered in the text. Several aspects such as cell and module manufacture, characterization, testing, reliability, and system design are described considering commercial SPV manufacturing plants.
Solar Photovoltaic (SPV) modules occupy an important position in the value chain [1–5] (see Figure 9.1). Crystalline silicon (c-Si) is currently the preferred technology with a market share of about 85%. c-Si modules are made using crystalline silicon (Si) solar cells as the starting material. Several such cells are connected to make modules. The manufacturing process for c-Si modules is less complex than that for thin film modules. However, the value chain is quite long (see Figure 9.1) and more process steps in cell manufacture are required prior to module manufacturing. There are also processes, such as single crystal growth in the value chain, which require a substantial amount of electrical energy.
Thin film modules are made with an entirely different approach. These modules are made using a full size substrate (actually superstrate), typically glass with transparent conductive coating and use deposition techniques such as Plasma Enhanced Chemical Vapour Deposition (PECVD). For a-Si cells, layers of p, i and n are deposited sequentially to form the junction for PV conversion. Expensive and energy-intensive crystal growth required in c-Si technology is thus avoided. Historically, CdS/Cu2S were the first thin film cells invented in 1954. But, these were not commercially successful due to low efficiencies and degradation with time. Nowadays semiconductors such as amorphous Si (a-Si), CdTe or CIGS are used in thin film cells. Amorphous-silicon uses PECVD deposited a-Si as the active material. Single, as well as tandem junction a-Si films can be used to form a SPV module. A composite technology using a combination of a-Si and c-Si, called Heterojunction with Intrinsic Thin Layer (HIT) has also been developed. Cadmium Telluride (CdTe) and Copper Indium Gallium Selenide (CIGS) are the other two thin film materials that are being used for commercial SPV technology. Thin film technology has a much shorter value chain with lower electricity consumption than c-Si technology, PECVD being the only complex process. The cost per WP and payback period of thin film technologies is therefore lower than for c-Si technology. Another difference is that the temperature co-efficient of power output is less for thin film cells. This is an advantage in a tropical country such as India. Nevertheless, c-Si is still preferred due to higher efficiency and reliability.