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"Huts."
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Making shelter
This book provides tips for building shelters in the wild, including using natural means in different regions such as the desert, forest, jungle, and cold areas.
Book
Ultrafast coherent control of a hole spin qubit in a germanium quantum dot
Operation speed and coherence time are two core measures for the viability of a qubit. Strong spin-orbit interaction (SOI) and relatively weak hyperfine interaction make holes in germanium (Ge) intriguing candidates for spin qubits with rapid, all-electrical coherent control. Here we report ultrafast single-spin manipulation in a hole-based double quantum dot in a germanium hut wire (GHW). Mediated by the strong SOI, a Rabi frequency exceeding 540 MHz is observed at a magnetic field of 100 mT, setting a record for ultrafast spin qubit control in semiconductor systems. We demonstrate that the strong SOI of heavy holes (HHs) in our GHW, characterized by a very short spin-orbit length of 1.5 nm, enables the rapid gate operations we accomplish. Our results demonstrate the potential of ultrafast coherent control of hole spin qubits to meet the requirement of DiVincenzo’s criteria for a scalable quantum information processor.
Hole-spin qubits in germanium are promising candidates for rapid, all-electrical qubit control. Here the authors report Rabi oscillations with the record frequency of 540 MHz in a hole-based double quantum dot in a germanium hut wire, which is attributed to strong spin-orbit interaction of heavy holes.
Journal Article
Seeing Red
Red's temper has put him in hot water or out of a job, but he has to work in order to build his dream hut.
Book
Dipole coupling of a hole double quantum dot in germanium hut wire to a microwave resonator
The germanium (Ge) hut wire system has strong spin-orbit coupling, a long coherence time due to a very large heavy-light hole splitting, and the advantage of site-controlled large-scale hut wire positioning. These properties make the Ge hut wire a promising candidate for the realization of strong coupling of spin to superconducting resonators and scalability for multiple qubit coupling. We have coupled a reflection line resonator to a hole double quantum dot (DQD) formed in Ge hut wire. The amplitude and phase responses of the microwave resonator revealed that the charge stability diagrams of the DQD are in good agreement with those obtained from transport measurements. The DQD interdot tunneling rate is shown to be tunable from 6.2 GHz to 8.5 GHz, which demonstrates the ability to adjust the frequency detuning between the qubit and the resonator. Furthermore, we achieved a hole-resonator coupling strength of up to 15 MHz, with a charge qubit decoherence rate of 0.28 GHz. Meanwhile the hole spin-resonator coupling rate was estimated to be 3 MHz. These results suggest that holes of a DQD in a Ge hut wire are dipole coupled to microwave photons, potentially enabling tunable hole spin-photon interactions in Ge with an inherent spin-orbit coupling.
Journal Article
Efficacy of Fludora® Fusion (a mixture of deltamethrin and clothianidin) for indoor residual spraying against pyrethroid-resistant malaria vectors: laboratory and experimental hut evaluation
Background
A new generation of IRS insecticides which can provide improved and prolonged control of pyrethroid-resistant malaria vector populations are being developed. Fludora® Fusion is a new IRS insecticide containing a mixture of deltamethrin and clothianidin, a neonicotinoid.
Methods
The efficacy of Fludora® Fusion IRS was evaluated over 11–12 months on concrete and mud substrates in laboratory bioassays and experimental huts against wild free-flying pyrethroid-resistant
Anopheles gambiae
(
sensu lato
) in Cové, Benin. A comparison was made with the two active ingredients of the mixture; clothianidin and deltamethrin, applied alone. CDC bottle bioassays were also performed to investigate resistance to clothianidin in the wild vector population.
Results
Fludora® Fusion induced > 80% laboratory cone bioassay mortality with both susceptible and pyrethroid-resistant
An. gambiae
(
s.l.
) for 7–9 months on concrete block substrates and 12 months on mud block substrates. The vector population at the experimental hut site was fully susceptible to clothianidin in CDC bottle bioassays. Overall mortality rates of wild free-flying pyrethroid-resistant
An. gambiae
(
s.l.
) entering the experimental huts during the 11-month trial were < 15% with deltamethrin and significantly higher with Fludora® Fusion (69–71%) and clothianidin alone (72–78%). Initial high experimental hut mortality rates with Fludora® Fusion (> 80%) only declined by 50% after 8 months. Monthly
in situ
wall cone bioassay mortality of susceptible mosquitoes was > 80% for 9–12 months with Fludora® Fusion and clothianidin alone. Fludora® Fusion induced significantly higher levels of early exiting of mosquitoes compared to clothianidin alone (55–60% vs 37–38%,
P
< 0.05).
Conclusions
Indoor residual spraying with Fludora® Fusion induced high and prolonged mortality of wild pyrethroid-resistant malaria vectors for 7–10 months mostly due to the clothianidin component and substantial early exiting of mosquitoes from treated huts due to the pyrethroid component. Fludora® Fusion is an important addition to the current portfolio of IRS insecticides with the potential to significantly reduce transmission of malaria by pyrethroid-resistant mosquito vectors.
Journal Article
Efficacy of 3D screens for sustainable mosquito control: a semi-field experimental hut evaluation in northeastern Tanzania
Background
A three-dimensional window screen (3D-Screen) has been developed to create a window double-screen trap (3D-WDST), effectively capturing and preventing the escape of mosquitoes. A 2015 laboratory study demonstrated the 3D-Screen's efficacy, capturing 92% of mosquitoes in a double-screen setup during wind tunnel assays. To further evaluate its effectiveness, phase II experimental hut trials were conducted in Muheza, Tanzania.
Methods
Three experimental hut trials were carried out between 2016 and 2017. Trial I tested two versions of the 3D-WDST in huts with open or closed eaves, with one version using a single 3D-Screen and the other using two 3D-Screens. Trial II examined the 3D-WDST with two 3D-Screens in huts with or without baffles, while Trial III compared handmade and machine-made 3D structures. Mosquito capturing efficacy of the 3D-WDST was measured by comparing the number of mosquitoes collected in the test hut to a control hut with standard exit traps.
Results
Trial I showed that the 3D-WDST with two 3D-Screens used in huts with open eaves achieved the highest mosquito-capturing efficacy. This treatment captured 33.11% (CI 7.40–58.81) of female anophelines relative to the total collected in this hut (3D-WDST and room collections) and 27.27% (CI 4.23–50.31) of female anophelines relative to the total collected in the control hut (exit traps, room, and verandahs collections). In Trial II, the two 3D-Screens version of the 3D-WDST captured 70.32% (CI 56.87–83.77) and 51.07% (CI 21.72–80.41) of female anophelines in huts with and without baffles, respectively. Compared to the control hut, the capturing efficacy for female anophelines was 138.6% (37.23–239.9) and 42.41% (14.77–70.05) for huts with and without baffles, respectively. Trial III demonstrated similar performance between hand- and machine-made 3D structures.
Conclusions
The 3D-WDST proved effective in capturing malaria vectors under semi-field experimental hut conditions. Using 3D-Screens on both sides of the window openings was more effective than using a single-sided 3D-Screen. Additionally, both hand- and machine-made 3D structures exhibited equally effective performance, supporting the production of durable cones on an industrial scale for future large-scale studies evaluating the 3D-WDST at the community level.
Graphical Abstract
Journal Article
Relative performance of indoor vector control interventions in the Ifakara and the West African experimental huts
Background
West African and Ifakara experimental huts are used to evaluate indoor mosquito control interventions, including spatial repellents and insecticides. The two hut types differ in size and design, so a side-by-side comparison was performed to investigate the performance of indoor interventions in the two hut designs using standard entomological outcomes: relative indoor mosquito density (deterrence), exophily (induced exit), blood-feeding and mortality of mosquitoes.
Methods
Metofluthrin mosquito coils (0.00625% and 0.0097%) and Olyset® Net
vs
control nets (untreated, deliberately holed net) were evaluated against pyrethroid-resistant
Culex quinquefasciatus
in Benin. Four experimental huts were used: two West African hut designs and two Ifakara hut designs. Treatments were rotated among the huts every four nights until each treatment was tested in each hut 52 times. Volunteers rotated between huts nightly.
Results
The Ifakara huts caught a median of 37
Culex quinquefasciatus
/ night, while the West African huts captured a median of 8/ night (rate ratio 3.37, 95% CI: 2.30–4.94,
P
< 0.0001) and this difference in mosquito entry was similar for Olyset® Net and more pronounced for spatial repellents. Exophily was greater in the Ifakara huts with > 4-fold higher mosquito exit relative to the West African huts (odds ratio 4.18, 95% CI: 3.18–5.51,
P
< 0.0001), regardless of treatment. While blood-feeding rates were significantly higher in the West African huts, mortality appeared significantly lower for all treatments.
Conclusions
The Ifakara hut captured more
Cx. quinquefasciatus
that could more easily exit into windows and eave traps after failing to blood-feed, compared to the West African hut. The higher mortality rates recorded in the Ifakara huts could be attributable to the greater proportions of
Culex
mosquitoes exiting and probably dying from starvation, relative to the situation in the West African huts.
Journal Article
Improvement to East African style experimental huts allows for more effective evaluation of vector control products for protection against vector-borne diseases
BackgroundEast African style experimental huts have been used in Tanzania since 1963 to evaluate vector control interventions such as insecticide-treated nets and indoor residual spraying. Over time, these huts have been modified to include eave baffles to minimise mosquito escape. In this study, we evaluated the impact of increasing baffle size and using netting to funnel mosquito entry into the room and prevent escape. We also explored mosquito entry behaviour using a sticky trap positioned on the hut exterior to determine if this behaviour could be leveraged for vector control.MethodsThis study was conducted in Moshi, Tanzania and included two trials. In trial one, we compared the original huts with baffles with small exit holes (4 × 110 cm at the wide end nearest the eave gap and 2 × 2 cm at the narrow funnel end) to those with a larger size of baffle exit hole (20 × 120 cm at the wide end and 4 × 10 cm at the narrow end). In trial two, we compared huts with a sticky trap on the exterior wall to those without. Data analyses used logistic regression models to compare mosquito entry, blood-feeding rates and exophily, adjusting for variation between huts, cows (for blood-feeding) and days of the trial.ResultsLarger eave baffles significantly increased entry of Anopheles gambiae Kisumu mosquitoes into huts [p = 0.01, adjusted odds ratio (AOR) 2.1, 95% confidence interval (CI) 1.2–3.8]. Blood-feeding rates were also significantly higher in huts with the larger baffle size compared to those with the original baffle size [p = 0.001, AOR 16.9 95% CI 4.9–59.0]. In trial two, 16% (95 CI 13.3–19.6) of An. gambiae Kisumu and 8% (95 CI: 6.3–10.5) of Anopheles arabiensis populations were collected on the sticky traps, significantly reducing mosquito entry into huts. With the presence of sticky traps, blood-feeding was inhibited by 12.7% for An. arabiensis and 32.6% for An. gambiae Kisumu.ConclusionsThe results of this study support the use of larger baffle sizes in East African huts to capture larger numbers of mosquitoes and improve the evaluation of vector control tools. Although only a small proportion of mosquitoes were found to have had direct contact with the exterior of the hut before entry, the presence of sticky traps still reduced blood-feeding rates by limiting the entry of host-seeking mosquitoes.
Journal Article
Inferring the epidemiological benefit of indoor vector control interventions against malaria from mosquito data
The cause of malaria transmission has been known for over a century but it is still unclear whether entomological measures are sufficiently reliable to inform policy decisions in human health. Decision-making on the effectiveness of new insecticide-treated nets (ITNs) and the indoor residual spraying of insecticide (IRS) have been based on epidemiological data, typically collected in cluster-randomised control trials. The number of these trials that can be conducted is limited. Here we use a systematic review to highlight that efficacy estimates of the same intervention may vary substantially between trials. Analyses indicate that mosquito data collected in experimental hut trials can be used to parameterize mechanistic models for
Plasmodium falciparum
malaria and reliably predict the epidemiological efficacy of quick-acting, neuro-acting ITNs and IRS. Results suggest that for certain types of ITNs and IRS using this framework instead of clinical endpoints could support policy and expedite the widespread use of novel technologies.
Estimating the effectiveness of malaria vector control interventions has typically relied on resource-intensive cluster randomised trials. Here, the authors estimate changes in malaria prevalence using entomological data from experimental hut trials, which may provide an alternative route to approval of interventions in some situations.
Journal Article
Indoor residual spraying with a mixture of clothianidin (a neonicotinoid insecticide) and deltamethrin provides improved control and long residual activity against pyrethroid resistant Anopheles gambiae sl in Southern Benin
There is an urgent need for new insecticides for indoor residual spraying (IRS) which can provide improved and prolonged control of malaria vectors that have developed resistance to existing insecticides. The neonicotinoid, clothianidin represents a class of chemistry new to public health. Clothianidin acts as an agonist on nicotinic acetyl choline receptors. IRS with a mixture of Clothianidin and another WHO approved insecticide such as deltamethrin could provide improved control of insecticide resistant malaria vector populations and serve as a tool for insecticide resistance management.
The efficacy and residual activity of a novel IRS mixture of deltamethrin and clothianidin was evaluated against wild pyrethroid resistant An. gambiae sl in experimental huts in Cove, Benin. Two application rates of the mixture were tested and comparison was made with clothianidin and deltamethrin applied alone. To assess the residual efficacy of the treatments on different local wall substrates, the inner walls of the experimental huts were covered with either cement, mud or plywood.
Clothianidin demonstrated a clear delayed expression in mortality of wild pyrethroid resistant An. gambiae sl in the experimental huts which reached its full effect 120 hours after exposure. Overall mortality over the 12-month hut trial was 15% in the control hut and 24-29% in the deltamethrin-treated huts. The mixture of clothianidin 200mg/m2 and deltamethrin 25mg/m2 induced high overall hut mortality rates (87% on mud walls, 82% on cement walls and 61% on wooden walls) largely due to the clothianidin component and high hut exiting rates (67-76%) mostly due to the deltamethrin component. Mortality rates remained >80% for 8-9 months on mud and cement walls. The residual activity trend was confirmed by results from monthly in situ cone bioassays with laboratory susceptible An. gambiae Kisumu strain.
IRS campaigns with the mixture of clothianidin plus deltamethrin have the potential to provide prolonged control of malaria transmitted by pyrethroid resistant mosquito populations.
Journal Article