The economic viability and energy use of vertical farms strongly depend on the efficiency of the use of light. Increasing far-red radiation (FR, 700–800 nm) relative to photosynthetically active radiation (PAR, 400–700 nm) may induce shade avoidance responses including stem elongation and leaf expansion, which would benefit light interception, and FR might even be photosynthetically active when used in combination with PAR. The aims of this study are to investigate the interaction between FR and planting density and to quantify the underlying components of the FR effects on growth. Lettuce (Lactuca sativa cv. Expertise RZ) was grown in a climate chamber under two FR treatments (0 or 52 μmol m–2 s–1) and three planting densities (23, 37, and 51 plants m–2). PAR of 89% red and 11% blue was kept at 218 μmol m–2 s–1. Adding FR increased plant dry weight after 4 weeks by 46–77% (largest effect at lowest planting density) and leaf area by 58–75% (largest effect at middle planting density). Radiation use efficiency (RUE: plant dry weight per unit of incident radiation, 400–800 nm) increased by 17–42% and incident light use efficiency (LUEinc: plant dry weight per unit of incident PAR, 400–700 nm) increased by 46–77% by adding FR; the largest FR effects were observed at the lowest planting density. Intercepted light use efficiency (LUEint: plant dry weight per unit of intercepted PAR) increased by adding FR (8–23%). Neither specific leaf area nor net leaf photosynthetic rate was influenced by FR. We conclude that supplemental FR increased plant biomass production mainly by faster leaf area expansion, which increased light interception. The effects of FR on plant dry weight are stronger at low than at high planting density. Additionally, an increased LUEint may contribute to the increased biomass production.
Vertical farming is a relatively new fresh fruit and vegetable production system, where lamps (mostly light emitting diodes [LED]) are the sole light source. A high light use efficiency (LUEinc), defined as shoot dry weight per incident photosynthetic photon flux density (PPFD; g mol−1) integral, is crucial for the economic viability of vertical farming. Very different values for LUEinc have been reported in the literature and it is not clear whether LUEinc is higher in vertical farming than in greenhouse or open field cultivation. Values of LUEinc of lettuce grown in a vertical farm (53 studies), greenhouse (13 studies) and open field (8 studies) were collected from literature, as well as relevant cultivation aspects such as lettuce weight at harvest, cultivation period (plant age at harvest), daily light integral, cumulative daily light integral for the whole cultivation period, planting density and CO2 concentration. The average LUEinc for lettuce grown in a vertical farm was 0.55 g mol−1 which was higher than 0.39 g mol−1 for greenhouse‐grown lettuce. Both were substantially higher than for field‐grown lettuce (0.23 g mol−1). The maximum measured LUEinc for lettuce grown in a vertical farm (1.63 g mol−1) is close to the published maximum theoretical value, which ranges from 1.26 to 1.81 g mol−1. Since all environmental factors can be fully controlled, vertical farming has the capability to achieve the theoretical maximum LUEinc. Using the highest reported LUEinc based on shoot fresh weight (44 g mol−1 at 200 μmol m−2 s−1 PPFD and 16 h photoperiod), it is estimated that each layer of a vertical farm can potentially produce annually up to 700 kg of lettuce per m2 at 500 μmol m−2 s−1 of continuous light.
Background: Theta burst stimulation (TBS) is more energy- and time-efficient than standard repetitive transcranial magnetic stimulation (rTMS). However, further studies are needed to analyze TBS therapy for its efficacy and safety compared to standard rTMS for major depressive disorder (MDD). The aim of this meta-analysis was to compare TBS therapy and standard rTMS treatment regarding their safety and therapeutic effect on individuals with MDD.
Methods: Six databases (Wanfang, the China National Knowledge Infrastructure, PubMed, Embase, Cochrane Library, and PsycINFO) were searched from inception till November 20, 2022. Two independent reviewers selected potentially relevant studies based on the inclusion criteria, extracted data, and evaluated the methodological quality of the eligible trials using the modified 10-item Physiotherapy Evidence Database scale per PRISMA guidelines.
Finally, ten comparable pairs of 9 randomized controlled trials were included for meta-analysis. Summary odds ratios (ORs) of the rates of response, remission, and adverse events were simultaneously calculated using quality-effects (QE) and random-effects (RE) models. Changes in depression scores associated with antidepressant effects were expressed using standardized mean differences (SMDs) simultaneously. This study was registered with PROSPERO (CRD42022376790).
Results: Nine of the 602 RCTs, covering 1196 cases (616 subjected to TBS protocols vs. 580 treated using standard rTMS), were enrolled. Differences in response rates between the above two treatment modalities were not significant (OR = 1.03, 95% CI: 0.90–1.18, P > 0.05, I2 = 4%, RE model; OR = 1.09, 95% CI: 0.90–1.32, P > 0.05, I2 = 4%, QE model). Differences in adverse event rates between TBS and standard rTMS groups were not statistically significant.
Conclusion: TBS has similar efficacy and safety as standard rTMS for treating MDD. In light of the short duration of daily stimulation sessions, this meta-analysis supports the continued development of TBS for treating depression.
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