When examining how the ecosystems of remote islands have developed, it is important to know the timing of when various elements arrived and whether they then diversified. Our understanding of the ...histories behind the biodiverse south west Pacific (SWP) archipelagos is limited, and further impeded by the complex geological histories of this region. Previous studies of the SWP short-tongued halictine bee fauna suggest their presence is much younger than the geological ages of these archipelagos, which is surprising given their critical role as pollinators in other terrestrial ecosystems. The long-tongued megachilid bees represent a considerable proportion of the known bee species for the region, yet little is known of their origin. Here we use genetic diversity within mitochondrial DNA to infer the likely ages and origins of megachilid species from Vanuatu, Fiji, and Samoa. Our results indicate a very recent origin for megachilids in the SWP, with many species exhibiting small intraspecific genetic distances. Three species share almost identical haplotypes with specimens from Southeast Asia, suggesting multiple human-aided introductions. Combined with data from recent studies on other bee groups present in the region, our results have broad implications for how the Pacific island biota developed and how we should approach its management.
INTRODUCTION/ PURPOSE: The widespread occurrence of muscular atrophy during immobilization and its reversal presents an important challenge to rehabilitation medicine. We used 3D-magnetic resonance ...imaging (MRI) in patients with surgically-stabilized ankle mortise fractures to quantify changes in plantarflexor and dorsiflexor muscle size during immobilization and rehabilitation, as well as to evaluate changes in force generating capacity (specific torque).
Twenty-individuals participated in a 10 wk rehabilitation program after 7 wk of immobilization. MRIs were acquired at baseline, 2, and 7 wk of immobilization, and at 5 and 10 wk of rehabilitation. Isometric plantarflexor muscle strength testing was performed at 0, 5, and 10 wk of rehabilitation.
Dorsiflexors and plantarflexors atrophied 18.9% and 24.4% respectively, the majority of which occurred during the first 2 wk of immobilization (dorsiflexors: 9.6%; plantarflexors: 14.1%). Likewise, more than 50% of hypertrophy during rehabilitation occurred within the first 5 wk of rehabilitation for both the dorsiflexors (12.9%) and plantarflexors (13.2%), when compared to the total amount of hypertrophy over 10 wk of rehabilitation (dorsiflexors: 17.6%, plantarflexors: 22.5%). There were no significant differences in hypertrophy or atrophy of the dorsiflexor or plantarflexor muscles, despite a rehabilitation emphasis on the plantarflexors. Patients had significantly lower plantarflexor specific torque (torque/CSA) than healthy, control subjects immediately after cast immobilization, which did not return to normal after 10 wk of rehabilitation (P < 0.05).
Our investigation of the consequences of limb immobilization on rehabilitation outcomes in patients can be applied directly to optimizing rehabilitation programs. Although muscle hypertrophy occurred early during rehabilitation, plantarflexor muscle function (specific torque) should remain the focus of rehabilitation programs because although CSA recovered quickly, specific torque still lagged behind that of control subjects.
Abstract
Colletidae is a predominantly southern hemisphere bee family with a
L
ate
C
retaceous origin and with an inferred ancestral region covering late
G
ondwanan
S
outh
A
merica,
A
ntarctica and
A
...ustralia. One highly diverse colletid subfamily,
E
uryglossinae, is entirely restricted to
A
ustralia and the strictly
A
frotropical subfamily
S
crapterinae has been inferred as its sister clade. This has led to suggestions that
S
crapterinae represents a highly unusual post‐
G
ondwanan dispersal from
A
ustralia to
A
frica, but phylogenetic studies to date have included only minimal representatives from each subfamily. Here we greatly increase the level of species sampling of both subfamilies and develop a molecular phylogeny based on one mitochondrial and two nuclear genes. Our results indicate that the broad results of earlier studies are robust to substantially greater taxon sampling, and we infer a divergence date between the two subfamilies in the early
E
ocene. Dispersal pathways between
A
frica and
A
ustralia during that time are problematic, with several studies suggesting dispersals via the now largely submerged
K
erguelen and
C
rozet
P
lateaus. Our results contribute another example of a puzzling sister‐clade relationship between
A
frican and
A
ustralian taxa and indicate the need to better understand southern hemisphere subaerial configurations, including
A
ntarctica, and ocean and wind currents at those times.
The Central Limit Theorem (CLT) is a statistical principle that states that as the number of repeated samples from any population increase, the variance among sample means will decrease and means ...will become more normally distributed. It has been conjectured that the CLT has the potential to provide benefits for group living in some animals via greater predictability in food acquisition, if the number of foraging bouts increases with group size. The potential existence of benefits for group living derived from a purely statistical principle is highly intriguing and it has implications for the origins of sociality.
Here we show that in a social allodapine bee the relationship between cumulative food acquisition (measured as total brood weight) and colony size accords with the CLT. We show that deviations from expected food income decrease with group size, and that brood weights become more normally distributed both over time and with increasing colony size, as predicted by the CLT. Larger colonies are better able to match egg production to expected food intake, and better able to avoid costs associated with producing more brood than can be reared while reducing the risk of under-exploiting the food resources that may be available.
These benefits to group living derive from a purely statistical principle, rather than from ecological, ergonomic or genetic factors, and could apply to a wide variety of species. This in turn suggests that the CLT may provide benefits at the early evolutionary stages of sociality and that evolution of group size could result from selection on variances in reproductive fitness. In addition, they may help explain why sociality has evolved in some groups and not others.
Cover Image Grandidier, Jonathan; Kirk, Alexander P.; Jahelka, Phillip ...
Progress in photovoltaics,
June 2020, Letnik:
28, Številka:
6
Journal Article
Recenzirano
The cover image is based on the EU PVSEC Paper Photovoltaic operation in the lower atmosphere and at the surface of Venus by Jonathan Grandidier at al., https://doi.org/10.1002/pip.3214.
Prior sexual trauma (ST) is associated with greater risk for posttraumatic stress disorder after a subsequent traumatic event; however, the underlying neurobiological mechanisms remain opaque. We ...investigated longitudinal posttraumatic dysfunction and amygdala functional dynamics following admission to an emergency department for new primarily nonsexual trauma in participants with and without previous ST.
Participants (N = 2178) were recruited following acute trauma exposure (primarily motor vehicle collision). A subset (n = 242) completed magnetic resonance imaging that included a fearful faces task and a resting-state scan 2 weeks after the trauma. We investigated associations between prior ST and several dimensions of posttraumatic symptoms over 6 months. We further assessed amygdala activation and connectivity differences between groups with or without prior ST.
Prior ST was associated with greater posttraumatic depression (F1,1120 = 28.35, p = 1.22 × 10−7, ηp2 = 0.06), anxiety (F1,1113 = 17.43, p = 3.21 × 10−5, ηp2 = 0.05), and posttraumatic stress disorder (F1,1027 = 11.34, p = 7.85 × 10−4, ηp2 = 0.04) severity and more maladaptive beliefs about pain (F1,1113 = 8.51, p = .004, ηp2 = 0.02) but was not related to amygdala reactivity to fearful versus neutral faces (all ps > .05). A secondary analysis revealed an interaction between ST and lifetime trauma load on the left amygdala to visual cortex connectivity (peak Z value: −4.41, corrected p < .02).
Findings suggest that prior ST is associated with heightened posttraumatic dysfunction following a new trauma exposure but not increased amygdala activity. In addition, ST may interact with lifetime trauma load to alter neural circuitry in visual processing regions following acute trauma exposure. Further research should probe the relationship between trauma type and visual circuitry in the acute aftermath of trauma.
The optimal sequencing of antiretroviral regimens for the treatment of infection with human immunodeficiency virus type 1 (HIV-1) is unknown. We compared several different antiretroviral treatment ...strategies.
This multicenter, randomized, partially double-blind trial used a factorial design to compare pairs of sequential three-drug regimens, starting with a regimen including zidovudine and lamivudine or a regimen including didanosine and stavudine in combination with either nelfinavir or efavirenz. The primary end point was the length of time to the failure of the second three-drug regimen.
A total of 620 subjects who had not previously received antiretroviral therapy were followed for a median of 2.3 years. Starting with a three-drug regimen containing efavirenz combined with zidovudine and lamivudine (but not efavirenz combined with didanosine and stavudine) appeared to delay the failure of the second regimen, as compared with starting with a regimen containing nelfinavir (hazard ratio for failure of the second regimen, 0.71; 95 percent confidence interval, 0.48 to 1.06), as well as to delay the second virologic failure (hazard ratio, 0.56; 95 percent confidence interval, 0.29 to 1.09), and significantly delayed the failure of the first regimen (hazard ratio, 0.39) and the first virologic failure (hazard ratio, 0.34). Starting with zidovudine and lamivudine combined with efavirenz (but not zidovudine and lamivudine combined with nelfinavir) appeared to delay the failure of the second regimen, as compared with starting with didanosine and stavudine (hazard ratio, 0.68), and significantly delayed both the first and the second virologic failures (hazard ratio for the first virologic failure, 0.39; hazard ratio for the second virologic failure, 0.47), as well as the failure of the first regimen (hazard ratio, 0.35). The initial use of zidovudine, lamivudine, and efavirenz resulted in a shorter time to viral suppression.
The efficacy of antiretroviral drugs depends on how they are combined. The combination of zidovudine, lamivudine, and efavirenz is superior to the other antiretroviral regimens used as initial therapy in this study.
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