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1.
Phys Rev Lett ; 132(6): 062702, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38394565

RESUMO

The cross section of the ^{13}C(α,n)^{16}O reaction is needed for nuclear astrophysics and applications to a precision of 10% or better, yet inconsistencies among 50 years of experimental studies currently lead to an uncertainty of ≈15%. Using a state-of-the-art neutron detection array, we have performed a high resolution differential cross section study covering a broad energy range. These measurements result in a dramatic improvement in the extrapolation of the cross section to stellar energies potentially reducing the uncertainty to ≈5% and resolving long standing discrepancies in higher energy data.

2.
Microbiol Resour Announc ; 12(10): e0054223, 2023 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-37747416

RESUMO

A whole genome sequence of a Paenibacillus sp. bacterium isolated from soil in Fort Collins, Colorado was obtained. This bacterium was of particular interest due to its antibiotic potential against Gram-positive pathogen surrogates.

3.
J Immunother Cancer ; 10(9)2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36167468

RESUMO

BACKGROUND: Aggressive primary brain tumors such as glioblastoma are uniquely challenging to treat. The intracranial location poses barriers to therapy, and the potential for severe toxicity. Effective treatments for primary brain tumors are limited, and 5-year survival rates remain poor. Immune checkpoint inhibitor therapy has transformed treatment of some other cancers but has yet to significantly benefit patients with glioblastoma. Early phase trials of chimeric antigen receptor (CAR) T-cell therapy in patients with glioblastoma have demonstrated that this approach is safe and feasible, but with limited evidence of its effectiveness. The choices of appropriate target antigens for CAR-T-cell therapy also remain limited. METHODS: We profiled an extensive biobank of patients' biopsy tissues and patient-derived early passage glioma neural stem cell lines for GD2 expression using immunomicroscopy and flow cytometry. We then employed an approved clinical manufacturing process to make CAR- T cells from patients with peripheral blood of glioblastoma and diffuse midline glioma and characterized their phenotype and function in vitro. Finally, we tested intravenously administered CAR-T cells in an aggressive intracranial xenograft model of glioblastoma and used multicolor flow cytometry, multicolor whole-tissue immunofluorescence and next-generation RNA sequencing to uncover markers associated with effective tumor control. RESULTS: Here we show that the tumor-associated antigen GD2 is highly and consistently expressed in primary glioblastoma tissue removed at surgery. Moreover, despite patients with glioblastoma having perturbations in their immune system, highly functional GD2-specific CAR-T cells can be produced from their peripheral T cells using an approved clinical manufacturing process. Finally, after intravenous administration, GD2-CAR-T cells effectively infiltrated the brain and controlled tumor growth in an aggressive orthotopic xenograft model of glioblastoma. Tumor control was further improved using CAR-T cells manufactured with a clinical retroviral vector encoding an interleukin-15 transgene alongside the GD2-specific CAR. These CAR-T cells achieved a striking 50% complete response rate by bioluminescence imaging in established intracranial tumors. CONCLUSIONS: Targeting GD2 using a clinically deployed CAR-T-cell therapy has a sound scientific and clinical rationale as a treatment for glioblastoma and other aggressive primary brain tumors.


Assuntos
Neoplasias Encefálicas , Glioblastoma , Glioma , Receptores de Antígenos Quiméricos , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/terapia , Gangliosídeos/metabolismo , Glioblastoma/genética , Glioblastoma/terapia , Glioma/metabolismo , Humanos , Inibidores de Checkpoint Imunológico , Interleucina-15/metabolismo , Receptores de Antígenos Quiméricos/genética , Receptores de Antígenos Quiméricos/metabolismo , Linfócitos T , Ensaios Antitumorais Modelo de Xenoenxerto
4.
Front Immunol ; 13: 850226, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35464424

RESUMO

Glioblastoma is the most common and aggressive form of primary brain cancer, with no improvements in the 5-year survival rate of 4.6% over the past three decades. T-cell-based immunotherapies such as immune-checkpoint inhibitors and chimeric antigen receptor T-cell therapy have prolonged the survival of patients with other cancers and have undergone early-phase clinical evaluation in glioblastoma patients. However, a major challenge for T-cell-based immunotherapy of glioblastoma and other solid cancers is T-cell infiltration into tumours. This process is mediated by chemokine-chemokine receptor and integrin-adhesion molecule interactions, yet the specific nature of the molecules that may facilitate T-cell homing into glioblastoma are unknown. Here, we have characterised chemokine receptor and integrin expression profiles of endogenous glioblastoma-infiltrating T cells, and the chemokine expression profile of glioblastoma-associated cells, by single-cell RNA-sequencing. Subsequently, chemokine receptors and integrins were validated at the protein level to reveal enrichment of receptors CCR2, CCR5, CXCR3, CXCR4, CXCR6, CD49a, and CD49d in glioblastoma-infiltrating T-cell populations relative to T cells in matched patient peripheral blood. Complementary chemokine ligand expression was then validated in glioblastoma biopsies and glioblastoma-derived primary cell cultures. Together, enriched expression of homing receptor-ligand pairs identified in this study implicate a potential role in mediating T-cell infiltration into glioblastoma. Importantly, our data characterising the migratory receptors on endogenous tumour-infiltrating T cells could be exploited to enhance the tumour-homing properties of future T-cell immunotherapies for glioblastoma.


Assuntos
Glioblastoma , Quimiocinas/metabolismo , Glioblastoma/metabolismo , Glioblastoma/terapia , Humanos , Integrinas/metabolismo , Ligantes , Subpopulações de Linfócitos T
6.
Animal ; 15(2): 100032, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33573969

RESUMO

Plant extracts have been recognized as beneficial to human health and have been evaluated as feed additive for domestic and companion animals. This study evaluated oregano and green tea extracts fed to Jersey cows from approximately 21 d before calving to 21 d after calving on milk production, milk composition, and blood metabolites as well as investigated immunological and antioxidant attributes. Twenty-four Jersey cows with 441 ±â€¯27 kg of BW, 3.5 ±â€¯0.3 of body condition score (BCS), and 2.7 ±â€¯1.8 lactations were selected at approximately 28 d before the expected parturition date and were randomly assigned to three treatments with eight cows each: without plant extracts in diet (control - CON), addition of 10 g per day of oregano extract (OR), and addition of 5 g per day of green tea extract (GT). Feed intake, BW, BCS, blood metabolites, hemogram as well as oxidative stress biomarkers were evaluated from approximately 3 weeks prepartum to 3 weeks postpartum (transition period) while milk production and composition were evaluated during the first 3 weeks of lactation. Plant extracts did not change BW, BCS, and DM intake (DMI) throughout the transition period, but OR increased in approximately 20% total digestive nutrients and metabolizable energy intake on days 15 and 16 postpartum compared with CON. In the prepartum, OR increased in 48% platelets count compared to the CON, while GT augmented in 142% eosinophils compared with CON. Oregano extract reduced the levels of reactive species in the erythrocytes in 40% during prepartum and postpartum compared with CON, while GT reduced its levels in 24 and 29% during prepartum and postpartum, respectively, when compared with CON. In the postpartum period, OR increased in 60% the carbonylated protein content compared with CON, while GT reduced in 45% the levels of reactive species in plasma compared with CON. During the postpartum, both extracts increased in 33% the concentration of reduced glutathione when compared with CON. Moreover, GT tended to decrease feed efficiency in 11% when compared with CON; OE reduced milk pH and somatic cell count when compared with CON. In conclusion, OE and GT did not expressively affect immunological attributes in blood but reduce some oxidative stress biomarkers without compromising productive traits of Jersey cows during the transition period.


Assuntos
Antioxidantes , Origanum , Animais , Bovinos , Feminino , Dieta/veterinária , Suplementos Nutricionais , Lactação , Leite , Período Pós-Parto , Chá
8.
Clin Transl Immunology ; 9(10): e1191, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33082953

RESUMO

OBJECTIVES: Targeted immunotherapies such as chimeric antigen receptor (CAR)-T cells are emerging as attractive treatment options for glioblastoma, but rely on identification of a suitable tumor antigen. We validated a new target antigen for glioblastoma, fibroblast activation protein (FAP), by undertaking a detailed expression study of human samples. METHODS: Glioblastoma and normal tissues were assessed using immunostaining, supported by analyses of published transcriptomic datasets. Short-term cultures of glioma neural stem (GNS) cells were compared to cultures of healthy astrocytes and neurons using flow cytometry. Glioblastoma tissues were dissociated and analysed by high-parameter flow cytometry and single-cell transcriptomics (scRNAseq). RESULTS: Compared to normal brain, FAP was overexpressed at the gene and protein level in a large percentage of glioblastoma tissues, with highest levels of expression associated with poorer prognosis. FAP was also overexpressed in several paediatric brain cancers. FAP was commonly expressed by cultured GNS cells but absent from normal neurons and astrocytes. Within glioblastoma tissues, the strongest expression of FAP was around blood vessels. In fact, almost every tumor vessel was highlighted by FAP expression, whereas normal tissue vessels and cultured endothelial cells (ECs) lacked expression. Single-cell analyses of dissociated tumors facilitated a detailed characterisation of the main cellular components of the glioblastoma microenvironment and revealed that vessel-localised FAP is because of expression on both ECs and pericytes. CONCLUSION: Fibroblast activation protein is expressed by multiple cell types within glioblastoma, highlighting it as an ideal immunotherapy antigen to target destruction of both tumor cells and their supporting vascular network.

9.
Rev. méd. Chile ; 148(7): 1011-1017, jul. 2020. tab, graf
Artigo em Espanhol | LILACS | ID: biblio-1139403

RESUMO

For more than a century the training of medical professionals has been organized according to the Flexnerian model, which comprises three cycles: basic, clinical and clerkship. On the other hand, the accelerated development of biomedical sciences modified the competences of the first cycle. Additionally, new skills required for medical practice, such as teamwork and innovation as a tool to solve health problems, challenged in recent years the classic paradigm of medical education. Therefore, the medical schools have developed multiple strategies to deal with it, such as curricular integration using competency-based education models, incorporating basic and clinical sciences in parallel during the curriculum, ensuring a relevant and applicable scientific knowledge throughout the training process. Although in Chile the Flexner prototype is still followed, the basic sciences are taught as single or integrated courses or using a systems approach. In this article we report a diagnosis about the local integration of fundamental sciences in medical training. We also compare our schools with those of Canada, Europe and Latin America. Recommendations aimed at modernizing medical school curricula are made.


Assuntos
Humanos , Faculdades de Medicina , Ciência/educação , Educação Médica/organização & administração , Chile , Currículo
10.
Rev Med Chil ; 148(7): 1011-1017, 2020 Jul.
Artigo em Espanhol | MEDLINE | ID: mdl-33399686

RESUMO

For more than a century the training of medical professionals has been organized according to the Flexnerian model, which comprises three cycles: basic, clinical and clerkship. On the other hand, the accelerated development of biomedical sciences modified the competences of the first cycle. Additionally, new skills required for medical practice, such as teamwork and innovation as a tool to solve health problems, challenged in recent years the classic paradigm of medical education. Therefore, the medical schools have developed multiple strategies to deal with it, such as curricular integration using competency-based education models, incorporating basic and clinical sciences in parallel during the curriculum, ensuring a relevant and applicable scientific knowledge throughout the training process. Although in Chile the Flexner prototype is still followed, the basic sciences are taught as single or integrated courses or using a systems approach. In this article we report a diagnosis about the local integration of fundamental sciences in medical training. We also compare our schools with those of Canada, Europe and Latin America. Recommendations aimed at modernizing medical school curricula are made.


Assuntos
Educação Médica , Faculdades de Medicina , Ciência , Chile , Currículo , Educação Médica/organização & administração , Humanos , Ciência/educação
11.
Otol Neurotol ; 39(10): e1069-e1077, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30212429

RESUMO

OBJECTIVE: To determine whether a reference electrode placed over the contralateral medical canthus is electrically indifferent to the ocular vestibular evoked myogenic potential (oVEMP). STUDY DESIGN: Prospective observational study. SETTING: Tertiary academic center. PARTICIPANTS: Nineteen otologically normal subjects. METHODS: oVEMPs were recorded using a 500 Hz tone burst at 125 dB pSPL using both a conventional dual infra-orbital derivation and contralateral infraorbital electrode referenced to a medial canthus electrode known as the "belly-tendon" derivation. RESULTS: The belly-tendon derivation produced significantly larger oVEMP amplitudes. This appears to be due to a polarity inversion of the first negative peak that occurs when the reference electrode is placed over the medial canthus. Thus, the belly-tendon derivation was associated with reference contamination, but in this instance the reference contamination produced an augmented oVEMP amplitude. CONCLUSIONS: Neither the dual infra-orbital nor belly-tendon electrode montages are electrically neutral. Reference contamination is the source of both a decrease in amplitude using conventional recording techniques and increased amplitude using the belly-tendon montage. The results support the contention that the belly-tendon montage generates a reversed polarity response, i.e., algebraically subtracted (i.e., added in the differential amplifier) from the response recorded at the infraorbital midline enhancing the oVEMP amplitude. It should be noted that the amplitude gained when using the belly-tendon montage may also be due to electromyographic (EMG) generated by extraocular muscles other than the inferior oblique generator, resulting in a loss of specificity. The authors recommend the belly-tendon montage be used in clinical situations where the oVEMP is absent or low in amplitude.


Assuntos
Estimulação Acústica/métodos , Eletrofisiologia/métodos , Potenciais Evocados Miogênicos Vestibulares/fisiologia , Adulto , Eletrodos , Feminino , Humanos , Masculino , Estudos Prospectivos
12.
Phys Rev Lett ; 121(4): 042501, 2018 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-30095940

RESUMO

Full calculations of six-nucleon reactions with a three-body final state have been elusive and a long-standing issue. We present neutron spectra from the T(t,2n)α (TT) reaction measured in inertial confinement fusion experiments at the OMEGA laser facility at ion temperatures from 4 to 18 keV, corresponding to center-of-mass energies (E_{c.m.}) from 16 to 50 keV. A clear difference in the shape of the TT-neutron spectrum is observed between the two E_{c.m.}, with the ^{5}He ground state resonant peak at 8.6 MeV being significantly stronger at the higher than at the lower energy. The data provide the first conclusive evidence of a variant TT-neutron spectrum in this E_{c.m.} range. In contrast to earlier available data, this indicates a reaction mechanism that must involve resonances and/or higher angular momenta than L=0. This finding provides an important experimental constraint on theoretical efforts that explore this and complementary six-nucleon systems, such as the solar ^{3}He(^{3}He,2p)α reaction.

13.
Obes Surg ; 28(10): 3259-3267, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29961179

RESUMO

AIM: Laparoscopic gastric plication (LGP) is a bariatric surgical technique based on the anatomical principles of laparoscopic sleeve gastrectomy (LSG), but its effects on the metabolic profile are still uncertain. The aim of our study is to compare the changes in weight, metabolic parameters and gastric histology following intervention by gastric plication (GP) and sleeve gastrectomy (SG) in an experimental model of obesity. METHODS: To conduct the study, 32 8-week-old male Sprague-Dawley rats (Charles River®) were fattened by means of a cafeteria diet and randomly assigned to the following experimental groups: group 1: GP (n = 12); group 2: SG (n = 12) and group 3: sham (n = 8). RESULTS: Unlike the SG group, the GP group attained the weight of the sham group at the end of the experiment (week 16). The GP group continued to eat more cafeteria diet than the SG group. In addition, the SG group achieved better glycaemic control than the GP group. Significantly higher plasma ghrelin levels were observed at week 16 in the GP group than in the SG group (2.29 ± 0.5 vs 1.07 ± 0.4, p < 0.05), which also occurred for the glucagon plasmatic levels (62.71 ± 36.2 vs 24.63 ± 9.3, p < 0.05). CONCLUSIONS: GP is not as effective as SG and cannot be considered a metabolic surgery due to observed hormonal variations. The animals subjected to a GP continued to have a high appetite for the cafeteria diet unlike the animals submitted to an SG. Hormonal mechanisms possibly related to glucagon and ghrelin may be involved in this metabolic response.


Assuntos
Ingestão de Energia/fisiologia , Gastrectomia/métodos , Obesidade/metabolismo , Obesidade/cirurgia , Estômago/cirurgia , Redução de Peso/fisiologia , Animais , Glicemia/metabolismo , Dieta Hiperlipídica , Modelos Animais de Doenças , Grelina/sangue , Glucagon/sangue , Laparoscopia/métodos , Masculino , Obesidade/etiologia , Obesidade/patologia , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley
14.
Phys Rev Lett ; 119(22): 222701, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29286782

RESUMO

Few-body nuclear physics often relies upon phenomenological models, with new efforts at the ab initio theory reported recently; both need high-quality benchmark data, particularly at low center-of-mass energies. We use high-energy-density plasmas to measure the proton spectra from ^{3}He+T and ^{3}He+^{3}He fusion. The data disagree with R-matrix predictions constrained by neutron spectra from T+T fusion. We present a new analysis of the ^{3}He+^{3}He proton spectrum; these benchmarked spectral shapes should be used for interpreting low-resolution data, such as solar fusion cross-section measurements.

15.
Obes Surg ; 27(11): 2836-2844, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28478583

RESUMO

INTRODUCTION: Laparoscopic sleeve gastrectomy is one of the most common techniques in bariatric surgery, but there is no consensus on the optimal distance from the pylorus to start the gastric transection. The aim of this study is to determine the differences in gastric emptying, gastric distension and metabolic response between two starting distances. MATERIAL AND METHODS: This is a prospective randomised study of 60 patients (30 patients with the section at 3 cm and 30 patients at 8 cm from the pylorus). We calculate at 6 and 12 months from surgery gastric emptying by scintigraphy (T1/2 min), gastric volume by CT scan (cc) and metabolic response by blood sample analysis (glucose, HbA1c, insulin, HOMA-IR, GLP-1, GIP and C-peptide). RESULTS: Gastric emptying increases the speed significantly in both groups but is greater in the 3-cm group (p < 0.05). Dividing groups into type 2 diabetic patients and non-diabetic patients, the speed in non-diabetic patients is significantly higher for the 3-cm group. Residual volume increases significantly in both groups, and there are no differences between them. One year after surgery, there are significant improvements in the hyperinsulinaemia in the patients of the 3-cm group with respect to the 8-cm group, but only in diabetic patients. No differences between groups are found regarding changes in GLP-1 or GIP. CONCLUSIONS: Gastric emptying is faster in patients with antrum resection. The distance does not influence the gastric emptying of diabetic patients. Other mechanisms may explain metabolic response besides GLP-1 and its association with improvements in diabetes via gastric emptying.


Assuntos
Gastrectomia/reabilitação , Esvaziamento Gástrico/fisiologia , Laparoscopia/reabilitação , Obesidade Mórbida/reabilitação , Obesidade Mórbida/cirurgia , Adulto , Idoso , Peptídeo C/sangue , Feminino , Gastrectomia/efeitos adversos , Gastrectomia/métodos , Peptídeo 1 Semelhante ao Glucagon/sangue , Glucose/metabolismo , Humanos , Insulina/metabolismo , Laparoscopia/efeitos adversos , Laparoscopia/métodos , Masculino , Pessoa de Meia-Idade , Obesidade Mórbida/metabolismo , Obesidade Mórbida/fisiopatologia , Tamanho do Órgão , Estudos Prospectivos , Piloro/fisiologia , Piloro/cirurgia , Estômago/diagnóstico por imagem , Estômago/patologia
16.
Inorg Chem ; 56(5): 2712-2721, 2017 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-28186742

RESUMO

The substitution of lithium for copper in Cu2ZnSnS4 (CZTS) has been experimentally and theoretically investigated. Formally, the (Cu1-xLix)ZnSnS4 system exhibits two well-defined solid solutions. Indeed, single crystal structural analyses demonstrate that the low (x < 0.4) and high (x > 0.6) lithium-content compounds adopt the kesterite structure and the wurtz-kesterite structure, respectively. For x between 0.4 and 0.6, the two aforementioned structure types coexist. Moreover, 119Sn NMR analyses carried out on a (Cu0.7Li0.3)2ZnSnS4 sample clearly indicate that lithium replaces copper preferentially on two of the three available 2-fold crystallographic sites commonly occupied by Cu and Zn in disordered kesterite. Furthermore, the observed individual lines in the NMR spectrum suggest that the propensity of Cu and Zn atoms to be randomly distributed over the 2c and 2d crystallographic sites is lowered when lithium is partially substituted for copper. Additionally, the first-principles calculations provide insights into the arrangement of Li atoms as a function of the Cu/Zn disorder and its effect on the structural (lattice parameters) and optical properties of CZTS (band gap evolution). Those calculations agree with the experimental observations and account for the evolutions of the unit cell parameters as well as for the increase of band gap when the Li-content increases. The calculation of the formation enthalpy of point defect unambiguously indicates that Li modifies the Cu/Zn disorder in a manner similar to the change of Cu/Zn disorder induced by Ag alloying. Overall, it was found that Li alloying is a versatile way of tuning the optoelectronic properties of CZTS making it a good candidate as wide band gap materials for the top cells of tandem solar cells.

17.
Artigo em Inglês | MEDLINE | ID: mdl-29423339

RESUMO

Addressing language and cultural nuance is required to improve the quality of care among all patients. The tenth version of the National Standards for Culturally and Linguistically Appropriate Services in Health Care (CLAS) recommends implementing ongoing assessments to integrate specific actions into measurement and continuous quality improvement activities. To this end, we have created the Interventional Cultural and Language Assistance Program (ICLAP). As part of ICLAP, we conducted a cross-sectional needs assessment survey with 564 consecutive patients receiving outpatient Positron emission tomography-computed tomography (PET/CT) imaging at a comprehensive cancer center in the five most prevalent languages of New York City: English, Spanish, Russian, Chinese, and Arabic. The purpose of this study is to describe the language assistance characteristics and needs of a sample of patients receiving care in the cancer center. We examined the relationship between race, ethnicity, birthplace, communication and language assistance characteristics and the satisfaction with the care received. Our results show that race and ethnicity, birthplace, cultural beliefs, language assistance, and communication characteristics were all factors associated with patients' satisfaction with care, illustrating that there is an unmet need among cancer patients to have cultural and linguistic sensitive services.

18.
Phys Rev Lett ; 117(3): 035002, 2016 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-27472118

RESUMO

Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of ^{6}Li in low-metallicity stars. Using high-energy-density plasmas we measure the T(^{3}He,γ)^{6}Li reaction rate, a candidate for anomalously high ^{6}Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.

19.
Phys Rev E ; 93(5): 052118, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27300841

RESUMO

We address characterization of many-body superradiant systems and establish a fundamental connection between quantum criticality and the possibility of locally estimating the coupling constant, i.e., extracting its value by probing only a portion of the whole system. In particular, we consider Dicke-like superradiant systems made of an ensemble of two-level atoms interacting with a single-mode radiation field at zero effective temperature, and address estimation of the coupling by measurements performed only on radiation. At first, we obtain analytically the quantum Fisher information (QFI) and show that optimal estimation of the coupling may be achieved by tuning the frequency of the radiation field to drive the system toward criticality. The scaling behavior of the QFI at the critical point is obtained explicitly upon exploiting the symplectic formalism for Gaussian states. We then analyze the performances of feasible detection schemes performed only on the radiation subsystem, namely homodyne detection and photon counting, and show that the corresponding Fisher informations (FIs) approach the global QFI in the critical region. We thus conclude that criticality is a twofold resource. On the one hand, global QFI diverges at the critical point, i.e., the coupling may be estimated with the arbitrary precision. On the other hand, the FIs of feasible local measurements (which are generally smaller than the QFI out of the critical region), show the same scaling of the global QFI; i.e., optimal estimation of coupling may be achieved by locally probing the system, despite its strongly interacting nature.

20.
Gen Comp Endocrinol ; 226: 50-5, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26723188

RESUMO

An understanding of stress physiology is important for species management because high levels of stress can hamper reproduction and affect an individual's ability to cope with threats to their survival, such as disease and human-wildlife conflict. A commonly used indicator of stress, faecal concentrations of cortisol metabolites (FCM), can be used to assess the impact of social, biological and environmental factors. Measurements of FCM are particularly valuable for endangered species that are logistically challenging to study and where non-invasive techniques are preferred. As the second most endangered canid in Africa, the African wild dog (Lycaon pictus) has been the focus of considerable conservation research, yet there is still little understanding of factors associated with stress, in either captive or free-ranging populations. The present study therefore aimed to determine whether stress levels differ between captive and free-ranging populations, and to detect social, biological and environmental factors that are stressful in these populations. Faecal samples were collected from 20 captive and 62 free-ranging animals. Within free-ranging populations, the sexes differed significantly, but there was no effect of social status, age or breeding period for either sex. Captive females had higher FCM concentrations than free-ranging females. In captive populations, FCM concentrations differed among zoos and with reproductive status in females, but were not related to age class or group-housing structure. In conclusion, FCM is a useful indicator of stress and should be considered an integrative aspect of management, for both in situ and ex situ African wild dog populations.


Assuntos
Canidae/fisiologia , Fezes/química , Glucocorticoides/análise , Reprodução/fisiologia , Estresse Fisiológico/fisiologia , Animais , Animais Selvagens/metabolismo , Cruzamento , Espécies em Perigo de Extinção , Feminino , Hidrocortisona/metabolismo , Masculino
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